CA2087980A1 - Device for information transmission - Google Patents
Device for information transmissionInfo
- Publication number
- CA2087980A1 CA2087980A1 CA002087980A CA2087980A CA2087980A1 CA 2087980 A1 CA2087980 A1 CA 2087980A1 CA 002087980 A CA002087980 A CA 002087980A CA 2087980 A CA2087980 A CA 2087980A CA 2087980 A1 CA2087980 A1 CA 2087980A1
- Authority
- CA
- Canada
- Prior art keywords
- antenna
- ground plane
- transponder
- microwave signal
- antenna layer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q1/00—Details of, or arrangements associated with, antennas
- H01Q1/12—Supports; Mounting means
- H01Q1/22—Supports; Mounting means by structural association with other equipment or articles
- H01Q1/2208—Supports; Mounting means by structural association with other equipment or articles associated with components used in interrogation type services, i.e. in systems for information exchange between an interrogator/reader and a tag/transponder, e.g. in Radio Frequency Identification [RFID] systems
- H01Q1/2225—Supports; Mounting means by structural association with other equipment or articles associated with components used in interrogation type services, i.e. in systems for information exchange between an interrogator/reader and a tag/transponder, e.g. in Radio Frequency Identification [RFID] systems used in active tags, i.e. provided with its own power source or in passive tags, i.e. deriving power from RF signal
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/74—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems
- G01S13/76—Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems wherein pulse-type signals are transmitted
- G01S13/767—Responders; Transponders
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
- G06K19/00—Record carriers for use with machines and with at least a part designed to carry digital markings
- G06K19/06—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code
- G06K19/067—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components
- G06K19/07—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips
- G06K19/077—Constructional details, e.g. mounting of circuits in the carrier
- G06K19/07749—Constructional details, e.g. mounting of circuits in the carrier the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
- G06K19/00—Record carriers for use with machines and with at least a part designed to carry digital markings
- G06K19/06—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code
- G06K19/067—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components
- G06K19/07—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips
- G06K19/077—Constructional details, e.g. mounting of circuits in the carrier
- G06K19/07749—Constructional details, e.g. mounting of circuits in the carrier the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card
- G06K19/07758—Constructional details, e.g. mounting of circuits in the carrier the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card arrangements for adhering the record carrier to further objects or living beings, functioning as an identification tag
- G06K19/07762—Constructional details, e.g. mounting of circuits in the carrier the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card arrangements for adhering the record carrier to further objects or living beings, functioning as an identification tag the adhering arrangement making the record carrier wearable, e.g. having the form of a ring, watch, glove or bracelet
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
- G06K19/00—Record carriers for use with machines and with at least a part designed to carry digital markings
- G06K19/06—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code
- G06K19/067—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components
- G06K19/07—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips
- G06K19/077—Constructional details, e.g. mounting of circuits in the carrier
- G06K19/07749—Constructional details, e.g. mounting of circuits in the carrier the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card
- G06K19/07773—Antenna details
- G06K19/07786—Antenna details the antenna being of the HF type, such as a dipole
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q9/00—Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements
- H01Q9/04—Resonant antennas
- H01Q9/0407—Substantially flat resonant element parallel to ground plane, e.g. patch antenna
Abstract
ABSTRACT OF THE DISCLOSURE
A device for information transmission, a so-called transponder, for receiving a first microwave signal, modulating and coding, and retransmitting a second microwave signal, comprising at least one antenna means made in microstrip technique is described. The device is characterized primarily in that the antenna means comprises an antenna layer, acting towards a ground plane, the antenna layer and the ground plane having essentially equal area, and in that the device further comprises a reflex means, arranged next to or at a distance of at most 1/6 of the air wave length of the first microwave signal from the edges of the antenna layer and the ground plane, so that an antenna lobe directional from the antenna means is obtained, comprised of directly transmitted microwave signal and reflected microwave signal. With this embodiment a device is obtained that is compact, effective, light and inexpensive and gives a well defined and directional antenna lobe for communication with a good range.
A device for information transmission, a so-called transponder, for receiving a first microwave signal, modulating and coding, and retransmitting a second microwave signal, comprising at least one antenna means made in microstrip technique is described. The device is characterized primarily in that the antenna means comprises an antenna layer, acting towards a ground plane, the antenna layer and the ground plane having essentially equal area, and in that the device further comprises a reflex means, arranged next to or at a distance of at most 1/6 of the air wave length of the first microwave signal from the edges of the antenna layer and the ground plane, so that an antenna lobe directional from the antenna means is obtained, comprised of directly transmitted microwave signal and reflected microwave signal. With this embodiment a device is obtained that is compact, effective, light and inexpensive and gives a well defined and directional antenna lobe for communication with a good range.
Description
2 0 8 7 ~ 8 ~ /SE91/~79 W~ 1~3 ~EVI~E FQ~ INFQRM~TIQN T~ L~SIO~
The present invention relates to a device for information transmission, a so-called transponder, :Eor receiving a first microwave signal, for modulation and coding, and for re-transmitting a second microwave signal, comprising at least one antenna means made in microstrip technique.
BACKGROUND OF THE INVENTION
Using microwave technique for information transmission to and from transponders has been known for a long time and is described in inter alia V.S. patents 4,242,661 "DeYice ~or registration of objects" and 4,390,880 "Radio communication lS system and transmitter and receiver equipment therefor".
It is further known from U.S. pa~ent 4,673,936 to integrate a microwave uni~ with a wrist watch, but that invention is intended as an emergency transmitter and comprises an active frequency sweeping microwave oscillator built into the watch and intended to be detected by a reconnaissance radar on-board a ship, thereby differing from the present invention in which no microwave oscillator in included, but in which information from the transponder is fetched through passive modulation and reflection of an illuminating microwave sig-nal. In addition, the mentioned device uses an entirely dif-ferent an~enna technique than the one presented here.
In many applications simultaneous demands are placed on good range, directionality and compact dimensions in the transponder, while, at the same time, the transmission fre-quency, which determines the size of the antenna, is prede-termined for technical reasons or due to authority regula-tions.
W~/01~3 2 D ~ 7 ~ ~ ~ P~T/S~91/~79 It is gener~l for all antennae that their dimension in otherwise static conditions are in inverse proportion ~o their operational frequency. Thus, an an~enna a~ e.g. 5 GHz has half the extension of a 2.5 GHz antenna.
Furthermore, the capability of the antemla to receive ~icro-wave radiation is directly proportional 1o its effective antenna area, and since a lower freguency antanna due to its larger physical dimensions has a larger antenna area ~square meter~, it is capable of detecting moxe power (Watt) if it is in a microwave field of a certain power densi~y (Watt per square meter) than would a higher frequency antenna with the same direction characte.ristics.
A high-frequency antenna can per se be given an increased effective antenna area by groupin~ several smaller antenna means side by side, but then there is the disadvantage of greater complexity and in that its directionality increases unfavourably, because the transponder must be directed care-fully at the write/read unit in order to obtain a goodrange A transponder with a large effec~ive antenna area and few antenna means in proportion to its total physical area therefore gives great advantages in applications with simul taneously high demands on compactness, range and freedom of orientation at a given radiation level.
Usual transponder frequencies are 2.45 GHz and 5.72 GHz, as there are internationally provided frequency bands which are commonly used for identification systems. Also 24 GHz has been provided internationally but has not yet come into any practical use, foremost due to high costs and low range per-formance.
W~2/0~3 2 ~ $ ~ ~ 8 ~ PCT/SE91~0~79 2.45 GH~ is also used by microwave ovens and through their-widely spread usage, among other things, it is anticipated that this frequency will remain publicly available in the foreseeable ~uture.
S' The mentioned frequencies are ~ufficiently low to enable the use of inexpensive silicon semiconductors and microstrip solutions in the microwave circuits, at the same time as the requirements for mechanic precision in impedance determining microstrip elements are moderate. The frequency is, however, sufficiently high for printed microstrip antennae to be used, which makes thin and easily manu~actured antenna designs possible.
lS A well designed transponder with microstrip antenna has usually a radiation diagram that has its principal direction in the normal plane of the antenna layer, outwards from the antenns layer, while its sensitivity in the opposite direc-tion is considerably depressed provided that ~he transponder antenna has a ground plane whose extension is considerably larger than that of the antenna layer. In practical cases, e.g. in so-called patch antennae for identification tags, the extension of the ground plane is usually chosen to approximately double the side of the antenna layer in order not to cause problems with undesirable back lobe effects.
A problem will then be that the microstrip antennae in transponder applications with directionality demands require large mounting space, whereby the applications are limited to such cases where there is space for this ground plane.
Often other transponder components as well, such as e.g.
power supplying means, microwave circuits, diodes, inte-grated circuits and passive components, require a consider-able mounting area. If the ground plane could be diminished the demands would be accentuated on alternative and more W~ ~2~1~3 ~ PCT/SE~ 79 space saving modes of construction for the mentioned com-ponents.
A ground plane diameter smaller than about twice the diame-ter of the antenna layer dis~urbs the antenna diagram so that its back lobe increases gradually with decreasing ground plane. If, therefore, the side of the antenna layer has been chosen to about 2 cm, which is typical at 2.45 GHz fre~Jency, and ceramic subs~rate wi~h a relative die-lectricity constant of about 10, the ground plane of theantenna should have at least 4 cm diameter in order to ob-tain a controlled directionality without back lobe.
When there is a backward lobe formed by a limited ground plane, a signal between the communication unit and the transponder antenna can also go via reflexes in objects located behind or diagonally beh1nd the antenna layer, which causes interference between direct and reflected signal with the risk of signal drop out in positions where reflected and direct signals vectorially cancel each other.
A problem has been that with known technique it has not been possible to integrate an inexpensive microwave transponder in compact applications, e.g. into wrist watches, within usual dimensions and weight, but one has been confined to systems operating with inductive technique where a coil in the watch is used as an antenna and where the range becomes extremely limited. With inductive technique it is neither possible to achieve the directionality that is possible with microwave technique, and it is difficult to achieve a high data transmission speed.
A microwave based product would otherwise be capable of solving many problems with electronic passage control, elec-tronic payment etc. Applied to wrist watches the technique w~ g~3 ~ ~ ~ PCTtSE91/~79 would provide for directionality, good range, high datatransmission speed and power saving, whereby very available and safe systems could be built. Applied to 5.7 G~1z frequen-cy range and a ceramic substrate the diameter of the trans-S ponder will only be about one cen~imetre, which can be in-cluded wi~hout dif~iculty in a small ladies' wa~ch.
In addition, as the cost for a microwave based write~read unit is low, the applications could embrace most of the applications that are curren~ly covered by magnetic cards, memory cards, microprocessor cards, various key systems and various ticket systems. In an embodiment with particularly high sensitivity to a received microwave signal the device could furthermore ~e used as a pager.
The most compact microwave based transponder systems that currently exist are transponders in credit card format, but these are usually carried in a wal}et or pocke~ and thereby require to be taken out before access can occur. Further-more, the risk of theft is obvious, as is the problem ofleaving the transponder.
For applications in material flow automation and traffic in-formation applications antennae have been used hitherto with a more co~ventional design, with the antenna layer facing ~he direction of radiation and with a quite large ground plane. Although this has admitted great freedom in instal-ling the transponders on an optional mounting area, e.g. in a car window, on a plastic palette etc. without any problem of multiple-way extension from appearing back lobe radia-tion, there are nevertheless many applications where it is always known that the transponder is going to be mounted on a metal plane, while on the same time there is a need for the transponder to be small. Some examples are given of W~ g~3 ~ a g ~ PCr~E91~79 identifying gas bottles and beer-cans, which must be identi-fied on refilling and distribution.
On these products there is extremely little space available for the identity tags/escort memories, and in addi~ion they have to be protected from the very rough treatment and che-mical effects that occur when t~e products are handled, when at the same time there are quite high demands on range and s~fe identification also in dirty environments. A small transponder according to the invention would here make pos-sible an automatic information handling around the material flow.
Another example is given on automatic reading of the mileage of a rental car. Today, this must be effected manually, while with a product according to the invention, integrated ~ith an electronic mileage counte~ in the car wheel hub, with microwave technique it would be possible to perform the reading automatically. The space available at the wheel hub is very much limi~ed, but could include a transponder for automatic remote reading according to the invention.
Although choosing higher microwave frequencies would make smaller dimensions in the transponder antenna po5siblet other limitations would come instead, such as size and cost of other components, difficulties with international fre-quency permissions and increased sensitivity to environ-mental factors such as waterfilm and dirt on the trans-ponder.
THE OBJECT AND MOST IMPORTA~T CH~RACTERISTICS OF THE
INVENTION
The object of the present invention is to provide a device for information transmission, a so-called transponder, o' W~ Q~lgS3 ~ ~ ~ 7 ~ ~ ~ PCr/SE91/~0419 the kind mentioned in the introduction, that is compact, effective, light and inexpensive, and that gives a well-defined and directional antenna lobe for communication with a good range.
s According to the invention such a device is characterized primarily in that the antenna means comp.rises an antenna layer, acting towards a ground plane, the antenna layer and the ground plane having principally equal area, and that the device further `comprises a reflex means, arranged next to, or at a distance of at most 1~6 of the air wave length of the first microwave signal from, the radiating edges of the antenna layer, arranged to reflect the second microwave sig-- nal that goes out from the radiating edges of the antenna layer and the ground plane edges, so that an antenna lobe, directional from the antenna means, comprised of a directly transmitted microwave signal and a reflected microwave signal is obtained.
If the device is designed with the antenna layer and ground plane having equal area, equally large antenna lobes are ob-tained in the normal direction of ~he antenna layer, in both the forward and rearward directions. ~y arranging a reflex means in the described manner a directional antenna lobe is only obtained in the forward direction.
As already mentioned, there is a lower limit for the size of the ground plane in relation to the size of the antenna layer, because the back lobe increases with decreasing ground plane. As the object of the invention is to achieve a compact device, i.e. a transponder of the kind mentioned in the introduction, in practice, there is a certain limit up-wards for the size of the ground plane in relation to the size of the antenna layer. Accordin~ to this invention the relation lies between a first radius of a circle, circum-w~ ~Jolgs3 ~ ~ ~ 7 ~ ~ ~ PCr/SE9lJ~79 scribing the antenna layer, and a second radius, circumscri-bing the ground plane in the interval 0.6 to 1.7.
In a preferred embodiment of the invention the transponder components with relatively large extension, such as power source and/or microstrip conductor, are positioned entirely or partly within the innermost of the cylinder walls that can be conceived to circumscribe the antenna layer or ground plane. Xereby ~urther objectives to provide a compact device of the kind ~entioned in the introduction are met The de-sign of the antenna means acts in the same direction, in the form of a patch antenna, which via a substrate of dielectric material interacts with a ground plane. The antenna means can also be formed as a single folded or doubel folded dipole antenna in microstrip technique, which via a sub-strate of dielectric material interac~s with a ground plane.
For space-saving purposes the microstrip conductors of the device can be loc~ted entirely or partly in openings withln their antenna layer in order there to interact through the same substrate with the same gxound plane as the antenna layer, in which arrangement there are no electric throuyh-connections through the substrate.
The described embodiments entail that the weight can be kept low, because the described antenna means only requires a limited dielectric substrate, typically, only one fourth of the weight of a corresponding substrate in a conventional transponder. In addition, this advantage i9 gained tha-t the microwave signal frequency can be kept relatively }ow, in the order of 2-6 GHz, which gives a relatively large antenna area compared with that which would have been available with a higher frequency with the same antenna diagram of the de-vice.
Wf `~/019~3 ~ PCT/SEl31/~79 Because the substrate is relatively expensive the use of a limited substrate is cost-saving. Since the device is of limited size a substrate with relatively low dielectricity constant can come into use, which otherwise would have en-tailed larger dimensions in a conventional transponder. Theconnection technique for the used electronic components is also simple in the device according to the invention.
The device according to the invention finds applications in many areas where a compact txansponder is re~uired. As to personally carried transponders the device can in an embodi-ment be arranged as a compac~ box, intended to be carxied by a person in direct or close body contact. Thereby, the men-tioned reflex means can be constituted by the bottom of the lS box, and~or be constituted by the persons's body surface. A
particularly advantageous embodiment of the device according to the invention with this design consists in that the transponder has been integrated with a watch to be carried at a person's wrist, i.e. a wrist watch, whereby the men-tioned reflex means can be constituted by the clock caseandtor the person's ~rist surface.
The integration with a watch creates many constructive pos-sibilities within the scope of the invention. The ground plane can, for example, be formed integrated with the visi-ble clock face, whereas the antenna layer and other compo-nents, such as clockwork, power source, electronic cornpo-nents and microstrip conductors are located between the clock face and the clock case.
In a suitable embodiment of the invention a chip is used in common for controlling the clockwork of the watch or other time indicator located in the watch and storing a code which is unique for the watch, the chip contributing to the infor mation transmission to and from the transponder. The trans-W~ 19~3 2 ~ PCT/S~91/~79 ponder can be arranged to store or transmit, directly or in-directly, time functions inbuilt in the watch.
lf the transponder is included in a system or pay control S or the like, it can be suitable that an i.ndicator means ar-ranged on the device shows the result of transactions via the first and/or second microwave signal, such as balance and sta~us information.
To increase safety against unauthorized use of the device according to the invention it can be arranged to admit cer-tain transac~ions only during a predetermined time interval, initiated in a manner such that at least one operational means in the device has been acted upon, possibly in a lS manner which is specific for each watch.
Again with the object to increase safety in the use of the device it can be arranged to admit certain data transactions via the first and/or second microwave signal partly coded, for example according to DES or RSA, provided that the transponder is progra~med with a corresponding algorithm.
In a practical embodiment of a personally carried device according to the invention, on receiving a first microwave signal, transmitting a code which is preprogrammed in the transponderr the device is arranged to give an acoustic sig-nal and possible also visual information on an indicator means.
As to application on vehicles or for goods or goods carrier in the flow of materials the mentioned reflex means can of-ten be a surface, particularly metallic surface, on which the device according to the invention is attached.
WO-~/019~3 PCT/SE91/0~79 A possible application is to be found in the area of reading mileage in vehicles of a vehicle fleet. Hitherto this had to be done manually, whereas with a product according to the inven~ion, applied to the vehicle wheel hub, combined with an electronic mileage counter in the vehicle wheel hub, automatic remote reading could be arranged.
DESCRIPTION OF THE DRAWINGS
The invention will now be described in more detail with re-ference to the accompanying figures, of which Figure 1 shows a block diagram of a known device, i.e. a transponder;
Figure 2 shows a conventional microstrip antenna in perspec-tive;
Figure 3 shows a view of a device according to the inven-tion;
.
Figure 4 shows a cross section of a device, integrated with a watch;
Figure 5 shows, in perspective, the device according to Figure 4 in the form of a wrist watch on a wrist;
Figure 6 and 7 show views of alternative embodiments of the antenna means according to the invention.
DESCRIPTION OF EMBODIMENTS OF THE INVENTION
Figure 1 shows a block diagram of a known transponder for information transmission, for example an identification tag, .
Wr~2/nl~3 2 ~ ~ 7 ~ PCT/SE91/~0479 and i~ based on the principle ~hat an incoming microwave signal is modified and reflected The antenna 1 receives a microwave frequency, fox example at 2.45 GHz, from en transmission/receiving unit and passes this signal onward to modulation circuits in the modulator-demodulator unit 2. Depending on ~he memory contents in the oscillator memory circuit 3 the modulator supplies informa-tion to the signal received by ~he transponder, and retrans-mits the modulated signal to the antenna 1, so that the in-formation is radiated out into space in front of the trans-ponder to the transmission/receiving unit so that it can read information rom the transponder.
In the case where data is to be written in the transponder a modulated microwave signal is transmitted to the antenna 1, demodulated in the circuit ~ and stored in a memory in the oscillator memory circuit 3.
The modulator circuits are controlled from the oscillator with a signal with low frequency compared with the microwave signal, for example at 32768 Hz. An output signal 4 from the oscillator can also suitably be used for the time signalling of the watch. A power source in the unit 5 supplies the oscillator-memory circuit 3 with voltage, and can also com-prise a clockwork if the invention is integrated with a watch.
Figure 2 shows a known conventional microstrip antenna, where a ~ielectric substrate 10 on one side has an antenna layer 11 of metal while a ground plane 12 of metal is loca-ted on the opposite side of the antenna layer. A battery 13 for the power supply of the transponder is located on the ground plane side, blocked out in the figure.
wr ~/01~3 ~ ~ ~ 7 3 ~ ~ PCT/SE91/~79 If an electric alternating voltage relative to the ground plane 12 is applied in or nearby the area 14 of the antenna layer, a standing wave will build up in the half-a-wave-length antenna in such a manner that radia~ion goes out from the electric field at the ends of the antenna layer, indi~
cated by the arrows 15, so that a wave is transplanted in the normal direction 16 of the antenna. In the rev~rse situation the radiation coming in towards the antenna layer causes an alternating voltage in the area 14.
~owever, this is the case only if the ground plane 12 is considerably larger than the antenna layer 11, or else the antenna will also radiate in the opposite direction to the perpendicular 16.
Figure 3 shows a transponder construction where an antenna patch 20 and a ground plane 21 are about the same size, and where an opening 22 has been made in the antenna layer to pro~ide space for components and microwave circuits. This an~enna type, if located in free space, will radiate about as much in both the directions of the perpendiculars. If, however, the antenna, as in the invention, is positioned nearby a reflection plane 23, typically smaller than one tenth of the air wave length from the antenna layer, the wave that is radiated out in the direction towards the reflection plane will be reflected in it and give a wave that interacts with the earlier described radiation out from the antenna layer. The exact proximity to the reflection plane is comparatively uncritical, which is why a trans-ponder with a straight ground plane can be mounted withoutdifficulty on a curved reflection surface.
It is to be noted that the radiation comes from the edges of the antenna layer, and that no real.radiation is created directly from the central parts of the antenna layer sur-W~ ~01953 2 ~ S V PCT/SEg~ 79 face. Therefore, ~his surface can be used for other purpo-ses, for example to mount the circuits 25-~6 in the opening 22 within the an~enna layer 20f which circuits are required to achieve an electric modulation, by means of a modulator diode 24, with information in the feed point o~ the antenna layer 29 and to detect incoming signals with a detector diode 28.
It is also possible, without disturbing the antenna func-tion, to place larger components such as a power source and the mechanic parts of a watch inside the radiating edge sur-faces of the antenna layer. These details can for reasons of symmetry be located optionally on ~he same side as the com-ponents in ~igure 3 or on that side of the ground plane 21 which faces the reflection surface 23. The transponder pro-vides ~he intended function irrespective of which of the surfaces 20 or 21 is positioned towards the reflection plane and irrespective of wh~ch side the power source or the mechanical parts of the watch are located on.
A signal received by the antenna layer 20 will give an electric alternating current field over the dielectric 30 towards the ground plane 21 in the feed point 29 of the an-tenna, which is located in, or beside, an area corresponding to the area 14 of the antenna layer in figure 2.
The received signal is conducted by the microstrip conductor 31 to a diode 24, whose impedance can be varied between dif-ferent values depending on what voltage is put on its termi-nals. In the example of the embodiment there is an inte-grated circuit 2S, which on its output terminal 32 emits a control voltage to the diode 24 which acts on its impedance.
One side of the diode, from a microwave viewpoint, is short-circuited to the ground plane 21 by the open quarter-wave conductor 33, and thus, depending on the output voltage from '2/01~3 15 PCr/SE9l~ ~ 7 the circuit 25, microwave-wise it will more or less connect the point 29 to the ground plane 21. The component 26 is a resonance element for an oscillator in the circuit 25, and is also suitably used for an oscillator in the circuit 25, and is also suitably used for the time keeping of the watch.
The above-described impedance variation in the diode 24 will cause that a wave front falling in towards the antenna layer 20 gives rise to a reflex modulated with information, where-by instantaneous phase position and amplitude are affectedby the impedance in the diode 24. Because the circuit 25 is caused to hold data information ~hat is allowed to afEect the impedance of the diode 24, for example by varying the frequency or the phase in an alternating voltage on the output texminal 32 in a manner representative of data information, a tr~nsponder has been achieved whose data at radiation can be read with the aid of an ex~ernal communi-cation unit. The communication unit is caused to receive and decode the signal that is reflected ~rom the transponder and modulated with data.
The connections 39 and 35 feed voltage to the transponder circuits from a power source, which is not shown in figure 3. Connection 34 has, because of space, been located in a cut in the external edge of the antenna layer 20, but this is of no importance for the function of the antenna because the antenna has a minimum of current in this point.
From an output terminal 38 on the circuit 25 second pulses are fetched for controlling the clockwork of a watch.
The diode 28 can be used for the am~litude detection of a signal that falls into the transponder, which signal, if it represents a data current to the transponder~ makes it pos-sible to write data into the circuit 25. The data signal ~7~
W ~2/~1~3 PCT/S~lJ~79 reaches the circui~ 25 via the capacitor 27, while thedirect conductor between the circuit 25 and detector diode 28 is used to bias the diode.
One further use of the diode 28 is as a rectifier of micro-wave pulses to be used to supply power to the transponder instead of, or as a complement to, its inbuilt power source.
Furthermore, the antenna layer can be provided with an addi-tional feed point so that the transponder, in a known man-ner, can function simultaneously in two polarisations ortho-gonal to each other.
In the case where it is desired to have a s~ronger reflected lS signal than can be achieved with the hitherto described de-vice, it is also possible ~hat the device receives a signal in one polarisation and retransmits the reflex in the other polarisation aft~r modulation and amplification. ~ecause the polarisations for reception and amplified retransmitted sig-nal are separate, the risks of crosstalk and self-oscilla-tion axe avoided.
The antenna layer opening can also be formed assymmetrically in various manners in order, for example, to make the trans-ponder polarisation circular.
It is also possible to use one of the diodes for writing in data in the transponder and the other diode for reading via two orthogonally polarised channels, independent of each other. Alternati~ely, one of the diodes can be used for rectification of incoming power supplying signals in the microwave area.
The diodes can also be integrated with the circuit 25.
PCTJS~ 79 ~v2/0~9~3 2~7~
The modulation circuits can also be formed in other ways, for example, by complementing or replacing the diode 24 and the micros~rip conductor 33 by other components.
In order to avoid demands for the transponder to be oriented in any specific manner relative to the rotational axis from the transmitter/receiver, it can be designed for transmis-sion and reception of circularly polarised waves. The trans-ponder, if it is linearly polarised, will in this case still be capable of being turned about said axis without signal drop out, as a cixcularly polarised wave comprises E fields in all directions at right angles from the direction of radiation.
lS An alternative embodiment of the transponder is to let the feed point 29 of the antenna layer, via a through-connection conductor, stand in connection with circuits located on the other side and on their own carrier. This solution can be used when there is a need for more space than is available in the opening 22 without the antenna function being disturbed.
Figure 9 shows the invention integrated with a wrist watch with the antenna l~yer 20 turned inwards toward the wrist and where the transponder and its ground plane 21 constitute a unit integrated with the clock face. In a manner described earlier, what remains of the signal towards the watch case 42 and the wrist 43 will after reflection interact with the direct radiation out fro~ the transponder.
Battery 90, clockwork 41, electronic circuits and microwave circuits are mounted on the side of the antenna layer, in-side the external limiting line of the antenna layer.
W~2/~19~3 ~ ~ $ ~ PCT/S~I/M~79 Figure 5 shows a view of a wrist watch, where, for example, the ground plane and clock face constitute an integrated unit 50. An indicator 51 can, besides showing the time, give indications that are related to information transmission, memory contents, status and other information.
Integrated with functions of similar type that is used in transaction cards, for example according to ISO 7~16, trans-actions can be effected with a wrist mounted ~ransponder, and in addition the result can be displayed on an indicator 51 that is controlled from the electronic circui~s of the watch.
In simpler applications the transponder can be designed to store information according to the widely spread standards that apply to many credit cards and tickets with magnetic strips, and in many applications directly replace these in that the magnetic card reader is r~placed by a microwave based write/read unit for the transponder.
Unauthorized access to the transponder can be prevented in that its function is normally locked. Release can be effec-ted in that one or more operational means 52 on the wrist watch are acted upon, possibly in a manner which is specific for the watch.
In the case where a very hi.gh degree of security is requi-red, e.g. if the device is to store value related informa-tion, such as electronic punches or money, it can be provi-ded with means that provides sufficient safety againstunauthorised access. This can be effected in a similar manner as that used for pay cards of magnetic strip type, for electronic memory cards or for microprocessor cards. In the latter case a microprocessor with coding functions, for W~ '2/019~3 ~ r~ PCT/SE9l/~79 example the standardized DES and RSA algorithms, are implemented.
The antenna layer can also be given another embodiment, for example rectangular, without having its function principle altered. Furthermore, other antenna types than patch anten-nae can be chosen, e.g. with greater ban~ width but somewha~
less effective microstrip dipoles. The advantage with such a type of an~enna could be that it can be made to function at the same time at 2.45 and 5.7 GHz. -Figure 6 shows such an embodiment where the antenna layer isconstituted by a folded dipole on the ground plane in :micro-strip technique, which in its function partly resembles the patch antenna. The dipole element is constituted by the metal surface 60 which via a dielectric substrate 30 stands in connection with a ground plane 21, and where the unit is mounted on a reflected surface 23. The modulation of an in-coming microwave signal is effected with the aid of compo-nents which are connected to the antenna layer in the feedpoints 63 in a similar manner as has been described earlier.
Figure 7 shows a~ alternative embodiment of the transponder where an array 71 of two folded microstrip dipoles acts to-wards the ground plane 21. The microwave signal is connectedin the feed points 72 and the unit is mounted on a reflec-ting surface 23.
The device can also be provided with a mare sensitive recei-ver than with the diode detector 28 that has been shown in earlier examples of embodiments, and can be formed to act on an acoustic means integrated in a known way with the watch, being used for microwave based pager applications, whereby on receiving a special code via the.microwave link it emits w~ "~Jo19~3 2 Gl 8 ~ 9 8 ~ Pcr/sEgt/on479 ~o an observation signal to the carrier and possibly shows re-lated information on the indicator.
The invention is not limited to the examples of embodiments S as described here, and can be varied wi~hin the scope of the presented claims.
The present invention relates to a device for information transmission, a so-called transponder, :Eor receiving a first microwave signal, for modulation and coding, and for re-transmitting a second microwave signal, comprising at least one antenna means made in microstrip technique.
BACKGROUND OF THE INVENTION
Using microwave technique for information transmission to and from transponders has been known for a long time and is described in inter alia V.S. patents 4,242,661 "DeYice ~or registration of objects" and 4,390,880 "Radio communication lS system and transmitter and receiver equipment therefor".
It is further known from U.S. pa~ent 4,673,936 to integrate a microwave uni~ with a wrist watch, but that invention is intended as an emergency transmitter and comprises an active frequency sweeping microwave oscillator built into the watch and intended to be detected by a reconnaissance radar on-board a ship, thereby differing from the present invention in which no microwave oscillator in included, but in which information from the transponder is fetched through passive modulation and reflection of an illuminating microwave sig-nal. In addition, the mentioned device uses an entirely dif-ferent an~enna technique than the one presented here.
In many applications simultaneous demands are placed on good range, directionality and compact dimensions in the transponder, while, at the same time, the transmission fre-quency, which determines the size of the antenna, is prede-termined for technical reasons or due to authority regula-tions.
W~/01~3 2 D ~ 7 ~ ~ ~ P~T/S~91/~79 It is gener~l for all antennae that their dimension in otherwise static conditions are in inverse proportion ~o their operational frequency. Thus, an an~enna a~ e.g. 5 GHz has half the extension of a 2.5 GHz antenna.
Furthermore, the capability of the antemla to receive ~icro-wave radiation is directly proportional 1o its effective antenna area, and since a lower freguency antanna due to its larger physical dimensions has a larger antenna area ~square meter~, it is capable of detecting moxe power (Watt) if it is in a microwave field of a certain power densi~y (Watt per square meter) than would a higher frequency antenna with the same direction characte.ristics.
A high-frequency antenna can per se be given an increased effective antenna area by groupin~ several smaller antenna means side by side, but then there is the disadvantage of greater complexity and in that its directionality increases unfavourably, because the transponder must be directed care-fully at the write/read unit in order to obtain a goodrange A transponder with a large effec~ive antenna area and few antenna means in proportion to its total physical area therefore gives great advantages in applications with simul taneously high demands on compactness, range and freedom of orientation at a given radiation level.
Usual transponder frequencies are 2.45 GHz and 5.72 GHz, as there are internationally provided frequency bands which are commonly used for identification systems. Also 24 GHz has been provided internationally but has not yet come into any practical use, foremost due to high costs and low range per-formance.
W~2/0~3 2 ~ $ ~ ~ 8 ~ PCT/SE91~0~79 2.45 GH~ is also used by microwave ovens and through their-widely spread usage, among other things, it is anticipated that this frequency will remain publicly available in the foreseeable ~uture.
S' The mentioned frequencies are ~ufficiently low to enable the use of inexpensive silicon semiconductors and microstrip solutions in the microwave circuits, at the same time as the requirements for mechanic precision in impedance determining microstrip elements are moderate. The frequency is, however, sufficiently high for printed microstrip antennae to be used, which makes thin and easily manu~actured antenna designs possible.
lS A well designed transponder with microstrip antenna has usually a radiation diagram that has its principal direction in the normal plane of the antenna layer, outwards from the antenns layer, while its sensitivity in the opposite direc-tion is considerably depressed provided that ~he transponder antenna has a ground plane whose extension is considerably larger than that of the antenna layer. In practical cases, e.g. in so-called patch antennae for identification tags, the extension of the ground plane is usually chosen to approximately double the side of the antenna layer in order not to cause problems with undesirable back lobe effects.
A problem will then be that the microstrip antennae in transponder applications with directionality demands require large mounting space, whereby the applications are limited to such cases where there is space for this ground plane.
Often other transponder components as well, such as e.g.
power supplying means, microwave circuits, diodes, inte-grated circuits and passive components, require a consider-able mounting area. If the ground plane could be diminished the demands would be accentuated on alternative and more W~ ~2~1~3 ~ PCT/SE~ 79 space saving modes of construction for the mentioned com-ponents.
A ground plane diameter smaller than about twice the diame-ter of the antenna layer dis~urbs the antenna diagram so that its back lobe increases gradually with decreasing ground plane. If, therefore, the side of the antenna layer has been chosen to about 2 cm, which is typical at 2.45 GHz fre~Jency, and ceramic subs~rate wi~h a relative die-lectricity constant of about 10, the ground plane of theantenna should have at least 4 cm diameter in order to ob-tain a controlled directionality without back lobe.
When there is a backward lobe formed by a limited ground plane, a signal between the communication unit and the transponder antenna can also go via reflexes in objects located behind or diagonally beh1nd the antenna layer, which causes interference between direct and reflected signal with the risk of signal drop out in positions where reflected and direct signals vectorially cancel each other.
A problem has been that with known technique it has not been possible to integrate an inexpensive microwave transponder in compact applications, e.g. into wrist watches, within usual dimensions and weight, but one has been confined to systems operating with inductive technique where a coil in the watch is used as an antenna and where the range becomes extremely limited. With inductive technique it is neither possible to achieve the directionality that is possible with microwave technique, and it is difficult to achieve a high data transmission speed.
A microwave based product would otherwise be capable of solving many problems with electronic passage control, elec-tronic payment etc. Applied to wrist watches the technique w~ g~3 ~ ~ ~ PCTtSE91/~79 would provide for directionality, good range, high datatransmission speed and power saving, whereby very available and safe systems could be built. Applied to 5.7 G~1z frequen-cy range and a ceramic substrate the diameter of the trans-S ponder will only be about one cen~imetre, which can be in-cluded wi~hout dif~iculty in a small ladies' wa~ch.
In addition, as the cost for a microwave based write~read unit is low, the applications could embrace most of the applications that are curren~ly covered by magnetic cards, memory cards, microprocessor cards, various key systems and various ticket systems. In an embodiment with particularly high sensitivity to a received microwave signal the device could furthermore ~e used as a pager.
The most compact microwave based transponder systems that currently exist are transponders in credit card format, but these are usually carried in a wal}et or pocke~ and thereby require to be taken out before access can occur. Further-more, the risk of theft is obvious, as is the problem ofleaving the transponder.
For applications in material flow automation and traffic in-formation applications antennae have been used hitherto with a more co~ventional design, with the antenna layer facing ~he direction of radiation and with a quite large ground plane. Although this has admitted great freedom in instal-ling the transponders on an optional mounting area, e.g. in a car window, on a plastic palette etc. without any problem of multiple-way extension from appearing back lobe radia-tion, there are nevertheless many applications where it is always known that the transponder is going to be mounted on a metal plane, while on the same time there is a need for the transponder to be small. Some examples are given of W~ g~3 ~ a g ~ PCr~E91~79 identifying gas bottles and beer-cans, which must be identi-fied on refilling and distribution.
On these products there is extremely little space available for the identity tags/escort memories, and in addi~ion they have to be protected from the very rough treatment and che-mical effects that occur when t~e products are handled, when at the same time there are quite high demands on range and s~fe identification also in dirty environments. A small transponder according to the invention would here make pos-sible an automatic information handling around the material flow.
Another example is given on automatic reading of the mileage of a rental car. Today, this must be effected manually, while with a product according to the invention, integrated ~ith an electronic mileage counte~ in the car wheel hub, with microwave technique it would be possible to perform the reading automatically. The space available at the wheel hub is very much limi~ed, but could include a transponder for automatic remote reading according to the invention.
Although choosing higher microwave frequencies would make smaller dimensions in the transponder antenna po5siblet other limitations would come instead, such as size and cost of other components, difficulties with international fre-quency permissions and increased sensitivity to environ-mental factors such as waterfilm and dirt on the trans-ponder.
THE OBJECT AND MOST IMPORTA~T CH~RACTERISTICS OF THE
INVENTION
The object of the present invention is to provide a device for information transmission, a so-called transponder, o' W~ Q~lgS3 ~ ~ ~ 7 ~ ~ ~ PCr/SE91/~0419 the kind mentioned in the introduction, that is compact, effective, light and inexpensive, and that gives a well-defined and directional antenna lobe for communication with a good range.
s According to the invention such a device is characterized primarily in that the antenna means comp.rises an antenna layer, acting towards a ground plane, the antenna layer and the ground plane having principally equal area, and that the device further `comprises a reflex means, arranged next to, or at a distance of at most 1~6 of the air wave length of the first microwave signal from, the radiating edges of the antenna layer, arranged to reflect the second microwave sig-- nal that goes out from the radiating edges of the antenna layer and the ground plane edges, so that an antenna lobe, directional from the antenna means, comprised of a directly transmitted microwave signal and a reflected microwave signal is obtained.
If the device is designed with the antenna layer and ground plane having equal area, equally large antenna lobes are ob-tained in the normal direction of ~he antenna layer, in both the forward and rearward directions. ~y arranging a reflex means in the described manner a directional antenna lobe is only obtained in the forward direction.
As already mentioned, there is a lower limit for the size of the ground plane in relation to the size of the antenna layer, because the back lobe increases with decreasing ground plane. As the object of the invention is to achieve a compact device, i.e. a transponder of the kind mentioned in the introduction, in practice, there is a certain limit up-wards for the size of the ground plane in relation to the size of the antenna layer. Accordin~ to this invention the relation lies between a first radius of a circle, circum-w~ ~Jolgs3 ~ ~ ~ 7 ~ ~ ~ PCr/SE9lJ~79 scribing the antenna layer, and a second radius, circumscri-bing the ground plane in the interval 0.6 to 1.7.
In a preferred embodiment of the invention the transponder components with relatively large extension, such as power source and/or microstrip conductor, are positioned entirely or partly within the innermost of the cylinder walls that can be conceived to circumscribe the antenna layer or ground plane. Xereby ~urther objectives to provide a compact device of the kind ~entioned in the introduction are met The de-sign of the antenna means acts in the same direction, in the form of a patch antenna, which via a substrate of dielectric material interacts with a ground plane. The antenna means can also be formed as a single folded or doubel folded dipole antenna in microstrip technique, which via a sub-strate of dielectric material interac~s with a ground plane.
For space-saving purposes the microstrip conductors of the device can be loc~ted entirely or partly in openings withln their antenna layer in order there to interact through the same substrate with the same gxound plane as the antenna layer, in which arrangement there are no electric throuyh-connections through the substrate.
The described embodiments entail that the weight can be kept low, because the described antenna means only requires a limited dielectric substrate, typically, only one fourth of the weight of a corresponding substrate in a conventional transponder. In addition, this advantage i9 gained tha-t the microwave signal frequency can be kept relatively }ow, in the order of 2-6 GHz, which gives a relatively large antenna area compared with that which would have been available with a higher frequency with the same antenna diagram of the de-vice.
Wf `~/019~3 ~ PCT/SEl31/~79 Because the substrate is relatively expensive the use of a limited substrate is cost-saving. Since the device is of limited size a substrate with relatively low dielectricity constant can come into use, which otherwise would have en-tailed larger dimensions in a conventional transponder. Theconnection technique for the used electronic components is also simple in the device according to the invention.
The device according to the invention finds applications in many areas where a compact txansponder is re~uired. As to personally carried transponders the device can in an embodi-ment be arranged as a compac~ box, intended to be carxied by a person in direct or close body contact. Thereby, the men-tioned reflex means can be constituted by the bottom of the lS box, and~or be constituted by the persons's body surface. A
particularly advantageous embodiment of the device according to the invention with this design consists in that the transponder has been integrated with a watch to be carried at a person's wrist, i.e. a wrist watch, whereby the men-tioned reflex means can be constituted by the clock caseandtor the person's ~rist surface.
The integration with a watch creates many constructive pos-sibilities within the scope of the invention. The ground plane can, for example, be formed integrated with the visi-ble clock face, whereas the antenna layer and other compo-nents, such as clockwork, power source, electronic cornpo-nents and microstrip conductors are located between the clock face and the clock case.
In a suitable embodiment of the invention a chip is used in common for controlling the clockwork of the watch or other time indicator located in the watch and storing a code which is unique for the watch, the chip contributing to the infor mation transmission to and from the transponder. The trans-W~ 19~3 2 ~ PCT/S~91/~79 ponder can be arranged to store or transmit, directly or in-directly, time functions inbuilt in the watch.
lf the transponder is included in a system or pay control S or the like, it can be suitable that an i.ndicator means ar-ranged on the device shows the result of transactions via the first and/or second microwave signal, such as balance and sta~us information.
To increase safety against unauthorized use of the device according to the invention it can be arranged to admit cer-tain transac~ions only during a predetermined time interval, initiated in a manner such that at least one operational means in the device has been acted upon, possibly in a lS manner which is specific for each watch.
Again with the object to increase safety in the use of the device it can be arranged to admit certain data transactions via the first and/or second microwave signal partly coded, for example according to DES or RSA, provided that the transponder is progra~med with a corresponding algorithm.
In a practical embodiment of a personally carried device according to the invention, on receiving a first microwave signal, transmitting a code which is preprogrammed in the transponderr the device is arranged to give an acoustic sig-nal and possible also visual information on an indicator means.
As to application on vehicles or for goods or goods carrier in the flow of materials the mentioned reflex means can of-ten be a surface, particularly metallic surface, on which the device according to the invention is attached.
WO-~/019~3 PCT/SE91/0~79 A possible application is to be found in the area of reading mileage in vehicles of a vehicle fleet. Hitherto this had to be done manually, whereas with a product according to the inven~ion, applied to the vehicle wheel hub, combined with an electronic mileage counter in the vehicle wheel hub, automatic remote reading could be arranged.
DESCRIPTION OF THE DRAWINGS
The invention will now be described in more detail with re-ference to the accompanying figures, of which Figure 1 shows a block diagram of a known device, i.e. a transponder;
Figure 2 shows a conventional microstrip antenna in perspec-tive;
Figure 3 shows a view of a device according to the inven-tion;
.
Figure 4 shows a cross section of a device, integrated with a watch;
Figure 5 shows, in perspective, the device according to Figure 4 in the form of a wrist watch on a wrist;
Figure 6 and 7 show views of alternative embodiments of the antenna means according to the invention.
DESCRIPTION OF EMBODIMENTS OF THE INVENTION
Figure 1 shows a block diagram of a known transponder for information transmission, for example an identification tag, .
Wr~2/nl~3 2 ~ ~ 7 ~ PCT/SE91/~0479 and i~ based on the principle ~hat an incoming microwave signal is modified and reflected The antenna 1 receives a microwave frequency, fox example at 2.45 GHz, from en transmission/receiving unit and passes this signal onward to modulation circuits in the modulator-demodulator unit 2. Depending on ~he memory contents in the oscillator memory circuit 3 the modulator supplies informa-tion to the signal received by ~he transponder, and retrans-mits the modulated signal to the antenna 1, so that the in-formation is radiated out into space in front of the trans-ponder to the transmission/receiving unit so that it can read information rom the transponder.
In the case where data is to be written in the transponder a modulated microwave signal is transmitted to the antenna 1, demodulated in the circuit ~ and stored in a memory in the oscillator memory circuit 3.
The modulator circuits are controlled from the oscillator with a signal with low frequency compared with the microwave signal, for example at 32768 Hz. An output signal 4 from the oscillator can also suitably be used for the time signalling of the watch. A power source in the unit 5 supplies the oscillator-memory circuit 3 with voltage, and can also com-prise a clockwork if the invention is integrated with a watch.
Figure 2 shows a known conventional microstrip antenna, where a ~ielectric substrate 10 on one side has an antenna layer 11 of metal while a ground plane 12 of metal is loca-ted on the opposite side of the antenna layer. A battery 13 for the power supply of the transponder is located on the ground plane side, blocked out in the figure.
wr ~/01~3 ~ ~ ~ 7 3 ~ ~ PCT/SE91/~79 If an electric alternating voltage relative to the ground plane 12 is applied in or nearby the area 14 of the antenna layer, a standing wave will build up in the half-a-wave-length antenna in such a manner that radia~ion goes out from the electric field at the ends of the antenna layer, indi~
cated by the arrows 15, so that a wave is transplanted in the normal direction 16 of the antenna. In the rev~rse situation the radiation coming in towards the antenna layer causes an alternating voltage in the area 14.
~owever, this is the case only if the ground plane 12 is considerably larger than the antenna layer 11, or else the antenna will also radiate in the opposite direction to the perpendicular 16.
Figure 3 shows a transponder construction where an antenna patch 20 and a ground plane 21 are about the same size, and where an opening 22 has been made in the antenna layer to pro~ide space for components and microwave circuits. This an~enna type, if located in free space, will radiate about as much in both the directions of the perpendiculars. If, however, the antenna, as in the invention, is positioned nearby a reflection plane 23, typically smaller than one tenth of the air wave length from the antenna layer, the wave that is radiated out in the direction towards the reflection plane will be reflected in it and give a wave that interacts with the earlier described radiation out from the antenna layer. The exact proximity to the reflection plane is comparatively uncritical, which is why a trans-ponder with a straight ground plane can be mounted withoutdifficulty on a curved reflection surface.
It is to be noted that the radiation comes from the edges of the antenna layer, and that no real.radiation is created directly from the central parts of the antenna layer sur-W~ ~01953 2 ~ S V PCT/SEg~ 79 face. Therefore, ~his surface can be used for other purpo-ses, for example to mount the circuits 25-~6 in the opening 22 within the an~enna layer 20f which circuits are required to achieve an electric modulation, by means of a modulator diode 24, with information in the feed point o~ the antenna layer 29 and to detect incoming signals with a detector diode 28.
It is also possible, without disturbing the antenna func-tion, to place larger components such as a power source and the mechanic parts of a watch inside the radiating edge sur-faces of the antenna layer. These details can for reasons of symmetry be located optionally on ~he same side as the com-ponents in ~igure 3 or on that side of the ground plane 21 which faces the reflection surface 23. The transponder pro-vides ~he intended function irrespective of which of the surfaces 20 or 21 is positioned towards the reflection plane and irrespective of wh~ch side the power source or the mechanical parts of the watch are located on.
A signal received by the antenna layer 20 will give an electric alternating current field over the dielectric 30 towards the ground plane 21 in the feed point 29 of the an-tenna, which is located in, or beside, an area corresponding to the area 14 of the antenna layer in figure 2.
The received signal is conducted by the microstrip conductor 31 to a diode 24, whose impedance can be varied between dif-ferent values depending on what voltage is put on its termi-nals. In the example of the embodiment there is an inte-grated circuit 2S, which on its output terminal 32 emits a control voltage to the diode 24 which acts on its impedance.
One side of the diode, from a microwave viewpoint, is short-circuited to the ground plane 21 by the open quarter-wave conductor 33, and thus, depending on the output voltage from '2/01~3 15 PCr/SE9l~ ~ 7 the circuit 25, microwave-wise it will more or less connect the point 29 to the ground plane 21. The component 26 is a resonance element for an oscillator in the circuit 25, and is also suitably used for an oscillator in the circuit 25, and is also suitably used for the time keeping of the watch.
The above-described impedance variation in the diode 24 will cause that a wave front falling in towards the antenna layer 20 gives rise to a reflex modulated with information, where-by instantaneous phase position and amplitude are affectedby the impedance in the diode 24. Because the circuit 25 is caused to hold data information ~hat is allowed to afEect the impedance of the diode 24, for example by varying the frequency or the phase in an alternating voltage on the output texminal 32 in a manner representative of data information, a tr~nsponder has been achieved whose data at radiation can be read with the aid of an ex~ernal communi-cation unit. The communication unit is caused to receive and decode the signal that is reflected ~rom the transponder and modulated with data.
The connections 39 and 35 feed voltage to the transponder circuits from a power source, which is not shown in figure 3. Connection 34 has, because of space, been located in a cut in the external edge of the antenna layer 20, but this is of no importance for the function of the antenna because the antenna has a minimum of current in this point.
From an output terminal 38 on the circuit 25 second pulses are fetched for controlling the clockwork of a watch.
The diode 28 can be used for the am~litude detection of a signal that falls into the transponder, which signal, if it represents a data current to the transponder~ makes it pos-sible to write data into the circuit 25. The data signal ~7~
W ~2/~1~3 PCT/S~lJ~79 reaches the circui~ 25 via the capacitor 27, while thedirect conductor between the circuit 25 and detector diode 28 is used to bias the diode.
One further use of the diode 28 is as a rectifier of micro-wave pulses to be used to supply power to the transponder instead of, or as a complement to, its inbuilt power source.
Furthermore, the antenna layer can be provided with an addi-tional feed point so that the transponder, in a known man-ner, can function simultaneously in two polarisations ortho-gonal to each other.
In the case where it is desired to have a s~ronger reflected lS signal than can be achieved with the hitherto described de-vice, it is also possible ~hat the device receives a signal in one polarisation and retransmits the reflex in the other polarisation aft~r modulation and amplification. ~ecause the polarisations for reception and amplified retransmitted sig-nal are separate, the risks of crosstalk and self-oscilla-tion axe avoided.
The antenna layer opening can also be formed assymmetrically in various manners in order, for example, to make the trans-ponder polarisation circular.
It is also possible to use one of the diodes for writing in data in the transponder and the other diode for reading via two orthogonally polarised channels, independent of each other. Alternati~ely, one of the diodes can be used for rectification of incoming power supplying signals in the microwave area.
The diodes can also be integrated with the circuit 25.
PCTJS~ 79 ~v2/0~9~3 2~7~
The modulation circuits can also be formed in other ways, for example, by complementing or replacing the diode 24 and the micros~rip conductor 33 by other components.
In order to avoid demands for the transponder to be oriented in any specific manner relative to the rotational axis from the transmitter/receiver, it can be designed for transmis-sion and reception of circularly polarised waves. The trans-ponder, if it is linearly polarised, will in this case still be capable of being turned about said axis without signal drop out, as a cixcularly polarised wave comprises E fields in all directions at right angles from the direction of radiation.
lS An alternative embodiment of the transponder is to let the feed point 29 of the antenna layer, via a through-connection conductor, stand in connection with circuits located on the other side and on their own carrier. This solution can be used when there is a need for more space than is available in the opening 22 without the antenna function being disturbed.
Figure 9 shows the invention integrated with a wrist watch with the antenna l~yer 20 turned inwards toward the wrist and where the transponder and its ground plane 21 constitute a unit integrated with the clock face. In a manner described earlier, what remains of the signal towards the watch case 42 and the wrist 43 will after reflection interact with the direct radiation out fro~ the transponder.
Battery 90, clockwork 41, electronic circuits and microwave circuits are mounted on the side of the antenna layer, in-side the external limiting line of the antenna layer.
W~2/~19~3 ~ ~ $ ~ PCT/S~I/M~79 Figure 5 shows a view of a wrist watch, where, for example, the ground plane and clock face constitute an integrated unit 50. An indicator 51 can, besides showing the time, give indications that are related to information transmission, memory contents, status and other information.
Integrated with functions of similar type that is used in transaction cards, for example according to ISO 7~16, trans-actions can be effected with a wrist mounted ~ransponder, and in addition the result can be displayed on an indicator 51 that is controlled from the electronic circui~s of the watch.
In simpler applications the transponder can be designed to store information according to the widely spread standards that apply to many credit cards and tickets with magnetic strips, and in many applications directly replace these in that the magnetic card reader is r~placed by a microwave based write/read unit for the transponder.
Unauthorized access to the transponder can be prevented in that its function is normally locked. Release can be effec-ted in that one or more operational means 52 on the wrist watch are acted upon, possibly in a manner which is specific for the watch.
In the case where a very hi.gh degree of security is requi-red, e.g. if the device is to store value related informa-tion, such as electronic punches or money, it can be provi-ded with means that provides sufficient safety againstunauthorised access. This can be effected in a similar manner as that used for pay cards of magnetic strip type, for electronic memory cards or for microprocessor cards. In the latter case a microprocessor with coding functions, for W~ '2/019~3 ~ r~ PCT/SE9l/~79 example the standardized DES and RSA algorithms, are implemented.
The antenna layer can also be given another embodiment, for example rectangular, without having its function principle altered. Furthermore, other antenna types than patch anten-nae can be chosen, e.g. with greater ban~ width but somewha~
less effective microstrip dipoles. The advantage with such a type of an~enna could be that it can be made to function at the same time at 2.45 and 5.7 GHz. -Figure 6 shows such an embodiment where the antenna layer isconstituted by a folded dipole on the ground plane in :micro-strip technique, which in its function partly resembles the patch antenna. The dipole element is constituted by the metal surface 60 which via a dielectric substrate 30 stands in connection with a ground plane 21, and where the unit is mounted on a reflected surface 23. The modulation of an in-coming microwave signal is effected with the aid of compo-nents which are connected to the antenna layer in the feedpoints 63 in a similar manner as has been described earlier.
Figure 7 shows a~ alternative embodiment of the transponder where an array 71 of two folded microstrip dipoles acts to-wards the ground plane 21. The microwave signal is connectedin the feed points 72 and the unit is mounted on a reflec-ting surface 23.
The device can also be provided with a mare sensitive recei-ver than with the diode detector 28 that has been shown in earlier examples of embodiments, and can be formed to act on an acoustic means integrated in a known way with the watch, being used for microwave based pager applications, whereby on receiving a special code via the.microwave link it emits w~ "~Jo19~3 2 Gl 8 ~ 9 8 ~ Pcr/sEgt/on479 ~o an observation signal to the carrier and possibly shows re-lated information on the indicator.
The invention is not limited to the examples of embodiments S as described here, and can be varied wi~hin the scope of the presented claims.
Claims (19)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A device for information transmission, a so-called transponder, for receiving a first microwave signal, modulation and coding, and retransmitting a second microwave signal, comprising at least one antenna means made in microstrip technique, characterized in that the antenna means comprises an antenna layer, acting towards a ground plane, the antenna layer and the ground plane having principally equal area, and that the device further comprises a reflex means, arranged next to, or at a distance of at most 1/6 of the air wave length of the first microwave signal from, the radiating edges of the antenna layer, arranged to reflect the second microwave signal that goes out from the radiating edges of the antenna layer and the ground plane edges, so that an antenna lobe, directional from the antenna means, comprised of a directly transmitted microwave signal and a reflected microwave signal, is obtained.
2. A device according to claim 1, characterized in that the relation between a first radius of a circle, circumscribing the antenna layer and a second radius of a circle, circumscribing the ground plane, lies in the interval 0.6 to 1.7.
3. A device according to claim 1 or 2, characterize d in that the transponder components with relatively large extension, such as power source and/or microstrip conductors entirely or partly are located within the innermost of the cylinder walls that can be conceived to be circumscribed by the antenna layer or ground plane.
W???/01953 PCT/SE91/00479
W???/01953 PCT/SE91/00479
4. A device according to any one of claims 1 to 3, cha-racterized in that the antenna means consists of a patch antenna (20), which via a substrate of a die-lectric material (30) interacts with a ground plane (21).
5. A device according to any one of claims l to 3, cha-racterized in that the antenna means consists of a single (60) or double (71) folded dipole antenna, which via a substrate of a dielectric material (30) interacts with a ground plane (21).
6. A device according to any preceding claim, charac-terized in that its microstrip conductors (31, 33, 36, 37) are placed entirely or partly in one or more openings (22) within the antenna layer (20) of the device and thereby interact through the same substrate (30) with the same ground plane (21) as the antenna layer (20), in which arrangement there are no electric through connections through the substrate (30).
7. A device according to any preceding claim, charac-terized in that the device is designed as a compact box, intended to be carried by a person in direct or close body contact.
8. A device according to claim 7, characterize d in that said reflex means consists of the bottom of the box.
9. A device according to claim 7, characterized in that said reflex means consists of said person's body surface.
WO??/01953 PCT/SE91/00479
WO??/01953 PCT/SE91/00479
10. A device according to any one of claims 7 to 9, cha-racterized in that the transponder has been inte-grated with a watch to be carried at a person's wrist, said reflex means consisting of the clock case.
11. A device according to any one of claims 7 to 9, cha-racterized in that the transponder has been inte-grated with a watch to be carried at a person's wrist, said reflex means consisting of the person's wrist sur-face.
12. A device according to claim 10 or 11, character-ized in that the ground plane (21) has been formed integrated with the visible clock face and that the an-tenna layer and other components such as clockwork (41), power source (40), electronic components (24, 26) and microstrip conductors (31, 33, 36, 37) have been positioned between the clock face and the clock case.
13. A device according to any one of claims 10 to 12, characterized in that a chip is used in common for controlling the clockwork (41) or other time indicator in the watch in order to store a code which is unique for the watch, and contributing to the information transmission to and from the transponder.
14. A device according to any one of claims 10 to 13, characterized in that the transponder is arranged to store and/or transmit, directly or indirectly, time functions inbuilt in the watch.
15. A device according to any one of claims 7 to 14, cha-racterized in that it indicates the result of transactions on at least one indicator means (51) via WO??/01953 PCT/SE91/00479 the first and/or second microwave signal, such as balance and status information.
16. A device according to any one of claims 7 to 15, cha-racterized in that it is arranged to admit certain transactions only during a predetermined time interval, initiated by at least one operational means (52) in the device being acted upon, possibly in a manner which is specific for the watch.
17. A device according to any one of claims 7 to 16, cha-racterized in that the device is arranged to admit certain data transactions via the first and/or second microwave signal entirely or partly coded, for example according to DES or RSA.
18. A device according to any one of claims 7 to 17, cha-racterized in that, on receiving a first microwave signal transmitting a code which is preprogrammed in the transponder, it is arranged to give an acoustic signal and possibly also give visual information on at least one indicator means (51).
19. A device according to any one of claims 1 to 6, cha-racterized in that said reflex means consists of a surface, especially of metal, on which the device is attached.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE9002493-6 | 1990-07-24 | ||
| SE9002493A SE9002493L (en) | 1990-07-24 | 1990-07-24 | VEHICLE DEVICE MAINTAINS POSITIONING BY AUTOMATIC FUELING |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2087980A1 true CA2087980A1 (en) | 1992-01-25 |
Family
ID=20380041
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002087980A Abandoned CA2087980A1 (en) | 1990-07-24 | 1991-07-05 | Device for information transmission |
Country Status (10)
| Country | Link |
|---|---|
| US (1) | US5414427A (en) |
| EP (1) | EP0553094B1 (en) |
| JP (1) | JPH06501595A (en) |
| AT (1) | ATE147864T1 (en) |
| AU (1) | AU650470B2 (en) |
| CA (1) | CA2087980A1 (en) |
| DE (1) | DE69124259T2 (en) |
| FI (1) | FI930254A0 (en) |
| SE (1) | SE9002493L (en) |
| WO (1) | WO1992001953A1 (en) |
Families Citing this family (62)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5581257A (en) * | 1991-09-24 | 1996-12-03 | Gordian Holding Corporation | Radio frequency automatic identification system |
| DE69324132T2 (en) * | 1992-01-23 | 1999-10-28 | Saab Scania Combitech Ab Joenk | WIRELESS INFORMATION TRANSFER DEVICE |
| AU3465293A (en) * | 1992-01-23 | 1993-09-01 | Saab-Scania Combitech Aktiebolag | Device for information transfer |
| US5497140A (en) * | 1992-08-12 | 1996-03-05 | Micron Technology, Inc. | Electrically powered postage stamp or mailing or shipping label operative with radio frequency (RF) communication |
| USRE42773E1 (en) | 1992-06-17 | 2011-10-04 | Round Rock Research, Llc | Method of manufacturing an enclosed transceiver |
| DE4319878A1 (en) * | 1992-06-17 | 1993-12-23 | Micron Technology Inc | High frequency identification system card - has integrated circuit chip or carrier layer sealed by top layer and coupled to batteries and antenna system |
| US5776278A (en) * | 1992-06-17 | 1998-07-07 | Micron Communications, Inc. | Method of manufacturing an enclosed transceiver |
| US7158031B2 (en) * | 1992-08-12 | 2007-01-02 | Micron Technology, Inc. | Thin, flexible, RFID label and system for use |
| ZA941671B (en) * | 1993-03-11 | 1994-10-12 | Csir | Attaching an electronic circuit to a substrate. |
| US5534872A (en) * | 1993-06-30 | 1996-07-09 | Casio Computer Co., Ltd. | Portable radio signal detecting system |
| FR2726127B1 (en) * | 1994-10-19 | 1996-11-29 | Asulab Sa | MINIATURIZED ANTENNA FOR CONVERTING AN ALTERNATIVE VOLTAGE TO A MICROWAVE AND VICE-VERSA, PARTICULARLY FOR WATCHMAKING APPLICATIONS |
| US5956259A (en) * | 1995-12-08 | 1999-09-21 | Gilbarco Inc. | Intelligent fueling |
| US6169938B1 (en) | 1995-12-08 | 2001-01-02 | Marconi Commerce Systems Inc. | Transponder communication of ORVR presence |
| DK107396A (en) * | 1996-10-01 | 1996-10-01 | Triax As | Bracket for mounting a satellite dish |
| JPH10197662A (en) * | 1996-12-28 | 1998-07-31 | Casio Comput Co Ltd | Receiver device |
| JP3297904B2 (en) * | 1997-01-09 | 2002-07-02 | 株式会社 オーヴァ | Individual recognition device for traveling toys using transponder |
| US5988510A (en) * | 1997-02-13 | 1999-11-23 | Micron Communications, Inc. | Tamper resistant smart card and method of protecting data in a smart card |
| SE508513C2 (en) * | 1997-02-14 | 1998-10-12 | Ericsson Telefon Ab L M | Microstrip antenna as well as group antenna |
| SE508537C2 (en) * | 1997-02-14 | 1998-10-12 | Ericsson Telefon Ab L M | Double-polarized antenna for receiving and transmitting electromagnetic signals |
| US5868179A (en) * | 1997-03-04 | 1999-02-09 | Gilbarco Inc. | Precision fuel dispenser |
| US6329213B1 (en) | 1997-05-01 | 2001-12-11 | Micron Technology, Inc. | Methods for forming integrated circuits within substrates |
| US6078888A (en) * | 1997-07-16 | 2000-06-20 | Gilbarco Inc. | Cryptography security for remote dispenser transactions |
| US6339385B1 (en) | 1997-08-20 | 2002-01-15 | Micron Technology, Inc. | Electronic communication devices, methods of forming electrical communication devices, and communication methods |
| US6810304B1 (en) | 1997-09-26 | 2004-10-26 | Gilbarco Inc. | Multistage ordering system for a fueling and retail environment |
| US6098879A (en) * | 1997-09-26 | 2000-08-08 | Gilbarco, Inc. | Fuel dispensing system providing customer preferences |
| US6574603B1 (en) | 1997-09-26 | 2003-06-03 | Gilbarco Inc. | In-vehicle ordering |
| US6882900B1 (en) | 1997-09-26 | 2005-04-19 | Gilbarco Inc. | Fuel dispensing and retail system for providing customer selected guidelines and limitations |
| US6470233B1 (en) | 1997-09-26 | 2002-10-22 | Gilbarco Inc. | Fuel dispensing and retail system for preventing use of stolen transponders |
| US6263319B1 (en) | 1997-09-26 | 2001-07-17 | Masconi Commerce Systems Inc. | Fuel dispensing and retail system for providing a shadow ledger |
| US5890520A (en) * | 1997-09-26 | 1999-04-06 | Gilbarco Inc. | Transponder distinction in a fueling environment |
| US6070156A (en) * | 1997-09-26 | 2000-05-30 | Gilbarco Inc. | Providing transaction estimates in a fueling and retail system |
| US6073840A (en) * | 1997-09-26 | 2000-06-13 | Gilbarco Inc. | Fuel dispensing and retail system providing for transponder prepayment |
| US6157871A (en) * | 1997-09-26 | 2000-12-05 | Marconi Commerce Systems Inc. | Fuel dispensing system preventing customer drive-off |
| US6118379A (en) * | 1997-12-31 | 2000-09-12 | Intermec Ip Corp. | Radio frequency identification transponder having a spiral antenna |
| US6215402B1 (en) * | 1998-03-13 | 2001-04-10 | Intermec Ip Corp. | Radio frequency identification transponder employing patch antenna |
| US6313737B1 (en) | 1998-06-23 | 2001-11-06 | Marconi Commerce Systems Inc. | Centralized transponder arbitration |
| US6381514B1 (en) | 1998-08-25 | 2002-04-30 | Marconi Commerce Systems Inc. | Dispenser system for preventing unauthorized fueling |
| JP2002524124A (en) * | 1998-09-04 | 2002-08-06 | ウルフ リサーチ プロプライエタリー リミテッド | Medical implantation system |
| US6089284A (en) * | 1998-09-24 | 2000-07-18 | Marconi Commerce Systems Inc. | Preconditioning a fuel dispensing system using a transponder |
| US8538801B2 (en) | 1999-02-19 | 2013-09-17 | Exxonmobile Research & Engineering Company | System and method for processing financial transactions |
| JP3394214B2 (en) * | 1999-07-12 | 2003-04-07 | 三菱電機株式会社 | Circularly polarized radar transponder and lifesaving device |
| US6273339B1 (en) | 1999-08-30 | 2001-08-14 | Micron Technology, Inc. | Tamper resistant smart card and method of protecting data in a smart card |
| KR100370800B1 (en) | 2000-06-09 | 2003-02-05 | 엘지.필립스 엘시디 주식회사 | method for fabricating array substrate for LCD |
| US7082406B1 (en) | 2000-06-22 | 2006-07-25 | Gilbarco Inc. | Multi-stage accounting system for a fueling environment |
| GB2370640A (en) * | 2000-08-08 | 2002-07-03 | Transense Technologies Plc | SAW device with integral patch antenna |
| DE10041801C2 (en) * | 2000-08-25 | 2003-09-04 | Siemens Ag | Anti-theft protection system for a motor vehicle and method for operating the anti-theft system |
| US6545606B2 (en) | 2001-01-25 | 2003-04-08 | The United States Of America As Represented By The Secretary Of The Navy | Device and method for alerting to the need to recover something, identifying it, and determining its location for purposes of recovery |
| JP2003035786A (en) | 2001-07-25 | 2003-02-07 | Mitsubishi Materials Corp | Wrist watch with built-in tag |
| EP2202842B1 (en) * | 2001-09-07 | 2011-06-29 | Seiko Epson Corporation | Electronic timepiece with a contactless data communication function, and a contactless data communcation system |
| DE10207049A1 (en) * | 2002-02-20 | 2003-09-04 | Junghans Uhren Gmbh | Notrufsender |
| DE60220927T2 (en) * | 2002-11-13 | 2008-04-03 | Mitsubishi Materials Corp. | Wristwatch with an RFID tag |
| DE10328383A1 (en) * | 2003-06-24 | 2005-01-20 | Siemens Ag | A method for authorizing an information provider to a method for communicating information and switching information and switching equipment |
| JP4551641B2 (en) * | 2003-09-29 | 2010-09-29 | シチズンホールディングス株式会社 | Portable electronic device with non-contact data communication function |
| JP4644054B2 (en) * | 2005-07-04 | 2011-03-02 | 住友ナコ マテリアル ハンドリング株式会社 | Pallet with RFID tag and forklift |
| JP4437475B2 (en) | 2006-01-31 | 2010-03-24 | 富士通株式会社 | Folded dipole antenna and tag using the same |
| DE102007027539A1 (en) * | 2007-06-15 | 2008-12-18 | Giesecke & Devrient Gmbh | transponder system |
| JP5412741B2 (en) * | 2008-03-26 | 2014-02-12 | 富士ゼロックス株式会社 | Wireless transceiver |
| JP2011097431A (en) | 2009-10-30 | 2011-05-12 | Seiko Epson Corp | Arm-mounted electronic apparatus |
| EP2367021A1 (en) * | 2010-03-17 | 2011-09-21 | The Swatch Group Research and Development Ltd. | Method and system for locating objects |
| FI20105507A0 (en) * | 2010-05-10 | 2010-05-10 | Marisense Oy | WIRELESS ELECTRONIC SHELF |
| US9355349B2 (en) | 2013-03-07 | 2016-05-31 | Applied Wireless Identifications Group, Inc. | Long range RFID tag |
| JP5796670B2 (en) * | 2014-08-20 | 2015-10-21 | セイコーエプソン株式会社 | Arm-mounted electronic device |
Family Cites Families (19)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SE417026C (en) * | 1976-09-02 | 1982-03-21 | Inst For Mikrovagsteknik Vid T | DEVICE FOR REGISTERING A FIRST TYPE OF FORMAL, WHICH RELATIVELY MOVES ANOTHER TYPE OF FORMAL |
| US4242661A (en) * | 1975-03-27 | 1980-12-30 | Stifelsen Institutet for Mikrovagsteknik Vid Tekniska Hogskolan i Stockholm | Device for registration of objects |
| US4442590A (en) * | 1980-11-17 | 1984-04-17 | Ball Corporation | Monolithic microwave integrated circuit with integral array antenna |
| JPS58148526A (en) * | 1982-02-26 | 1983-09-03 | Mitsubishi Electric Corp | Device for rescue signal |
| FR2527870A1 (en) * | 1982-05-27 | 1983-12-02 | Telemecanique Electrique | Microwave transponder for transceiver interrogation - includes microwave circuits built on dielectric surfaces to provide unique response coded signal |
| US4600906A (en) * | 1982-12-03 | 1986-07-15 | Raytheon Company | Magnetically tuned resonant circuit wherein magnetic field is provided by a biased conductor on the circuit support structure |
| US4771291A (en) * | 1985-08-30 | 1988-09-13 | The United States Of America As Represented By The Secretary Of The Air Force | Dual frequency microstrip antenna |
| US4782345A (en) * | 1986-07-29 | 1988-11-01 | Amtech Corporation | Transponder antenna |
| FR2609813B1 (en) * | 1987-01-19 | 1989-03-03 | Midi Robois | IDENTIFICATION AND / OR LOCATION METHOD AND SYSTEM, AND BEACON FOR IMPLEMENTING SAID METHOD |
| US4813025A (en) * | 1987-06-12 | 1989-03-14 | David B. Rowland | Safety alert and locating system |
| US4908615A (en) * | 1987-06-26 | 1990-03-13 | Texas Instruments Incorporated | Traffic light control system and method |
| GB2211357A (en) * | 1987-09-23 | 1989-06-28 | Philips Electronic Associated | Integrated millimetre-wave transceiver |
| EP0308964B1 (en) * | 1987-09-24 | 1994-05-04 | Fujitsu Limited | Radio-frequency identification system |
| US4855749A (en) * | 1988-02-26 | 1989-08-08 | The United States Of America As Represented By The Secretary Of The Air Force | Opto-electronic vivaldi transceiver |
| US4933680A (en) * | 1988-09-29 | 1990-06-12 | Hughes Aircraft Company | Microstrip antenna system with multiple frequency elements |
| US5001492A (en) * | 1988-10-11 | 1991-03-19 | Hughes Aircraft Company | Plural layer co-planar waveguide coupling system for feeding a patch radiator array |
| US5212494A (en) * | 1989-04-18 | 1993-05-18 | Texas Instruments Incorporated | Compact multi-polarized broadband antenna |
| JP2533800B2 (en) * | 1989-06-02 | 1996-09-11 | 山武ハネウエル株式会社 | Microwave response device |
| US5025247A (en) * | 1990-04-09 | 1991-06-18 | Banks James C | Portable emergency alert system |
-
1990
- 1990-07-24 SE SE9002493A patent/SE9002493L/en not_active IP Right Cessation
-
1991
- 1991-07-05 DE DE69124259T patent/DE69124259T2/en not_active Expired - Lifetime
- 1991-07-05 AU AU82802/91A patent/AU650470B2/en not_active Expired
- 1991-07-05 WO PCT/SE1991/000479 patent/WO1992001953A1/en active IP Right Grant
- 1991-07-05 AT AT91913906T patent/ATE147864T1/en not_active IP Right Cessation
- 1991-07-05 JP JP3512868A patent/JPH06501595A/en active Pending
- 1991-07-05 EP EP91913906A patent/EP0553094B1/en not_active Expired - Lifetime
- 1991-07-05 US US07/961,939 patent/US5414427A/en not_active Expired - Lifetime
- 1991-07-05 CA CA002087980A patent/CA2087980A1/en not_active Abandoned
-
1993
- 1993-01-22 FI FI930254A patent/FI930254A0/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| FI930254A (en) | 1993-01-22 |
| ATE147864T1 (en) | 1997-02-15 |
| AU650470B2 (en) | 1994-06-23 |
| AU8280291A (en) | 1992-02-18 |
| FI930254A0 (en) | 1993-01-22 |
| EP0553094B1 (en) | 1997-01-15 |
| SE465391B (en) | 1991-09-02 |
| DE69124259T2 (en) | 1997-04-30 |
| DE69124259D1 (en) | 1997-02-27 |
| US5414427A (en) | 1995-05-09 |
| EP0553094A1 (en) | 1993-08-04 |
| WO1992001953A1 (en) | 1992-02-06 |
| SE9002493L (en) | 1991-09-02 |
| JPH06501595A (en) | 1994-02-17 |
| SE9002493D0 (en) | 1990-07-24 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP0553094B1 (en) | Device for information transmission | |
| US9767331B2 (en) | Methods and apparatus for preserving privacy in an RFID system | |
| CA2218985C (en) | Electronic license plate architecture | |
| US5995048A (en) | Quarter wave patch antenna | |
| EP1675216B1 (en) | Method of attaching wireless communication devices | |
| TW497085B (en) | Passive transponder identification system and credit card type transponder | |
| US7800503B2 (en) | Radio frequency identification (RFID) tag antenna design | |
| EP0623219B1 (en) | Device for wireless transfer of information | |
| US7411507B2 (en) | Metal housing with integral antenna for RFID reader/writer | |
| US6121878A (en) | System for controlling assets | |
| US7501947B2 (en) | RFID tag with small aperture antenna | |
| US6992634B2 (en) | Antenna device commonly used for two frequencies | |
| MX2013012902A (en) | Rfid switch tag. | |
| US6246356B1 (en) | Omnidirectional transponder | |
| WO1993015417A1 (en) | Device for information transfer | |
| RU2776398C2 (en) | Vehicle identification means |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |