Antenna system with output means in parallel with resonating means

Nov. 27, 1962 _{R A}

ANTENNA SYSTEM WITH OUTPUT MEANS Filed March 16, 1956 davis 3,066,293

IN PARALLEL WITH RESONATING MEANS

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Nov. 27, 1962 r. a. _DAV|S 3,066,293

SYSTEM WITH OUTPUT «Κ TH PARALLEL WITH RESONATING MEANS Filed March 16, 1956

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INVENTOR.

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HIS ATTORNEY

United States Patent Office

3,063,293

Patented Nov. 27, 1962

3,066,293

ANTENNA SYSTEM WITH OUTPUT MEANS IN PARALLEL WITH RESONATING MEANS

Ross A. Davis, Los Angeles, Calif.

(235 Sunridge St., Playa del Rey, Calif.) Filed Mar. 16, 1956, Ser. No. 571,985

Claims. (Ci. 343—767)

This invention is directed to an improvement in antennas for the transmission and reception of electro-magnetic waves and, more particularly, to antennas using conductive portions of fixed or mobile structures as parts of the antenna or antenna system.

Numerous efforts have been made to use conductive structures having other functions as antennas for the transmission or reception of electro-magnetic waves. Earlier efforts along these lines are described and claimed in copending patent applications, Serial Nos. 487,535, now Patent No. 2,923,813, and 522,777, now Patent No. 2,971,191, filed in behalf of the present inventor. While the antennas and antenna systems described in the foregoing patent applications perform quite satisfactorily, it was deemed desirable by the inventor to proceed in his efforts to optimize the performance of such antennas incorporated in and utilizing portions of conductive structures.

Therefore, it is an object of this invention to provide an improved antenna system for use in and utilizing at least a portion of a conductive structure such as an automobile, airplane, or guided missile or any desired stationary or mobile structure.

It is a further object of this invention to provide an antenna system associated with a conductive mass or body in which maximum isolation and shielding from extraneous noise fields is assured while maximum direct coupling is maintained with the mass.

A still further object of this invention is to provide means for obtaining from a conductive mass or body electro-magnetic signals of maximum amplitude and at the same time affording the low impedance and tight coupling characteristics necessary to assuring optimum transfer of energy to and from the conductive mass or body to associated transmitting or receiving apparatus and to assure ease of tracking of such apparatus over a desired band of signal frequencies.

According to the present invention a relatively high impedance portion of a metallic structure bounded immediately by a low impedance edge portion is shunted by an element having sufficient capacitance to cause parallel resonance with the conductive edge portion in the band of frequencies in which it is intended that the antenna be operative. The voltage appearing across the resonating condenser may be used to drive a voltage transforming harness of the type described in the copending application, Serial No. 487,535, filed by this inventor on February 11, 1955.. The harness may be series resonated as described in the copending patent application, Serial No. 522,777, filed by this inventor on July 18, 1955. Inductively tuned elements may be inserted in both the parallel capacitance circuit and in the harness series resonating circuit to permit tracking of the antenna over a band of frequencies even where the input stages to the associated radio receiver are permeability-tuned and placed in series with the harnesses.

The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. The present invention, both as to its orginization and manner of operation, together with further objects and advantages thereof, may best be understood by reference to the following description, taken in connection with the accompanying drawinss, in which:

FIGURE 1 is a diagram of a first embodiment of the present invention.

FIGURE 2 is a second embodiment of the present invention showing both series and parallel tuning.

FIGURE 3 is an alternate form of the embodiment of FIGURE 2.

FIGURE 4 is a diagram of an embodiment utilizing both inductive and capacitive elements to attain a desired resonating characteristic.

FIGURE 5 shows the application of two parallel resonating circuits to a single relatively high-impedance area 10 bounded by a low-impedance conductive edge.

FIGURES 6a and b are diagrammatical variations of FIGURE 1.

FIGURE 7 shows an application of the present invention to a structural element made of insulating material.

FIGURE 8 is a diagram showing the application of the present invention to a corresponding structural element v hich is conductive.

FIGURE 9 shows diagrammatically, application of the principles of FIGURE 8 to a more complex embodiment. 20 In FIGURE 1, area 10, bounded by conductive edge 11, exhibits a relatively high impedance to the flow of electrical currents therethrough and may constitute either an opening in a conductive structure, uncovered or covered by an insulating material, or may be an area of relatively 25 high impedance induced by the application of specially prepared comminuted iron particles (ferrites) to the area. As has been indicated in the earlier filed copending applications to which reference has been made herein, radio frequency currents are found to circulate along conductive 30 edge 11 and a potential difference is found to exist between points such as points 12 and 13. By connecting condenser 14 of the proper capacitive value between points 12 and Ϊ3 through conductor 15 a resonant circuit may be formed comprising edge portions 16, 22 and 23 of conductive 35 edge 11, conductor 15 and capacitor 14. As a result of this resonance, a voltage gain is attained across capacitor 14, and, therefore, a higher voltage is developed across points 19 and 24 of harness 17. Similarly, a higher voltage is developed across points 19 and 13, with the peak 40 voltage appearing between points 19 and 18. Since harness 17 is coupled across condenser 14, the maximum voltage drop appears across the ends of harness 17. Outer sheath 20 of harness 17, to which the voltage appearing across condenser 14 is applied, constitutes the primary 45 of an auto-transformer, the secondary of which includes a plurality of turns of wire 21 which ultimately emerges from sheath 20 for connection to an output cable 220. Thus a voltage gain is achieved partly through producing a parallel resonant condition by means of condenser 14 50 and partially by transforming the magnified voltage appearing across capacitor 14 through the auto-transformer action of the turns of wire 21. If desired, of course, capacitor 14 may be made variable and ganged with the tuning apparatus in any associated transmitter or receiver.

In FIGURE 2, outer sheath 25 of harness 26 is brought to parallel resonance by capacitor 27. Because outer sheath 25 constitutes the primary of a voltage step-up transformer, the resonating of the primary of this autotransformer results in obtaining a relatively large voltage 60 between wire 28 and the outer sheath of output cable 29.

Capacitor 38 series resonates with the inductance of conductor 31 to bring point 32 on harness 26 to the potential at point 33 on conductive edge 34. Thus the maximum driving voltage is impressed across outer sheath 25 of 65 harness '26, by lowering the impedance of the circuit from point 33 to point 32 through such series resonance. It should be noted that one or more additional harnesses may be installed along the edge 34 of area 35 and driven from other points along that edge in order to obtain a 70 signal which may be combined appropriatelv with the signal from harness 26 to provide omnidirectionality for the combined system.

3,036,293

In FIGURE 3, condenser 300 resonates with conductive edge 301 surrounding isolated area 302 to provide a voltage increase across condenser 308 which may be used to drive outer sheath 303 of harness 304, sheath 383 forms the primary of an auto-transformer, as described β earlier. In order to obtain maximum voltage drive for harness 304, series condenser 305 is inserted in driving lead 3®6 and is adjusted or is predetermined in value so as to series resonate with the inductance of conductor 306, thus lowering the impedance of the driving link in- io eluding conductor 306 and bringing outer sheath 303 to the. potential of point 307. Once again, several loops may be placed along edge 301, bounding area 302, so as to provide a plurality of signals having differing spacephase characteristics. Conductor 306 could be used as a 15 common connector to join both condensers 300 and 385 to point 3t!7 thus assuring maximum voltage drive for harness 304. The same use of conductor 386 could be made in the other embodiments.

The circuit of FIGURE 4 is similar to that of FIGURE 20 2 except .that in this case variable inductance portions have been included in series tuned conductor 31 and in outer sheath 25 of harness 26. The first of these variable inductors 400 is formed by a short section of copper tubing 401 into which a high permeability core 402 may be 25 moved mechanically an amount sufficient to reach the desired magnitude of inductance. A sheath of high permeability ferrite material is placed around a section of outer sheath 25 to raise the inductive reactance thereof and this section 483 of raised impedance is shunted by a 30 short section 404 of copper tubing into which a high permeability core 405 may be moved to raise the inductive reactance of such short section 484. Permeability tuning slugs 402 and 405 may be ganged to provide the desired tuning of the antenna system as the associated re- 35 ceiver or transmitter- is tuned. Of course, condensers 27 and 3® might also be made variable. As indicated in connection with FIGURES 2 and 3, additional harnesses may be positioned at various points along the edge 34 bounding area 35 so as to provide multiple signals having ⁴⁰differing space-phase characteristics. Of course, area 35 may have any desired shape. Also, in FIGURE 4, variable inductances 408 and 404 may comprise turns of wire instead of copper tubing, if greater inductive reactances are desired. Also harness .26 may be broken in the 45 region 4®3 and variable inductance 404 placed in series therewith to obviate the need for a ferrite sheath. Similarly lead 31 may be broken and variable inductance 400 inserted.

In FIGURE 5, area 500 may be an opening in a con- 50 ductive body either unfilled or filled with an insulating material, or may be an area over which the impedance to radio frequency currents is greatly increased by the application of a high-permeability iron or ferrite layer to the area. It is preferred that the area 500 as well as area 55 35 in FIGURES 2 and 4 and area 302 in FIGURE 3 be disposed horizontally particularly when more than one space-phased signal is desired. Area 580 is bounded by a conductive edge 581. Sections 502, 503, and 504 and opposite portions 509, 510, 512 and 513 of edge 501 are 60 shunted by the combination of condenser 505 and variable inductance 506 to form a parallel resonant circuit. Radio frequency signals of increased magnitude are taken through output cable 514 from across condenser 505. Rough tuning of the parallel resonant circuit is achieved 65 by selecting the proper value for condenser 505 and the final trimming of that value is accomplished by means of variable inductance 506 which may take the form of a conventional helix, slug tuned, or a section of a copper cylinder as shown diagrammatically in FIGURE 5. 70

Simultaneously, condenser 507 and variable inductance 508 may be used to tune to resonance the circuit including those two components, their inner connecting wires and edge portions 509, 510, 502, 503 and opposite portions 511, 504, 512, and 513 of conductive wedge 501. 75

Experiments have shown that the signals derived across condensers 505 and 507, respectively, have differing spacephase characteristics and when properly combined may be utilized to obtain omnidirectional effects in combination with associated radio receiving or transmitting apparatus.

In the discussion of FIGURES 1 through 4 and in the illustrations themselves, the harnesses are shown as spanning a portion of the isolated areas such as area 35. In the case where it is desired that the antenna techniques taught herein be applied to automobiles, for example, and the area 35 is a window opening, the harness may be secreted above the window opening with only one portion of the inductive sheath connected along the upper edge of the window opening. (Such an installation can be installed below or on the side of the window opening.) The remaining portion of the harness may be covered with any one of a number of ferrite materials to prevent its being loaded by adjacent masses of metal. This technique is shown in various embodiments in the copending application, Serial No. 522,777, filed in the name of the same inventor as this application.

In FIGURE 6, conductive area .600 is lined with a high permeability ferrite material 601 so as to permit the derivation of radio frequency signals. A portion 607 of conductive sheath 602 of harness 603 is shunted across the relatively high impedance area so that the driving voltage derived is applied to the conductive sheath which forms the primary of an auto-transformer, such primary being parallel tuned by condensers 604 to obtain maximum voltage from the system. Output voltage is supplied to conductor 606 of cable 685. A plurality of harnesses of the type illustrated may be disposed in desired directions across the high impedance area, formed by ferrite layer 601. To isolate harness portion 687 from the remainder of the harness that portion or the entire harness may be covered with ferrite material.

FIGURE 7 illustrates the application of the principles which have been described to a particular installation. In FIGURE 7, area 700 is a non-conductive trunk lid or other preferably horizontal member of an automobile, for example. A closed loop 701 may be formed around the perimeter of area 700 by means of a piece of copper tubing. Adjacent and connected to the copper tubing, there are placed two harnesses 702 and 703 oriented at right angles to each other. Conductive sheath 704 of harness 702 as shunted by contiguous sections of closed loop 701 or other conductive boundary may be resonated at the desired signal frequency by means of condenser 705. Correspondingly, conductive sheath 706 of harness 703 as shunted by contiguous conductive portions may be tuned to parallel resonance at a desired frequency by means of condenser 707. Copper tubing 701 has attached to it a number of wiper contacts 708 which make contact with the conductive body 709 of the automobile. The radio frequency signals normally intercepted by the closed loop comprising copper tubing 701 are supplied directly by the adjacent conductive structure to which wiper contacts 708 make connection when the trunk lid or door is closed, when the lid is open inductive and direct coupling between the harnesses and the adjacent conductive body remains though somewhat reduced in magnitude.

FIGURE 8 illustrates the technique for achieving good radio frequency signal reception where the trunk lid or door is metallic. Door 800 is severed in areas 801, 802, 803 and 804, and an insulating reinforcing rib is inserted for each portion of metal removed. Once again, a closed loop 805 may be fastened to lid 800 along its periphery so as to provide a constant signal source which is augmented by the additional radio frequency currents coupled into the system when wiper contacts 806 connect with the adjacent metal portions of the automobile body. Any of the harness configurations previously described may be adapted to this embodiment.

In FIGURE 9a is shown a top view of a metallic body

3,066,293 ⁵ having an upper surface 913 segmented to form leaves 902, 903, 904, 905, 906, 907, 908 and 909 or any greater or lesser number of segments which are desired for a given application. The purpose of the multiple segments or leaves is to make it possible to· obtain signals having 5 various space-phase relationship and raise the impedance of the area to a desired level. Opposite tips of the segments are joined by a condenser, as for example, segments 903 and 907 are joined by condenser 910, which produces a parallel resonant condition. Adjacent seg- 10 ments such as 906 and 907 may be joined by condensers such as condenser 911 to tune out the inductive reactance of such segments. Output signals are taken from across condenser 910 through output cable 912. Instead of actually cutting the metal the areas may be made to appear isolated by means of high permeability ferrite strips placed radially about a center area which is also lined with ferrite material. In the area of the ferrite materials, the metal has a relative high impedance so as to simulate an actual opening in the metal. Parallel resonance of the elements is again produced to provide maximum voltage for driving the associated receiving apparatus or for driving harnesses which may be coupled into the circuit in the fashion previously described or for optimum transfer from transmitter to the mass. This configuration and others described in this and former applications may be used in other than horizontal installations if desired.

It is to be understood that as desired operating frequencies vary, the length and separation of segments may be varied to provide optimum performance. As the frequency of operation increases, the length of the segments or leaves decreases, until in the ultimate condition the segment length becomes infinitesimal and there is left merely an opening ferrite isolated area or an appropriate section of the body itself across which connections may be made directly to the input electrodes of a vacuum tube, transistor or other translating device, the only element of the resonant input circuit being the resonated body area or opening itself if so desired. For producing ⁴⁽¹resonance of the segments, harness and adjoining body portions at low radio frequencies while retaining reasonable leaf length, the magnitude of capacitance 910 may be increased. Values as high as .155 mfd. have been used in practice with excellent voltage gain in the circuit.

In FIGURE 9b there is shown a possible cross sectional configuration for a tank or cavity 901 having an upper surface similar to that shown in FIGURE 9a. The area and volume of this cavity may be chosen to give optimum signal reception at a desired frequency. A cavity of this type may be submerged in the earth or in water with the upper surface of the tank flush with or protruding slightly above the surrounding medium. If desired cavity 901 maj' be made electrically discontinuous below point 915, which may be at any desired point on body 901. This will reduce the shunting of opening 900 and provide greater signal output and transfer.

Thus, there has been provided by this invention an improved antenna apparatus for use with signal transmitting or receiving apparatus wherein maximum coupling to and from the signal intercepting area is achieved through the production of parallel and series resonance in circuits utilizing selected areas of a fixed or mobile structure which forms an integral part of the antenna apparatus.

While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from this invention in its broader aspects, and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.