WO2003050915A1

WO2003050915A1 - Communication device with front-end antenna integration

Info

Publication number: WO2003050915A1
Application number: PCT/US2002/039173
Authority: WO
Inventors: Walter John Keller; Jesada Sivaraks
Original assignee: Protura Wireless, Inc.
Priority date: 2001-12-06
Filing date: 2002-12-06
Publication date: 2003-06-19
Also published as: AU2002362091A1

Abstract

A communication device operating for exchanging energy in a plurality of bands of radiation frequencies includes a plurality of compressed antennas, each antenna for operating with one or more of the bands of radiation frequencies. The communication device also includes a transmitter section for processing transmitter signals, a receiver section for processing receiver signals and connection means connecting the plurality of compressed antennas to the transmitter section and the receiver section. In some embodiments, the communication device includes one or more diplexers to switch antennas from one band to another. In some embodiments, the communication device includes one or more duplexers to switch antennas between the receiver section and the transmitter section.

Description

TITLE

COMMUNICATION DEVICE WITH FRONT-END ANTENNA INTEGRATION

BACKGROUND OF THE INVENTION

The present invention relates to the field of communication devices that communicate using radiation of electromagnetic energy and particularly relates to antennas and front ends for such communication devices, particularly for communication devices carried by persons or devices otherwise benefitting from small-sized antennas.

The front end of a cellular telephone is an expensive and space consuming section. Typically, antennas used for cellular multi-band communication devices are broadband and diplexers are needed to separate bands and duplexers are needed to separate receive (Rx) and transmit (Tx) portions of each band. In a standard dual-band cellular telephone design there is typically one diplexer and two duplexers in line between the antem a and the telephone's active components including Low Noise Amplifiers (LNA) and RF chipsets. The total cost of these components is frequently as much as 10% or more of the total cost of the communication device. A quad-band telephone will typically have one diplexer, two RF switches and four duplexers further increasing the complexity and cost of front-end designs.

Communication Antennas Generally. In communication devices and other electronic devices, antennas are elements having the primary function of transferring energy to or from the electronic device through radiation. Energy is transferred from the electronic device into space or is received from space into the electronic device. A transmitting antemia is a structure that forms a transition between guided waves contained within the electronic device and space waves traveling in space external to the electronic device. A receiving antenna is a structure that forms a transition between space waves traveling external to the electronic device and guided waves contained witliin the electronic device. Often the same antenna operates both to receive and transmit radiation energy.

J.D. Kraus "Electromagnetics", 4th ed., McGraw-Hill, New York 1991, Chapter 15 Antennas and Radiation indicates that antennas are designed to radiate (or receive) energy. Antennas act as the transition between space and circuitry.

They convert photons to electrons or vice versa. Regardless of antenna type, all involve the same basic principal that radiation is produced by accelerated (or decelerated) charge. The basic equation of radiation may be expressed as follows:

IL =Qv (Am/s) where:

I = time changing current (A/s) L= length of current element (m) Q= charge (C) v= time-change of velocity which equals the acceleration of the charge (m/s )

The radiation is perpendicular to the direction of acceleration and the radiated power is proportional to the square of IL or Qv. A radiated wave from or to an antenna is distributed in space in many spatial directions. The time it takes for the spatial wave to travel over a distance r into space between an antenna point, P_a, at the antenna and a space point, P, at a distance r from the antenna point is r/c seconds where r = distance (meters) and c = free space velocity of light ( = 3 X 10⁸ meters/sec). The quantity r/c is the propagation time for the radiation wave between the antenna point P_a and the space point P_s.

An analysis of the radiation at a point P at a time t, at a distance r caused by an electrical current / in any infinitesimally short segment at point P_a of an antenna is a function of the electrical current that occurred at an earlier time [t-r/c] in that short antenna segment. The time [t-r/c] is a retardation time that accounts for the time it takes to propagate a wave from the antenna point P_a at the antenna segment over the distance r to the space point P.

For simple antenna geometries, antennas are typically analyzed as a connection of infinitesimally short radiating antenna segments and the accumulated effect of radiation from the antenna as a whole is analyzed by accumulating the radiation effects of each antenna segment. The radiation at different distances from each antenna segment, such as at any space point P_s, is determined by accumulating the effects from each infinitesimally short antenna segment at point P_a of the antenna at the space point P. The analysis at each space point P is mathematically complex because the parameters for each segment of the antenna may be different. For example, among other parameters, the frequency phase of the electrical current in each antenna segment and distance from each antenna segment to the space point P can be different. A resonant frequency, of an antenna can have many different values as a function, for example, of dielectric constant of material surrounding antenna, the type of antenna and the speed of light.

In general, wave-length, λ , is given by λ = c/f= cT where c = velocity of light (=3 X 10⁸ meters/sec), / = frequency (cycles/sec), T = II f= period (sec). Typically, the antenna dimensions such as antenna length, A_l3 relate to the radiation wavelength λ of the antenna. The electrical impedance properties of an antenna are allocated between a radiation resistance, R_, and an ohmic resistance, R„. The higher the ratio of the radiation resistance, R_, to the ohmic resistance, R₀ the greater the radiation efficiency of the antenna. Antennas are frequently analyzed with respect to the near field and the far field where the far field is at locations of space points P where the amplitude relationships of the fields approach a fixed relationship and the relative angular distribution of the field becomes independent of the distance from the antenna. Antenna Types. A number of different antemia types are well known and include, for example, loop antennas, small loop antennas, dipole antennas, stub antennas, conical antennas, helical antennas and spiral antennas. Such antenna types have often been based on simple geometric shapes. For example, antenna designs have been based on lines, planes, circles, triangles, squares, ellipses, rectangles, hemispheres and paraboloids. The two most basic types of electromagnetic field radiators are the magnetic dipole and the electric dipole. Small antennas, including loop antennas, often have the property that radiation resistance, R_, of the antenna decreases sharply when the antemia length is shortened. Small loops and short dipoles typically exhibit radiation patterns of l/2λ and l/4λ, respectively. Ohmic losses due to the ohmic resistance, R₀ are minimized using impedance matching networks. Although impedance matched small circular loop antennas can exhibit 50% to 85% efficiencies, their bandwidths have been narrow, with very high Q, for example, Q>50. Q is often defined as (transmitted or receiyed frequency)/ (3 dB bandwidth).

An antenna goes into resonance where the impedance of the antenna is purely resistive and the reactive component goes to 0. Impedance is a complex number consisting of real resistance and imaginary reactance components. A matching network can be used to force resonance by eliminating the reactive component of impedance for a particular frequency.

Electric Dipole. A linear antenna is often considered as a large number of very short conductor elements connected in series. For purpose of explanation, the minimum element of linear antemia is a short electric dipole (see FIG. 14). The electric dipole is "short" in the sense that its physical length (L) is much smaller than the wavelength (λ) of the signal exciting it, that is, L/λ «1. For purpose of analysis, the two ends of a electric dipole are considered plates with capacitive loading. These plates and the L « λ condition, provide a basis for assuming a uniform electric current I along the entire length of the electric dipole. Also, the electric dipole is assumed to be energized by a balanced transmission line, is assumed to have negligible radiation from the end plates, and is assumed to have a very thin diameter, d, that is, d « L, such that the electric dipole consists simply of a thin conductor of length L carrying a uniform current I with point charges +q and -q at the ends. With such an assumed structure, the current /and charge q are related by:

dt

For any point P_a on the electric dipole, the electric and magnetic fields at a point P a distance r from the point P_a as a result of the uniform electric current I tlirough the element are represented as vector components in a spherical polar coordinate system having orthogonal XYZ axes (see FIG. 14 and FIG. 15). For an electric dipole normal to the XY plane, the projection of the vector r in the XY- plane has an angle of φ with respect to the XZ plane and an angle of θ from the Z axis normal to the XY plane.

The general equation of both electric (E_r, E_θ, E_φ) and magnetic (H_r, H_θ, H , ) components at point P, offset from point P_aby vector r, are as follows:

[I]Lcosθ

E =

2πε V cr² jωr²

[T L smθ j jω _, 1

2πε c cr jωr

where components E_φ , H,., H_θ are zero for eveiy P and where:

[I\ = l₀e^iω(l- ^/c)

I₀ = Peak value in time of current (uniform along dipole) c = Velocity of light

L = Length of dipole r = Distance from dipole to observation point

Considering the above equations, the 1/r term is called the induction field or intermediate field component and the 1/r³ term represents the electrostatic field ox near field component. These two terms are significant only very close to the dipole and therefore are considered in the near field region of the antemia. For very large r, the 1/r² and 1/r³ terms can be neglected leaving only the 1/r term as being significant. This 1/r terms is called the far field. Consequently, the revised equations of electric and magnetic components at the far field are given as:

j60;r|J]sm0 L

E_a

_.^■[/] sin 0 L

H,

2r λ

Examining the E_θ and H_φ components in the far field, it can be seen that E_θ and Hψ are in time phase (with respect to each other) in the far field, and that the field patterns of both are proportional to sin(θ) but independent of φ. The space patterns of those fields are a figure of revolution and doughnut-shaped in three dimensions (see FIG. 18) fιgure-8 shaped in two dimensions (see FIG. 19). Note that the near field patterns for E_θ and H_φ are proportional to only sin(θ); so, the shapes of the near field patterns are the same as for the far field and that the E_r component in the near field is proportional to cos#

Magnetic Dipole. A magnetic dipole is the dual of the electric dipole and hence an analogy to the electric dipole can be used for purpose of analysis. A magnetic dipole is a short circular antenna element arrayed to form a magnetic field and is represented by a very short loop (see FIG. 16) in the XY-plane. For purpose of analysis, the magnetic dipole conducts an electric current I that causes a magnetic current (I_m) normal to the plane of the magnetic dipole. The magnetic current (I_m) of the magnetic dipole is the dual of the electric current (I) of the electric dipole. The analysis of the far field pattern of a magnetic dipole (see FIG. 16) is similar to the analysis of the far field pattern of the electric dipole. The only difference is that the electric current I is replaced by a magnetic current I_m and the electric field is replaced by magnetic field.

For purpose of analysis, the magnetic dipole is a small loop of area A carrying a uniform in-phase electric current /which is the dual of the electric dipole of length L in the far field. The fields of the short magnetic dipole are the same as the fields of a short electric dipole with the E and H fields and / and I_m currents interchanged as follows:

Considering the equation of far field pattern for magnetic dipole, both H_θ and E_φ are proportional to sin(θ) but independent of φ. Consequently, the far field pattern of the H_θ and E_φ components of a magnetic dipole are doughnut-shaped in three dimensions (see FIG. 18) and figure-8 circular in cross section (see FIG. 19). Applying Relationship Between a Loop and Magnetic Dipole. The relationship between the length of magnetic dipole and a small loop antemia are used to derive the far field pattern equation of a small loop antenna. Accordingly, [J L = -j240[i] is used in the above far-field equation for a small magnetic dipole and the far field equations of a small loop antenna are written as:

120^² [/]sing A

E, = r λ²

[I] sin 9 A

^H° ~ r λ

where [ Άi] = I giω(t-r/c)

= Peak value in time of current (uniform along dipole) c = Velocity of light

A = Area of loop antenna

X = Distance from Loop to observation point

The above far field equations are good approximations for loops up to 0J wavelength in diameter and dipoles up to 0J wavelength long. A comparison of far fields between small electric dipoles and small loop antennas are given in the following table:

From the table, the presence of the operator in the dipole expressions and its absence in the loop equations indicate that the fields of the electric dipole and of the loop are in time phase quadrature. This quadrature relationship is a fundamental difference between the fields of pure magnetic dipoles (circular loops) and electric dipoles (linear elements).

The analytical models for showing the fields of antennas that are larger than short dipoles are mathematically complex even when the antennas have a high degree of symmetry. Even more difficulty of analysis arises when antennas have irregular shapes and require operations over multiple bands or with high bandwidth. In the mobile communications environment, antennas are frequently placed inside the case of the communication device in close proximity to conductive components. In such close proximity, the antenna near and intermediate fields become significant and cannot be neglected to determine far field radiation patterns . For these reasons, the analytical models for short dipoles do not adequately predict the behavior of antennas needed for new communication devices. Fundamentally new designs and design techniques are needed to address the new environment of personal or otherwise small communication devices.

Personal communication devices, when in use, are usually located close to an ear or other part of the human body. Accordingly, use of personal communication devices subjects the human body to radiation. The radiation absorption from a communication device is measured by the rate of energy absorbed per unit body mass and this measure is known as the specific absorption rate (SAR). Antennas for personal communication devices are designed to have low peak SAR values so as to avoid absorption of unacceptable levels of energy, and the resultant localized heating by the body.

For personal communication devices, the human body is located in the near-field of ^'an antenna where much of the electromagnetic energy is reactive and electrostatic rather than radiated. Consequently, it is believed that the dominant cause of high SAR for personal communication devices is from reactance and electric field energy of the near field. Accordingly, the reactance and electrostatic fields of personal communication devices need to be controlled to minimize SAR. Regardless of the reasons, low SAR is a desirable parameter along with the other important parameters for antennas in communication devices. In consideration of the above background, there is a need for improved antennas and front ends suitable for communication devices and other devices needing small and compact antennas.

SUMMARY The present invention is a communication device operating for exchanging energy in a plurality of bands of radiation frequencies and includes a plurality of compressed antennas, each antemia for operating with one or more of the bands of radiation frequencies. The communication device also includes a transmitter section for processing transmitter signals, a receiver section for processing receiver signals and connection means connecting the plurality of compressed antennas to the transmitter section and the receiver section.

In some embodiments, the communication device includes one or more diplexers to switch antennas from one band to another.

In some embodiments, the communication device includes one or more duplexers to switch antennas between the receiver section and the transmitter section.

In an embodiment where the number of bands equals four and the number of antennas equals four, the communication device is quad-band device.

In an embodiment where the number of bands equals the number of antennas all of the bands are connected to the transmitter section and the receiver section tlirough duplexers without need of diplexers.

In an embodiment wherein the antennas include a transmitter antenna and a receiver antenna for each band, all of the bands are connected to the transmitter section and the receiver section without need of duplexers and without need of diplexers.

In one embodiment, one or more of the compressed antennas includes two or more radiation elements, each element for operating in a different one of the bands, at least one of the radiation elements includes, a plurality of electrically conducting segments, each segment having a segment length, where the segments are electrically connected in series to form a radiation element for exchange of energy in one of the bands where the radiation elements have the segments arrayed in a compressed pattern situated to create isolation between the multiple bands. The foregoing and other objects, features and advantages of the invention will be apparent from the following detailed description in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 depicts a schematic view of a quad-band cellular telephone communication device with a front-end antenna section having connector, diplexer functions integrated into the antenna section.

FIG. 2 depicts a top view of an irregular compressed antemia together with a bent monopole antenna for use in the communication device of FIG. 1. FIG. 3 depicts a schematic view of a quad-band cellular telephone communication device with a front-end antenna section having connector, diplexer functions and having RF switch/diplexer functions integrated into the antenna section.

FIG. 4 depicts a top view of a one-loop, 6-legged compressed antemia, a two-loop, 6-legged compressed antemia, a one-loop irregular compressed antenna and a meander line antenna for use in the communication device of FIG. 3.

FIG. 5 is an isometric view of the one-loop, 6-legged compressed antemia, the two-loop, 6-legged compressed antenna, the one-loop irregular compressed antenna and the meander line antemia of FIG.4 mounted on a flexible substrate that dips down at one end.

FIG. 6 depicts a schematic of a quad-band cellular telephone communication device with a front-end anteima section having connector, diplexer functions, RF switch/diplexer functions and duplexer functions integrated into the antenna section.

FIG. 7 depicts an eight-layer multiple band integrated anteima front end device for use in the communication device of FIG. 6.

FIG. 8 depicts a schematic view of a tri-band cellular telephone communication device for GSM900, PCS and DCS bands with a front-end antenna section having connector, diplexer functions and RF switch/diplexer functions integrated into the antenna section.

FIG. 9 depicts a top view of a one-loop, 6-legged compressed antemia, a two-loop, 6-legged compressed anteima and a one-loop irregular compressed antenna for use in the communication device of FIG. 8.

FIG. 10 depicts a wireless communication device having a tri-band compressed antenna.

FIG. 11 depicts a schematic, cross-sectional end view of the FIG. 10 communication device. FIG. 12 depicts an isometric view of a base supporting antennas used in the communication device of FIG. 10 and FIG. 11.

FIG. 13 depicts components of the communication device of FIG. 10 including an antenna front-end and a transceiver unit.

FIG. 14 depicts a short electric dipole element antenna FIG. 15 depicts a three-dimensional representation of the fields of the short electric dipole element of FIG. 14.

FIGJ6 depicts a short loop element.

FIG. 17 depicts a three-dimensional representation of the fields of the short loop element of FIG. 16. FIG. 18 depicts a three-dimensional representation of the E_θ and H_φ fields of the short dipole element of FIG. 14 and the E_φ and H_θ fields of the short loop element of FIG. 16.

FIG. 19 depicts a two-dimensional representation of the E_θ andH_φ fields of the short dipole element of FIG. 14 and the E_φ and H_θ fields of the short loop element of FIG. 16.

FIG. 20 depicts a perspective view of two single-looped, 6-legged antenna mounted on a flexible substrate for use in a communication device.

FIG. 21 depicts a perspective view of the two single-looped, 6-legged antenna mounted on a flexible substrate of FIG.20 with the addition of two printed filters on the top of the substrate for use in a communication device.

FIG. 22 depicts a perspective view of the two single-looped, 6-legged antenna mounted on a flexible substrate of FIG. 21 with the two printed filters reduced in size and mounted on a vertical face of the substrate. FIG. 23 depicts a side view of one of the printed filters of FIG. 22 with additional detail.

FIG. 24 depicts an exploded view of a two-layer antenna having as the top layer a one-looped, irregular compressed antemia and having on the bottom layer a one-loop, six-legged compressed antenna connected to a printed filter. FIG. 25 depicts a voltage standing wave ration (VSWR) representation of the outer layer antenna of FIG. 24.

FIG.26 depicts a voltage standing wave ration (VSWR) representation inner layer antenna of FIG. 24 plus BPF.

FIG. 27 depicts a voltage standing wave ration (VSWR) representation of the isolation plot between the inner layer antenna of FIG. 24 and the outer layer antenna of FIG. 24. FIG. 28 depicts a side-view of a flip-top communication device with a cost image of the moving top.

FIG.29 is a front- view photograph of the communication device of FIG.28.

FIG. 30 is a top view of a slot anteima mounted on a substrate intended for use with the communication device of FIG. 28 and FIG. 29.

FIG. 31 is a top view of a snowflake loop antenna mounted on a substrate intended for use with the communication device of FIG. 28 and FIG. 29.

DETAILED DESCRIPTION FIG. 1 depicts a schematic view of a quad-band cellular telephone communication device 1, with a front-end antemia section 3_] having connector, diplexer functions integrated into the anteima without need of typical connector or diplexer components 17. FIG. 1 includes an irregular compressed antenna 16_rl and a bent monopole antenna 16,-2 which receive and/or transmit radio wave radiation for the telephone communication device 1. These antenna are com ected directly through antenna interfaces 18,-1 and 18,-2 to the RF switches/diplexers 15-1 and 15-2, without need for the typical connector, diplexer unit 17 that alternatively connects at connection points 10, and 10₂.

The RF switcli/diplexer 15-1 connects to duplexer 14,-1 which transmits or receives through channel TxUS CELL from the transmitter section 11 or channel

RxUS CELL to the receiver section 12. The RF switcli diplexer 15-1 connects to duplexerl4,-2 which transmits or receives tlirough channel RxGSM900 from the transmitter section 11 or channel TxGSM900 to the Receiver section 12. The RF switcli/diplexer 15-2 connects to duplexer 14,-3 which transmits or receives tlirough channel TxPCS from the transmitter Section 11 or channel RxPCS to the receiver section 12. The RF switcli/diplexer 15-2 connects to duplexer 14,-4 which transmits or receives tlirough channel Tx DCS from the transmitter section 11 or channel Rx DCS to the receiver section 12.

FIG.2 is a top view of a multiband antenna 16, formed of multiple radiation elements including a one-loop irregular compressed antenna 16,-1 with an antemia interface 18,-1 together with a bent monopole antenna 16,-2 with an antenna interface 18,-2 for use in a communication device such as that shown in FIG. 1. The radiation element formed of the one-loop irregular compressed anteima 16,-1 operates in the US Cell and GSM900 frequency bands. The radiation element formed of the bent monopole antenna 16,-2 operates in the PCS and DCS frequency bands.

FIG. 3 depicts a schematic view of the quad-band communication device 1₃ with a front-end antemia section 3₃ having connector, diplexer functions and having RF switcli diplexer functions integrated into the antenna without need of typical separate connector, diplexer section 17 (see FIG. 1) and without need of a separate RF switch, diplexer section (see FIG. 1). FIG. 3 includes four radiation elements, namely, antennas 16₃-1, 16₃-2, 16₃-3 and 16₃-4 with corresponding antemia interfaces 18₃-1, 18₃-2, 18₃-3 and 18₃-4, respectively. Antemia 16₃-1 connects for the US CELL band to duplexer 14₃-1 which transmits and receives tlirough the Tx US CELL channel from the transmitter section 11 and the Rx US CELL channel to the receiver section 12. Antenna 16₃-2 connects for the GSM900 band to duplexer 14₃-2 which transmits and receives through the Tx GSM900 channel from the transmitter section 11 and the Rx US CELL channel to the receiver section 12. Antenna 16₃-3 connects for the PCS band to duplexer 14₃-3 which transmits and receives through the Tx PCT channel from the transmitter section 11 and the Rx PCS channel to the receiver station 12. Anteima 16₃-4 connects for the DCS band to duplexer 14₃-4 which transmits and receives for the Tx DCS channel from the transmitter section 11 and the Rx DCS channel to the receiver station 12.

FIG. 4 depicts a top view of a multiband antemia 16₃ formed of multiple radiation elements including a one-loop, 6-legged compressed anteima 16₃-3 with connection lines 47₄-l, a two-loop, 6-legged compressed antemia 16₃-4 including two compressed loops 16₃-4, and 16₃-4₂ which combine into connection lines 47₄-3 , a one-loop irregular compressed antenna 16₃-1 with connection lines 47₄-2 and a meander line antenna 16₃-2 with a connection line 47₄-4 for use in the communication device of FIG. 3. FIG. 5 is an isometric view of the one-loop, 6-legged compressed antenna

16₃-3 with connection lines 47₄- 1 , a two-loop, 6-legged compressed antenna 16₃-4 including two compressed loops 16₃-4, and 16₃-4₂ which combine into connection lines 47₄-3, a one-loop irregular compressed antemia 16₃-1 with connection lines 47₄-2 and a meander line antenna 16₃-2 with a com ection line 47₄-4 of FIG. 3 mounted on a flexible substrate that dips down at one end to create new connection lines 47₅-l, 47₅-2, 47₅-3 and 47₅-4.

FIG. 6 depicts a schematic of a quad-band cellular telephone communication device 1₆ with a front-end antenna section 3₆ having connector, diplexer functions, having RF switch/diplexer functions and having duplexer functions integrated into the antenna section. FIG. 6 includes eight radiation elements, namely, eight antennas 16₆-1, 16₆-2, 16₆-3,16₆-4,16₆-5, 16₆-6, 16₆-7 and 16₆-8 with corresponding antenna interfaces 18₆-1, 18₆-2, 18₆-3,18₆-4,18₆-5, 18₆-6, 18₆-7 and 18₆-8. Antenna 16₆-1 comiects for the US CELL band through the RxUSCELL chamiel to the receiver section 12. Antennal6₆-2 connects for the US CELL band through the TxUSCELL channel the transmitter section 11.

Antennal6₆-3 comiects for the GSM900 band through the RxGSM900 channel to the receiver section 12. Antennal6₆-4 connects for the GSM900 band for the GSM900 channel to the transmitter section 11. Antennal 6₆-5 connects for the PCS band through the Rx PCS channel to the receiver section 12. Antenna 16₆-6 comiects for the PCS band through the Tx PCS channel to the transmitter section 11. Antemia 16₆-7 for the DCS band through the RxDCS channel to the receiver section 12. Antenna 16₆-8 connects for the DCS band through the TxDCS channel to the transmitter section 11.

FIG. 7 is an exploded view of an 8-layer multiband antenna 16₆ for use with the communication device of FIG. 6. The multiband antenna 16₆ includes multiple radiation elements including antennas 16₆-1, 16₆-2, .... 16₆-8 on layers 65,, 65₂, ..., 65₈, respectively. The top layer 65 , contains a compressed antenna 16₆- 1 with seven via pairs 30,-2 and 30₂-2; ...; 30,-8 and 30₂-8 and eight anteima interfaces 18₆1, 18₆2, 18₆3, ..., 18₆7 and 18₆8. The second layer 65₂ contains a compressed antenna 16₆-2 with seven via pairs 30,-2 and 30₂-2; ...; 30,-8 and 30₂-8. The bottom layer 65₈ contains a compressed antenna 16₆-8 with one via pair 30,-8 and 30₂-8. Each layer connects to the one above it tlirough the via pairs 30,-2 and 30₂-2; ...; 30,-8 and 30₂-8 up to the top layer 65, and the via pairs 30,-2 and 30₂-2; ...; 30,-8 together with the connection lines for antemia 16₆-1 connect to the interfaces 18₆1, 18₆2, 18₆3, ..., 18₆8 for connection to the transmitter section 11 and receiver section of FIG. 6. FIG. 8 depicts a schematic view of a tri-band cellular telephone communication device 1₈ for GSM900, PCS and DCS bands with a front-end antemia section 3₈ having connector, diplexer functions and having RF Switch/Diplexer integrated into the antemia functions without need of a separate connector, diplexer section 17 (see FIG. 1) or separate RF Switchs/Diplexers (see FIG. 1 ). FIG. 8 includes three radiation elements, namely, three antennas 16₈- 1 , 16₈-

2 and 16₈-3 , with corresponding antenna interfaces 18₈-l , 18₈-2 and 18₈-3. Antenna 16₈-1 connects for the GSM900 band to the Duplexer 14₈-1 which transmits and receives through the Tx GSM900 channel from the Transmitter section 11 and the Rx PCS channel to the Receiver section section 12. Antenna 16₈-2 connects for the PCS band to Duplexer 14₈-2 which transmits and receives through the Tx PCS channel from the Transmitter section 11 and the Rx GSM900 channel to the Receiver section section 12. Antenna 16₈-3 connects for the DCS band to Duplexer

14_g-3 which transmits and receives tlirough the Tx DCS channel from the Transmitter section 11 and the Rx DCS channel to the Receiver section Station 12. FIG. 9 is a top view of a multiband antenna 16₈ for use with the communication device of FIG. 8. The antemia 16₈ is formed of multiple radiation elements including a single-loop irregular compressed antenna 16₈- 1 connecting at one end to connector pad 23-2 and connecting at the other end to connector pad 23- 3, a two-looped, 6-legged compressed antemia 16₈-3 combining to connect at one end to connector pad 23-1 and connect at the other end to connector pad 23-3, and a single-looped, 5-legged antenna 16₈-2 connecting at one end to connecting pad 23-3 and connecting at the the other end to comiecting pad 23-4. The connecting pads are of the type that connect to the circuit board 6 of FIG. 11 using a connector with spring tangs.

In FIG. 10, communication device 1 ,₀ is a cell phone, pager or other similar communication device that can be used in close proximity to people. The communication device 1 ,₀ includes an antenna area 2 allocated for an antenna 16₈ which receives and/or transmits radio wave radiation for the communication device 1₁₀. In FIG. 10, the antenna area 2 has a width D_w and a height D_H. A section line 2'~2" extends from top to bottom of the communication device 1,₀. Typically, the antenna 16₈ is affixed to the inside of the case 1₁₀' of communication device 1 ,₀ by a pressure sensitive adhesive, injection molding, insert molding or any other convenient manner of attachment. The case 1,₀' may be flat or curved so that antennas in some embodiments lie in one or more planes where those planes take the shape of the case 1_]0' which can be flat or curved.

In FIGJO, the antenna 16₈ is a multi-loop antenna like that shown in FIG. 9. The loops 16₈-3₂ and 16₈-3, are com ected in common by connection pads 23-1 and 23 -3. The connection pads 23-1 and 23-3 are the termination points for antenna

16₈-3. Typically one of the termination points (23 - 1 ) is the drive point and the other termination point (23-3) is the common or ground point. The loops 16₈-3 , and 16_g- 3₂ generally lie in the XY-plane and have magnetic current in the Z-axis direction normal to the XY-plane. In FIG. 9 and FIG. 10, antemia 16₈-2 (4_T2) has a plurality of electrically conducting radiation segments 4_T2-1, 4_T2-2, 4_T2-3, ..., 4_τ2-n, ..., 4_T2-N each having a segment length. The segments 4_T2-1, 4_T2-2, 4_T2-3, ..., 4_T2-?7, ..., 4_T2-Nare connected in series to form a loop electrically comiected between the first and second conductor pads 23-3 and 23-4. The loop 4_T2 has an electrical length, A_{l T2}, that is proportional to the sum of segment lengths for each of the radiation segments 4_T2- 1 ,

4_T2-2, 4_T2-3, ..., 4_T2-τ., ..., 4_T2-Nso as to facilitate an exchange of energy at radiation frequencies for anteima 4_T2. Similarly, the loop 16₈-1 (4_T1) has an electrical length, A. _τ,, that is proportional to the sum of segment lengths for each of the radiation segments so as to facilitate an exchange of energy at radiation frequencies for antemia 4_T1.

The term "segment" means any portion of a straight or curved line. Multiple segments are connected together end to end to form a loop. The interconnection of segments can appear discontinuous, for example where two straight-line segments form an angle less than 180 degrees, or can appear continuous, for example, where curved segments connect with a smooth continuous transition without a perceptible intersection. A continuous loop or continuous portions of a loop, where segment intersections are not apparent, can be arbitrarily partitioned into any number of short continuous segments with arbitrary locations of the intersections. The number of segments for a compressed loop is not particularly important. The important characteristic of a compressed loop is that the loop trace is one that has many turns that have the effect of lengthening the loop trace (electrical length of the loop) while reducing the enclosed area of the loop. A loop with such characteristics is defined to be a compressed loop having a compressed pattern. A compressed loop is compared with an equivalent circular loop formed with a circumference equal to the sum of all the lengths of the segments of the compressed loop. The enclosed area of the compressed loop is substantially less than the enclosed area of the equivalent circular loop.

In FIG. 10, each of the loops 4_T, and 4_T2 is formed of straight-line segments arrayed in irregular compressed patterns and connected electrically in series to form a loop antenna. The straight-line segments of the anteima 4_Ω. for example, fit within the antenna area 2, which has been allocated for an antenna in the communication device 1 ,₀ of FIG. 10. The antenna 4_T2 has an actual enclosed area,

A_area, that can be represented by an imaginary circle of radius R, so that A_area = π(R,)² and the imaginary circle has a circumference of π(2R,). The antemia 4_T2 has an electrical length, A_{l T2} which if stretched into a circle would have a circumference of π(2R₂) where π(2R₂) is significantly longer than the circumference π(2R,) of the imaginary circle representing the area enclosed by antenna 4_T2.

In FIG. 10, each of the loops 4_T, and 4_T2 is formed of straight-line segments arrayed in multiple divergent directions not parallel to the XY orthogonal coordinate system so as to provide a long antenna electrical length while permitting the overall outside dimensions of the loops to fit within the antenna area 2 of the communication device 1,₀. The FIG. 10, anteima elements 4_T] and 4_T2, are used for communication in frequency bands having, within the bands, nominal frequencies f, and f₂ with wavelengths, λ_τ, and λ_T2, for one or more of the respective resonant frequencies of interest. In general, the frequencies f, and f₂ are not harmonically related. The wavelengths, λ_τ, and λ_T2, are such that, for efficient antemia design, the electrical lengths, A_lT, and A_lT2, cam ot be made small with respect to λ_τl and λ_T2. For this reason, it cannot be assumed that the simple analytical models used to describe loop antennas and electric dipole antennas apply without limitation. Rather, the analytical models are mathematically complex and not easily describable. In FIG. 11, the communication device 1,₀ of FIG. 10 is shown in a schematic, cross-sectional, end view taken along the section line 2'-2" of FIG. 1. In FIG. 11 , a circuit board 6 includes, by way of example, an outer conducting layer 6-1, internal insulating layers 6-2,, 6-2₂, 6-2₃, internal conducting layers 6-4, and 6-4₂ and another outer conducting layer 6-3. Typically, the layer 6-4, is a ground plane and the layer 6-4₂ is a power supply plane. The printed circuit board 6 supports the electronic components associated with the communication device 1₁₀ including a display 7 and miscellaneous components 8-1, 8-2, 8-3 and 8-4 which are shown as typical. Communication device 1₁₀ also includes a battery 9. The antenna assembly 5 includes in one embodiment, a connector with tangs for connecting to antemia 16₈ of FIG. 10 or alternatively a support 25 as shown in FIG.

11. In FIG 10, a conductive layer 5-2 that forms a loop antenna is offset from the printed circuit board 6 by a gap which tends to reduce coupling between the antemia and the printed circuit board 6. In one embodiment, the offset of the antenna, H_A, above the board 6 is 6.92mm and the offset of the antenna from the top of a can component mounted on board 6, such as component 8-4, is 4.83mm. Typical offsets of the antenna 4 from the circuit board 6 are less than 10mm and desirably less than approximately 5mm. The ability of the compressed antenna to operate well with little or no offset (less than 20mm) from the circuit board 6 is a feature of the antennas that make them attractive for use in hand-held and other small communication devices.

The assembly 5 is typically constructed using well-known printed circuit materials and processes. For example, the materials include flexible laminates, polyimide flexible laminates, polyimide ridgidized substrates, polyester flexible substrates, polyester ridgidized substrates and plastics, glasses, woven glass laminates such as FR4, other laminates and other dielectrics in general. For example, the processes include printing or silk- screening of a metal onto a dielectric substrate, silk-screening onto the case of a mobile telephone or other commination device, metal deposition onto a dielectric substrate, stamping from a metal sheet, injection molding into the plastic of a mobile telephone case or other communication device, and insert molding into the plastic of a mobile telephone case or other communication device, and other layer and sheet formations of all types.

The antennas of FIG. 10 and FIG. 11, as described in many different embodiments includes a compressed antenna that has small area so as to fit within the antenna area 2 of communication device 1,₀. The antenna operates with loop antemia properties, has low SAR and exhibits good performance in transmitting and receiving signals.

FIG. 12 depicts a plastic base 25 which fits onto the communication device 1,₀ of FIGS. 10 and 11. A single-loop, irregular compressed antenna 16,₂-2 is mounted on the bottom of the base 25 and is comiected to circuit board 6-3 of FIG. 11 by connection point 35₁₂-2. A single-looped, six-sided compressed antemia 16, ₂- 1 is mounted on the top of base 25 and is connected to circuit board 6-3 of FIG. 11 by connection point 35, ₂-l . A single-looped, five-sided compressed antemia 16₁₂-3 is mounted on the top of the base 25 and is connected to circuit board 6-3 of FIG. 11 by connection point 35,₂-3.

FIG. 13 depicts an antenna front-end 4 combined with a transceiver unit (TU) 91 on the communication device 1 of FIG. 10. FIG. 14 depicts a short dipole element 61 along the Z axis normal to the

XY-plane of antemia. The short dipole element is useful in explaining properties of antennas.

FIG. 15 depicts a three-dimensional representation of the fields of the short dipole element of FIG. 14. As discussed above, the equations of electric and magnetic components of the electric dipole at the far field axe given as:

E,. = 0

;60^[/]sin-? L

E_D

j[I]smθ L ^{Mφ ~} ϊr λ

Examining the E_θ and H_φ components in the far field, it can be seen that E_θ and H_φ are in time phase (with respect to each other) in the far field, and that the field patterns of both are proportional to sin(θ) but independent of φ. The space patterns of those fields are a figure of revolution and doughnut-shaped in three dimensions (see FIG. 18) figure-8 shaped in two dimensions (see FIG. 19).

FIG. 18 depicts a short loop element 81 lying in the XY-plane. A magnetic dipole for the loop element 81 conducts an electric current I that causes a magnetic current (I_m) in the Z axis direction normal to the XY-plane of the magnetic dipole. The analysis of the far field pattern of a magnetic dipole of FIG. 16 is similar to the analysis of the far field pattern of the electric dipole of FIG. 14 . The difference is that the electric current /is replaced by a magnetic current I_m a d the electric field is replaced by a magnetic field.

FIG. 17 depicts a three-dimensional representation of the fields of the short loop element of FIG. 16. The fields of the short magnetic dipole are the same as the fields of a short electric dipole with the E and H fields and / and I_m currents interchanged as follows:

Considering the equation of the far field pattern for the magnetic dipole, both H_θ and E_φ are proportional to sin(θ) but independent of φ. Consequently, the far field pattern of the H_θ and E_φ components of a magnetic dipole are doughnut- shaped in three dimensions (see FIG. 18) and figure- 8 circular in cross section (see FIG. 19).

FIG. 18 depicts a three-dimensional representation of the E_θ and H_φ fields of the short dipole element of FIG. 14 and the E_φ and H_θ fields of the short loop element of FIG. 16. FIG. 19 depicts a two-dimensional representation of the E_θ and H_φ fields of the short dipole element of FIG. 14 and the E_φ and H_θ fields of the short loop element of FIG. 16.

In FIG. 14 through FIG. 19, properties of small elements were described to depict the nature of electric dipole operation and magnetic loop operation. Antennas that have properties that like those of the small magnetic loop of FIG. 16 are classified as "loop" antennas or as having loop antenna characteristics. While an extension of the mathematical derivation described in connection with FIG. 14 through FIG. 19 to the more complex compressed loops and antennas of the present application is not easily done, the actual performance of those compressed loops and antennas demonstrate loop antenna characteristics including good radiation properties and low SAR values.

FIG. 20 depicts an isometric view of a flexible substrate 16₂₀ for use in a communication device. Mounted on the top of the flexible substrate are two single- looped, 6-legged antennas 29,₄ and 28,₄. The flexible substrate contains several lengths which curve down 65₂₀ including a flat horizontal vertical 31-1, a downward curve 31-2, a flat vertical 31-3, an upward curve 31-4, and a flat horizontal 31-5. The flexible substrate also contains an edge 32.

FIG. 21 depicts an isometric view of a flexible substrate 16₂, for use in a communication device. Mounted on top of the flexible substrate are two single- looped, 6-legged antennas 29,₅ and 28,₅. The flexible substrate contains a downward curve 65_2]. Antenna 28, ₅ comiects at connection points 34-1 and 34-2 to a printed filter 34. The printed isolation filter includes connection points 34-3, 34-4, 34-5 and 34-6. The antenna passes through the printed filter and slopes down the flexible substrate curve 65₂₁.

FIG. 22 depicts an isometric view of a flexible substrate 16₂₂ for use in a communication device. Mounted on top of the flexible substrate are two single- looped, 6-legged antennas 29, ₆ and 28, ₆. The flexible substrate contains a downward curve 65₂₂. Antenna 28, ₆ comiects at connection point 36 and curves down the flexible substrate 16₂₂ to a compacted printed filter 34 which contains connection points 36-1, 36-2, 36-4- and 36-5. The smaller, printed isolation filter 34 is placed on the vertical wall of the flexible substrate slope 65₂₂. Antemia 29,₆ connects at connection point 35 and curves down the flexible substrate 16₂₂ to a compacted printed filter 33 which contains connection points 35-1, 35-2, 35-4- and 35-5. The smaller, printed isolation filter 33 is placed on the vertical wall of the flexible substrate slope 65₂₂. FIG. 23 depicts a side view of one of the printed filters of FIG. 22 with additional detail. The printed filter 34 contains a conductor 66-1 with a length of approximately 33.06mm and multiple parallel conductors 66-2 with antemia connection points at 23₂₃-l and 23₂₃-2. The width of the printed filter is approximately 9.25 mm. FIG. 24 depicts an exploded view of a two-layer antenna 16₂₄ having as the top layer 65₂₄-l a one-loop, irregular compressed antenna 16₂₄-1 and having on the bottom layer 65₂₄-2 a one-loop, six-legged compressed antenna 16₂₄-2 connected to a printed filter 16₂₄-3. The printed filter extends over the curved portion 31₂₄ of the substrate layer 65₂₄-2. One end of the one-loop, six-legged compressed antemia 16₂₄-2 connects to the filter 66-1 of the printed filter 16₂₄-3 and the other end connects to the capacitively coupled section 66-2 at connection point 23₂₃-2. Connection point 23₂₃-l is at the other end of section 66-2.

FIG. 25 depicts a voltage standing wave ration (VSWR) representation of the antenna 16₂₄-1 of FIG. 24. FIG.26 depicts a voltage standing wave ration (VSWR) representation inner layer antenna 16₂₄-2 and filter 16₂₄-3 of FIG. 24. FIG. 27 depicts a representation of the isolation between the antennas of FIG. 24.

FIG. 28 depicts a side-view of a communication device lwith a flip-top 1 , and a ghost image of the flip-top 1', . The communication device contains a transceiver unit 91 with an attached anteima on substrate 65₃, mounted on the X'-Z' axis (see FIG. 31). The flip-top 1, contains an antenna on substrate 65₃₀ mounted on the XZ axis (see FIG. 30), with the X plane lying on the bottom of the flip-top.

FIG. 29 depicts a representation of the front view of the communication device 1 of FIG. 28. FIG. 30 is a top view of a slot antenna 16₃₀ mounted on a substrate 65₃₀, having an X- Y-Z coordinate axis system as mounted in the communication device ofFIG. 28 and FIG. 29.

FIG. 31 is a top view of a snowflake loop antenna 16₃, mounted on a substrate 65₃₁, having an X'-Y'-Z' axis coordinate system as mounted in the communication device of FIG. 28 and FIG. 29.

The loop antennas described in the various anteima embodiments operate in cellular frequencies of the world including those of North America, South America, Europe, Asia Australia. The cellular frequencies are used when the communication device is a mobile phone, PDA, portable computer, telemetering equipment or any other wireless device. The loop antennas described in the various antemia embodiments operate to transmit and/or receive in mobile telephone frequency bands, for example, anywhere from 800 MHz to 2500 MHz.

While many different embodiments of compressed antennas have been described, the different features and variations of each embodiment may be readily transferred to other embodiments. A feature on one loop of an antemia may be transferred to another loop of the antenna. The interaction of multiple loops in a multi-loop antenna fosters the interchangeability of features from loop to loop. While the invention has been particularly shown and described with reference to preferred embodiments thereof it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention.

Claims

1. A communication device operating for exchanging energy in a plurality of bands of radiation frequencies, comprising, a plurality of compressed antennas, each antenna for operating with one or more of said bands of radiation frequencies, a transmitter section for processing transmitter signals, a receiver section for processing receiver signals, connection means connecting to said plurality of compressed antennas to said transmitter section and said receiver section.

2. The communication device of Claim 1 wherein said connection means includes one or more diplexers to switch antennas from one band to another.

3. The communication device of Claim 1 wherein said connection means includes one or more duplexers to switch antennas between said receiver section and said transmitter section.

4. The communication device of Claim 1 having a number of bands and having a number of anteimas and wherein said connection means connects all of said bands to said transmitter section and said receiver section.

5. The communication device of Claim 4 wherein said number of bands equals said number of antennas whereby said comiection means connects all of said bands to said transmitter section and said receiver section without need of a diplexer.

6. The communication device of Claim 5 wherein said number of bands equals four and said number of antennas equals four whereby said commmiication device is quad-band device.

7. The communication device of Claim 1 having a number of bands and having a number of antennas, wherein said number of bands equals said number of anteimas and wherein said connection means comiects all of said bands to said transmitter section and said receiver section through duplexers without need of diplexers.

8. The communication device of Claim 1 having a number of bands and having a number of antennas, wherein said antennas include a transmitter antemia and a receiver antemia for each band and wherein said connection means comiects all of said bands to said transmitter section and said receiver section without need of duplexers and without need of diplexers.

9. The communication device of Claim 1 wherein said plurality of bands includes two bands and said communication device is a dual-band device.

10. The communication device of Claim 1 wherein said plurality of bands includes three bands and said communication device is a tri-band device.

11. The communication device of Claim 10 wherein said band sets include GSM 900 band frequencies, PCS band frequencies and DCS band frequencies.

12. The communication device of Claim 1 wherein said plurality of bands includes four bands and said communication device is a quad-band device.

13. The commmiication device of Claim 12 wherein said bands include US cell band frequencies, GSM 900 band frequencies, PCS band frequencies and DCS band frequencies.

14. The communication device of Claim 1 wherein one or more of said compressed antennas includes, two or more radiation elements, each element for operating in one or more of said bands and where at least one of said radiation elements includes, a plurality of electrically conducting segments, each segment having a segment length, where the segments are electrically connected in series to form a radiation element for exchange of energy in one or more of said bands, said one of said radiation elements having said segments arrayed in a compressed pattern that creates isolation between said bands.

15. The communication device of Claim 14 wherein radiation elements are nested where an area enclosed by one of the radiation elements is within an area enclosed by another of the radiation elements.

16. The communication device of Claim 14 wherein radiation elements are nested in a single plane where an area enclosed by one of the radiation elements is within an area enclosed by another of the radiation elements.

17. The communication device of Claim 16 wherein said plane is flat.

18. The communication device of Claim 16 wherein said plane is curved.

19. The communication device of Claim 14 wherein radiation elements are nested on the same layer supported by a dielectric substrate where an area enclosed by one of the radiation elements is within an area enclosed by another of the radiation elements.

20. The communication device of Claim 14 wherein radiation elements are on different layers supported by a dielectric substrate.

21. The communication device of Claim 14 wherein a majority of said segments are straight and arrayed in multiple divergent directions not parallel to an orthogonal coordinate system so as to provide a long antenna electrical length while permitting an overall outside dimension of said radiation element to fit within an antenna area of said communication device.

22. The communication device of Claim 14 wherein said radiation element has an irregular shape and wherein said segments are arrayed in an irregular compressed pattern.

23. The communication device of Claim 14 wherein said segments of one or more of the radiation elements are situated on a flexible dielectric substrate.

24. The communication device of Claim 14 wherein said radiation elements transmit and receive radiation.

25. The communication device of Claim 14 wherein one or more of said radiation elements transmit and receive in the US PCS band operating from 1850 MHz to 1990 MHz.

26. The communication device of Claim 14 wherein one or more of said radiation elements transmit and receive in a European DCS band operating from 1710 MHz to 1880MHz.

27. The communication device of Claim 14 wherein one or more of said - radiation elements transmit and receive in a European GSM band operating from 880 MHz to 960 MHz.

28. The communication device of Claim 14 wherein one or more of said radiation elements transmit and receive in a US cellular band operating from 829

MHz to 896 MHz.

29. The communication device of Claim 14 wherein one or more of said radiation elements transmit and receive in mobile telephone frequency bands anywhere from 800 MHz to 2500 MHz.

30. The communication device of Claim 14 wherein one or more of said radiation elements is on one layer mounted on a dielectric material and one or more other ones of said radiation elements is on a different layer mounted on said dielectric material.

31. The communication device of Claim 14 where radiation elements are nested to create a dual-band, band-pass antenna with good rej ection between bands .

32. The communication device of Claim 14 where radiation elements are nested to create a tri-band, band-pass antenna with good rejection between bands.

33. The communication device of Claim 14 where radiation elements are nested to create a quad-band, band-pass antenna with good rejection between bands.

34. The communication device of Claim 14 where radiation elements are located on any one of a plurality of layers.

35. The communication device of Claim 14 where one or more of the radiation elements are nested and comiected to form a closed radiation element.

36. The communication device of Claim 35 where one or more of said closed radiation elements are floating.

37. The commmiication device of Claim 14 wherein said antenna operates in the any combination of bands from a group of bands in the range from 3 MHz to300 Ghz.

8. The communication device of Claim 1 including, a case for housing the communication device, a circuit board internal to said case for supporting electrical components including said compressed anteimas, said transmitter section, said receiver section and said connection means.