US3264647A - Antenna support enclosing slug-tuned inductor which is adjustable through a socket in which antenna is mounted - Google Patents

Description

Aug. 2, 1966 A. c. NUTTLE 3,264,547

ANTENNA SUPPORT ENCLOSING SLUG-TUNED INDUCTOR WHICH IS ADJUSTABLE THROUGH A SOCKET IN WHICH ANTENNA IS MOUNTED Filed June 29, 1964 flrzdrew 6. N 245170 United States Patent 3,264,647 ANTENNA SUPPORT ENCLUSING SLUG-TUNED INDUCTOR WHHJH IS ADJUSTABLE THRQUGH A SOCKET IN WHICH ANTENNA 1S MOUNTED Andrew C. Nuttle, Gain Electronics, Inc., 138 Lincoln St., Manchester, NH. Filed June 29, 1964, Ser. No. 378,787 11 Claims. ((Il. 343-745) The field of the present invention is that of antenna mounts and couplers or tuners and the invention relates more particularly to a combined mount and tuner of especially compact and efiicient arrangement.

Objects of the invention are to provide an antenna mount which integrally incorporates an adjustable antenna coupler, so that electromagnetic wave energy .can be efficiently coupled to the antenna and so that the resonant characteristics of the antenna can be easily adjusted to complement the characteristics of the environment in which it is to be used. Further objects are to provide a combination antenna mount and tuner which can be easily installed especially on cars or other conveyances, which presents a functionally attractive appearance, which is mechanically rugged, which exhibits stable electric characteristics, regardless of weather, wear and vibration; the electrical characteristics of which can be quickly and easily adjusted with a minimum of tools and with the antenna in place; in which the electrical components are protected from the elements for exterior, such as automotive, use; which is of relatively simple and inexpensive construction and which is of compact and unobtrusive appearance.

The substance of the invention may be characterized as contemplating the incorporation of an antenna tuner into an antenna mount while maintaining a very compact and uncluttered construction and appearance by employing a single aperture into the mount for both receiving the antenna rod and for providing access to the tuning adjustment. In the preferred embodiment the tuning adjustment is obtained by adjustably positioning a tuning slug relative to a coil. The slug is mounted on a threaded spindle extending into the same aperture which receives the antenna rod. Preferably there are means for coupling rotational motion of the rod to the spindle so that tuning adjustments may be made by rotating the antenna rod.

In one particular aspect the invention contemplates an antenna tuning mount involving a coaxial connector and a hollow cylindrical coil form attached to the connector coaxially therewith. A coil is wound around the form and a rigid conforming envelope of insulating material supports the connector, the coil form and a coaxial sleeve is aligned relationship. A tuning slug fits within the form and a threaded spindle is provided for mounting the slug on the sleeve for movement axially of said coil.

These and other objects and novel characteristics of the invention will appear from the following description of a preferred embodiment thereof by way of example.

The description refers to a drawing in which:

FIG. 1 is a side view of a complete antenna mount and tuner;

FIG. 2 is an exploded view, partially in section, of components of the mount;

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FIG. 3 is a vertical sectional view of the mount taken on the line 3-3 of FIG. 5;

FIG. 4 is a schematic circuit diagram of the tuner; and

FIG. 5 is a diagram in plan, for the purpose of showing the section line 33.

The mount includes a conventional coaxial connection 12 which involves an outer, internally threaded barrel 1-4 and a center pin 16 which is mounted coaxially therewith on an insulating disc 17. On top of this connector is placed an insulating plastic coil form 20. This coil form includes a broad annular groove 22 for a coil 32, and longitudinal slots 24 for the leads to the coil. These slots are filled with plastic after wiring and assembly, as subsequently explained, and that slot which would be cut through by the section plane at the right side of FIG. 3 is so shown, filled up.

A metallic cap element 26 having a skirt portion 27, fits snugly over the upper end of the coil form 20 and an extension element 28, also metallic, is coaxially mounted at the closed end of the cap element 26 by means of matching threads. It will be convenient to refer to the two elements 26 and 28 as a sleeve; this sleeve has two parts mainly because it has considerably different diameters and can be more conveniently and economically so manufactured in two parts. The central bore of the upper part 28 of the sleeve is internally threaded to receive the screw-threaded mounting spindle 29 of a brass or powdered iron tuning slug 30. The parts are so dimensioned that when the sleeve is placed over the coil form 20, the tuning slug 30 is disposed within the central bore 21 of the coil form 20. The lower end of antenna rod 50 extends into central bore of part 28, coaxially with the screw 29.

According to the presently preferred practice of the invention, an antenna tuning coil 32 is wound in the annular groove 22 and is connected with fixed ceramic capacitors 34 and 36 so as to be resonant in the band of frequencies in which the antenna is to be used. The connections are conventional and the circuit employed for this purpose is shown in FIG 4. Appropriate leads from the coil 32 are brought out through the longitudinal slots 24 and the capacitors 34 and 36 are soldered to one of these leads. Capacitor 36 is soldered to the barrel 14 at 27, FIG. 2, and capacitor 34 is soldered to a lead 35 which as indicated in FIG. 3 extends to the central pin 16. The connection of the coil to the antenna proper is made by means of a screw 38 threaded into the skirt portion 27 of the cap element 26 as shown in FIG. 3.

After the circuit is wired and the sleeve 26, 28 assembled with the coil form 20, an encapsulating envelope and base 40 of an insulating plastic is molded around the connector 12, the coil form 20, the capacitors 34 and 36 and the lower portion of the sleeve. The plastic flows into the annular groove 22 and around the coil 32 through the longitudinal slots 24, but is kept from filling the central bore 21 of the coil form 20 by the tight fit of the skirt 27 around the coil form at its upper end.

It will be understood that the inside threaded barrel 14 is screwed to a conventional fitting and that the base 40 will contact a supporting surface. The mode of fastening the present mount to a support is not part of the present invention and can be accomplished in a suitable manner.

The sleeve includes at its upper end means for mounting an antenna rod. The upper end of the sleeve is threaded at 42 and includes a conical recess 44 (FIG. 2) opening into its central bore. A nut 46, similar to a gland nut, fits over these threads and contains a deformable ferrule 48. The lower end of an antenna rod 50, inserted into the sleeve through the nut 46 and the ferrule 48, can be rigidly held in position by tightening the nut 46thereby clamping the ferrule 48 tightly around the rod and securely holding it in position. This clamping action also provides an excellent seal against dirt and the effects of the elements.

Preferably the lower end of the antenna rod 50 is provided with a blade-like extension 52 and the upper end of the tuning slug spindle 29 is provided with a corresponding screw-head slot 54 so that the antenna rod 50 and the spindle 29 can be engaged for transmitting rotational motion. In this way the axial position of the tuning slug 30 and hence the inductance of the coil 32 can be easily adjusted by rotation of the antenna itself so that the effective resonant frequency of the antenna and tuner can be adjusted over a useful band of frequencies and so that compensation can be made for the characteristics of the antenna in relation to the environment in which it is to be operated.

Situations may exist when it is more convenient to remove the antenna from the mount, turn the threaded spindle 29 with a screwdriver inserted in place of the antenna, and remount the antenna. Also, even though subsequent adjustments can be made by rotating the antenna while it is in the mount, preliminary adjustment may be made by a screwdriver before the antenna is mounted.

In all of these situations, whether the screw is turned by the antenna or by a separate tool, access for adjust ment of the slug is provided by the axial bore which is adapted to receive the antenna. Thus, provision of an additional opening into the mount for adjustment of the slug is rendered unnecessary.

The slot 54 in the top of the screw is only one example of a shaping of the top so that it can be engaged to rotate the screw. Thus the top of the screw might carry an upstanding blade, and either the antenna rod or a tool might have a corresponding slot. The general thought as to the upper end of the screw is that it shall have preferably small lengthwise extending areas non-concentric with the screw axis, so that it can be engaged and rotated. In the preferred form shown these areas are the side walls of the slot 54.

As can be seen from FIG. 1, the complete mount is quite compact and exhibits a smooth and pleasing appearance. The simple internal arrangement provides stability of electrical characteristics, and, since only one, tightly sealed aperture is necessary, the electrical components are well protected.

While a particular embodiment has been shown by way of illustration it should be understood that the invention includes all modifications and equivalents falling within the scope of the appended claims.

I claim:

1. An antenna tuning mount comprising:

a sleeve having a bore to receive an antenna rod;

means for securing the rod in said bore;

a variable inductance coil in the mount in circuit with the sleeve;

a tuning slug; and

a screw for moving the slug axially of the coil, said screw being coaxial with said bore with the head of the screw accessible therethrough.

2. An antenna tuning mount according to claim 1 in which the screw has at its upper end lengthwise extending areas non-concentric with the screw axis and adapted for engagement to turn the screw.

3. An antenna tuning mount according to claim 1 ineluding,

an envelope of insulating plastic surrounding the lower part of the sleeve and extending within the sleeve around the coil.

4. Antenna tuning mount according to claim 1 including,

a capacitor in circuit with the inductance coil; and

an envelope of insulating plastic surrounding the lower part of the sleeve, the coil and the capacitor.

5. An antenna tuning mount comprising:

a hollow cylindrical coil form;

a coil wound around said form;

means for connecting one end of said coil to radio frequency energy;

a tuning slug fitting within said form;

a screw means for mounting said slug relative to said form for movement axially of said coil;

an insulating envelope enclosing said coil and form;

and

mean-s for releasably mounting an antenna rod coaxially with said screw means whereby access for the adjustment of said slug can be obtained through the antenna mounting means.

6. An antenna tuning mount according to claim 5, further comprising means for coupling rotational motion of said antenna rod to said screw means for adjustment of said slug.

7. An antenna tuning mount comprising:

a hollow cylindrical coil form;

a coil wound around said form;

means for connecting one end of said coil to radio frequency energy;

a tuning slug fitting within said form;

a hollow sleeve coaxial with said form;

screw means mounting said slug on said sleeve movement axially of said coil;

an insulating envelope surrounding said form, said coil and the end of said sleeve nearest said slug; and means for releasably mounting an antenna rod in the other end of said sleeve;

said screw means being accessible through the sleeve upon removal of said antenna rod.

8. An antenna tuning mount comprising:

a hollow cylindrical coil form;

a metallic sleeve including a portion fitting around a portion of said coil form;

a coil wound around said coil form and connected at one end to said sleeve;

means for connecting the other end of said coil to radio frequency energy; a tuning slug fitting within said form;

screw means mounting said slug on said sleeve for movement axially of said coil;

means for releasably mounting an antenna rod coaxially on said sleeve; and

means for coupling rotational movement of said antenna rod to said screw means for adjustment of said slug.

9. An antenna tuning mount comprising:

a coaxial connector;

a helical coil coaxial with said connector;

a tuning slug for said coil;

screw means for mounting said slug which permits adjustment of the slug axially of the coil;

an antenna rod;

means for coupling rotational movements of said rod to said screw means; and

means for releasably clamping said antenna rod coaxially with said coil. 10. An antenna tuning mount according to claim 9 including an externally rounded, rigid, conforming envelope of insulating material enclosing said connector and said coil.

11. An antenna tuning mount comprising:

a coaxial connector;

for

a hollow cylindrical coil form attached to said connector coaxially therewith;

a coil wound around said form;

an elongate sleeve coaxial with said form;

a rigid conforming envelope of insulating material surrounding said connector, said coil form and the lower part of said sleeve;

a tuning slug fitting within said form;

screw means for mounting said slug on said sleeve for movement axially of said coil;

6 an antenna rod; means for coupling rotational movement of said rod to said screw means; and means for releasably clamping the antenna rod within said sleeve.

No references cited.

HERMAN KARL SAALBACH, Primary Examiner.

M. NUSSBAUM, Assistant Examiner.

Claims (1)

1. AN ANTENNA TUNING MOUNT COMPRISING: A SLEEVE HAVING A BORE TO RECEIVE AN ANTENNA ROD; MEANS FOR SECURING THE ROD IN SAID BORE; A VARIABLE INDUCTANCE COIL IN THE MOUNT IN CIRCUIT WITH THE SLEEVE; A TUNING SLUG; AND A SCREW FOR MOVING THE SLUG AXIALLY OF THE COIL, SAID SCREW BEING COAXIAL WITH SAID BORE WITH THE HEAD OF THE SCREW ACCESSIBLE THERETHROUGH.

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