US3007164A

US3007164A - Slot antenna which is fed at two points

Info

Publication number: US3007164A
Application number: US503190A
Authority: US
Inventors: Ross A Davis
Original assignee: Individual
Current assignee: Individual
Priority date: 1955-04-22
Filing date: 1955-04-22
Publication date: 1961-10-31
Anticipated expiration: 1978-10-31

Description

Oct. 31, 1961 R. A. DAVIS 3,007,164

SLOT ANTENNA WHICH IS FED AT TWO POINTS Filed April 22, 1955 3 SheetsSheet 1 iiili 3 37 F |G.6 1 R088 A. DAVIS IN VEN TOR.

HIS ATTORNEY R. A. DAVIS SLOT ANTENNA WHICH IS FED AT TWO POINTS Oct. 31, 1961 3 Sheets-Sheet 2 Filed April 22, 1955 FIG-7- l-llllll Llllllll E V m A S S O R IN V EN TOR.

HIS ATTORNEY 3 Sheets-Sheet 5 HIS ATTORNEY Oct. 31, 1961 R. A. DAVIS SLOT ANTENNA WHICH IS FED AT TWO POINTS United States Patent 3,007,164 SLOT ANTENNA WHICH IS FED AT TWO POINTS Ross A. Davis, Los Angeles, Calif.

(235 Sunridge St., Playa Del Rey, Calif.) Filed Apr. 22, 1955, Ser. No. 503,190

11 Claims. (Cl. 343-712) This invention is directed to transmitting or receiving antennas for structures and, more particularly, to antenna systems actively utilizing radio frequency currents flowing along the conductive boundaries or borders surrounding discontinuities or electrically non-conductive spaces in the structures, be they mobile or fixed structures. The invention covered herein differs from that covered in my co-pending application, Serial No. 487,535, filed February 11, 1955, Patent No. 2,923,813, granted February 2, 1960, and entitled Antenna Systems in the structure and circuitry by which the antenna systems and associated receiver circuitry accomplish uniform translation of radio frequency signals independent of the direction of their origin.

Therefore, it is one object of this invention to provide a simple antenna system utilizing the radio frequency current flowing in a metallic boundary or border about a discontinuity or electrically non-conductive space in the structure carrying the antenna in such a fashion as to derive a pair of signals having a desired space phase relationship.

It is a further object of this invention to provide an antenna system for the transmission or reception of radio frequency energy in which the transfer of such energy to or from two space-phased portions of the antenna system are utilized in a sequential fashion to provide pseudoomnidirectionality.

According to the present invention a plurality of spacephased radio frequency signals are derived from each of one or more metal-bounded spaces in a conductive structure such as a vehicle. The terms opening, space and discontinuity are used interchangeably herein and are intended to refer to any region of high electrical impedance at least partially bounded by an electrically conductive three-dimensional body. Part of the extraction of radio frequency energy from the conductive boundary material is derived by a pair of exciter conductors which span the discontinuity in such a fashion that they are nonparallel or angulated, and, in a special case intersect each other within the discontinuity. Harnesses of the type disclosed in the co-pending application already referred to may be combined with this angulated exciter wire technique to enhance the voltage coupling to adjacent circuitry. Dual channels may be utilized if desired. Sequential coupling of each pick-up system to adjacent receiver circuitry may be accomplished by a motor driven condenser rotor having plates of predetermined shape rotating sequentially into two sets of stator plates of corresponding configuration. The combination provides an antenna which is signal-sensitive non-directional in its apparent effect, permits derivation of two space-phased signals from a single planar opening, exhibits an absolute minimum of electrostatic noise interception and a maximum freedom from fadeouts when used for reception of signals within structures normally effecting high degrees of shielding from radio signals, as for example, tunnels.

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 organization and mannerpof operation, together with further objects and advantages thereof, may best be understood by reference to the following description, taken in connection with the accompanying drawings, in which:

FIGURE 1 is a diagrammatic showing of one antenna system according to this invention.

FIGURE 2 is a sketch of a second form of an antenna system according to this invention.

FIGURE 3 is a schematic representation of an improved form of the antenna system shown in FIGURE 1.

FIGURE 4 is a diagrammatic representation of an improved form of the antenna system of FIGURE 2.

FIGURE 5 is a schematic representation of a third form of the present invention with associated receiver circuitry shown in schematic form.

FIGURE 6 is a schematic showing of a modification of the antenna system of FIGURE 5.

FIGURE 7 is a modification of the antenna system shown in FIGURE 5.

FIGURE 8 is a modification of the antenna system shown in FIGURE 2.

FIGURE 9 shows a sequential selector for use with the antenna systems of this invention.

FIGURE 10 shows the application of the antenna system of FIGURE 1 to a specific discontinuity or space.

FIGURE 11 is a schematic representation of another embodiment of the present invention.

FIGURE 12 is a schematic representation of the use of this invention to high frequency applications.

FIGURE 13 is a modification of the embodiment of FIGURE 12.

FIGURE 14 is a further modification of FIGURE 5.

In FIGURE 1, opening discontinuity or space 10 is bounded by the conductive boundary or border of threedimensional body 11. Conductor 12 is connected to point 13 on the border of body 11 and the R-F energy appearing at point 13 is applied to output coaxial line 14 at its inner conductor 15. The outer conductor or sheath 16 of coaxial line 14 is grounded to the conductive border of body 11 at point 17 which is on the opposite side of space 10 but is not directly opposite point 13. Conductor 18 is connected to point 19 on the conductive boundary of body 11 and traverses space 10 to connect to inner conductor 20 of coaxial line 21 and the outer sheath 22 of which is connected to the conductive boundary of body 11 at point 23.

Conductors

12 and 18 may be made of extremely fine wire so as to make them completely inconspicuous. Experiments have shown that it is preferable that the conductive boundary of body 11 not lie in an absolutely vertical plane. A closed loop of the type which is formed by boundary of body 11 appears to favor the magnetic field component of the horizontally polarized electromagnetic waves and reject other components including undesirable noise fields, and the more nearly the average plane of the boundary of body 11 can be made horizontal the greater the efficiency of the closed loop where multiple signals are derived from one opening.

In FIGURE 2 there is shown an antenna system which is a special case of the structure shown in FIGURE 1 in that exciter

wires

12 and 18 intersect at right angles in opening or space 10 and connect to the conductive boundary of body 11 at points 24 and 25, respectively. In addition, outer conductor or sheath 16 of output cable 14 is connected to the conductive boundary of body 11 at point 26 and outer sheath 22 of output coaxial cable 21 is connected to the conductive boundary of body 11 at point 27. As has already been indicated, it is desirable, but not essential, that the conductive boundary of body 11 lie in an average plane which is not absolutely vertical by reason of the fact that the closed loop which the conductive boundary of body 11 constitutes has been found to favor horizontally polarized electromagnetic Waves. Of course, the conductive portions of the structure which are horizontal and contiguous to the conductive boundary of body 11 effectively modify the orientation of the loop formed by the conductive boundary of body 11 to give it a horizontal component. The configuration shown in FIGURE 2 will provide two signals which are substantially in space phase quadrature.

In some cases it may be desirable to produce voltage multiplication of the radio frequency signal which is found across space 10. The voltage multiplying harness technique shown broadly in the co-pending application previously referred to may be adapted for this purpose. Such an adaptation is shown in FIGURE 3, in which, exciter wire 18 is connected to conductor 30 which passes through conductive sheath 31. Conductive sheath 31, in turn, is positioned closely adjacent the conductive boundary of body 11 surrounding space and extends substantially half the length of each of the adjacent two intersecting sides of the boundary.

Reference to the earlier filed application will show that in the embodiments shown there the harnesses in most cases extend from a point along the lower portion of the conductive boundary of body 11 to a point substantially opposite across space 10. In the embodiment of FIGURE 3 of this case the effect of the longer harness is obtained, without traversing this total distance, by folding the harness back on itself and enclosing it in ferrite sheath 34. The connection of exciter wire 18 to wire 32 raises the potential at the output end of ferrite sheath 34 to a level equivalent to that it would attain if the harness had been continued around the window. To reduce confusion conductor 30 is shown as having a single loop through conductive sheath 31 and ferrite sheath 34, but to gain voltage multiplication several turns should be utilized. The voltage taken from the harness is applied to the inner conductor 35 of output cable 36. Similarly, exciter wire 12 is connected to conductor 37 which passes through conductive sheath 38 and returns through ferrite sheath 39 either for re-passage through conductive sheath 38 or coupling to external circuits through inner conductor 40 of output cable 41. Exciter wire 12 is also connected to wire 42 which is connected to the remote end of conductive sheath 38 at point 43. Conductive sheaths 31 and 38 may be connected to points 44 and 45, respectively, on the conductive boundary of body 11. The amount of voltage multiplication obtained in either of the harness arrangements may be controlled by varying the number of times conductor 30 or conductor 37, respectively, passes through conductive sheaths 31 or 38, respectively. An excessive number of turns makes tracking of associated antenna tuning circuits diflicult, however, so an optimum number of turns must be chosen. This can be determined by experimenting with the particular associated tuning circuits involved.

The same harness concept may be applied to the embodiment of FIGURE 2 and the results are shown in FIGURE 4, in which, exciter wire 18 is connected to conductor 46 which passes through conductive sheath 47. Conductive sheath 47' lies adjacent the conductive boundary of body 11 and, at its extremities, is connected to that boundary as, for example, at points 48 and 49 in FIGURE 4. When conductor 46 emerges from the remote end of conductive sheath 47, it returns to the region of the input end of conductive sheath 47 and may pass through that sheath a plurality oftimes so as to provide a desired voltage amplification when it ultimately is connected to inner conductor 400 of output cable 401. In order to isolate conductor 46 on its return le ferrite sheath 402 may be provided. Exciter wire 18 is also connected to wire 403 which, in turn, is connected to the remote extremity of conductive sheath 47 in the region, of point 404.

Exciter wire 12 is connected to conductor 405 which passes through conductive sheath 406 and returns through ferrite sheath 407 either for re-passage through conductive sheath 406 or for connection to inner conductor 408 of output coaxial cable 409. Wire 410 may also be provided. Conductive sheath 406 is connected to the conductive boundary of body 11 at

points

411 and 412. The configuration of FIGURE 4 provides two relatively high amplitude radio frequency signals having a spacephase quadrature relationship.

Some improved performance may be obtained by passing the trimmer connections as well as the tuning inductor connectors through the harnesses. One embodiment of this concept is shown in FIGURE 5 in which exciter wire 500 is connected to inner conductor 501 of double conductor line 502, the remote end of conductor 501 being coupled to antenna tuning inductor 503. The remaining end of exciter wire 500 is connected to conductive sheath 504 of harness 505 at point 506. Exciter wire 507 is connected to point 508 on the conductive boundary of body 11, as is the outer sheath 509 of double conductor line 502. The remaining end of exciter wire 507 is connected to conductor 510 which passes through conductivce sheath 504 of harness 505 and ultimately is connected to the second inner conductor 511 of double conductor line 502. The remote end of conductor 511 is coupled to trimmer capacitor 512 and outer sheath 504 is connected to the conductive boundary of body 11 at point 513. By this technique out-of-phase R-F voltages are applied to the trimmer and tuning inductors in the associated receiving apparatus. Similarly, harness 514 provides a pair of properly phased signals for trimmer 515 and tuning inductor 516 of a second antenna input circuit of an associated receiver, if dual channels are utilized.

Harnesses

505 and 514 lie adjacent the conductive boundary of body 11. Either conductor 500 or 507 may be a hollow rod through which the other passes.

In FIGURE 6 harnesses 600 and 601 are isolated physically and magnetically from conductive body 11. The magnetic isolation is accomplished by means of a ferrite sheath covering each of the harnesses. Signals from exciter wires 602 and 603 are utilized to excite the trimmer circuits of associated receivers whereas exciter wires 604 and 605 are utilized to excite harnesses 600 and 601.

In FIGURE 7, no harnesses of the variety shown in FIGURE 6 are utilized. Exciter wire 700 is connected at one end to point 701 on conductive boundary 11 and at the other end to conductive sheath 702 of output coaxial cable 703. A ferrite sheath may be provided on cable 702. Exciter wire 704 is connected between point 705 on body 11 and inner conductor 706 of coaxial output cable 707. The inner conductor 708 of output coaxial cable 703 is connected to body 11 at point 709. The outer sheath 7.10 of coaxial output cable 707' is connected to body 11 at point 711. The remote end of inner conductor 708 is connected to a trimmer condenser in associated receiving apparatus whereas the remote end of inner conductor 706 of output coaxial cable 707' is. connected to. a tuning conductor in associated receiving apparatus. These may be interchanged. In corresponding fashion a pair of signals is derived from

points

712 and 713 for application to the trimmer condenserand tuning inductor circuits of associated receiving ap-. paratus in a dual channel system. In a dual channel system the signals are translated independently through a predetermined number of stages, and then combined.

If it is desired that; this technique of deriving both trimmer condenser return and tuning inductor poten-. tials from the conductive boundary of body .11, the structure of FIGURE 8 may be utilized. In FIGURE 8, exciter wire 800 is connected to body 11 at point 801 and its other extremity is connected to conductor- 802 in conductive sheath 803. The remote end of conductor 802 may be connected to an input tuning inductor in an associated dual channel receiving system. Exciter wire 804 is connected to point 805 on body 11 and at the other end to conductor 806 which passes through conductive sheath 807 and, subsequently through conductive sheath 803 for connection to the trimmer circuit and associated' receiving apparatus. Conductive sheaths 80.7 and 803 are connected to

points

808 and 809, respectively, on the conductive boundary of body 11.

Exciter wire 810 is connected to point 811 on body 11 and to conductor 812 which passes through conductive sheath 813 for ultimate connection to a trimmer condenser and associated receiving apparatus. An -extension of conductive sheath 813 is connected to body 11 at point 811. Exciter wire 814 is connected at one end to point 815 on the conductive boundary of body 11, to which conductive sheath 813 is also connected, and at the other end to conductor 81 6 which, at its remote end, is coupled to a tuning inductor and associated receiving apparatus. Thus, both trimmer and tuning inductor radio frequency voltages may be derived which are in space phase quadrature with a second set of trimmer condenser and tuning inductor R-F voltages. The conductive sheath may be eliminated if proper positioning of wire 812 is eflected.

While frequent mention has been made of a dual channel receiver associated with the antennas described herein, it may be desirable to utilize these antennas with a single channel receiver by applying a sequential technique. A mechanism by which sequential coupling of the space-phased R-F signals to associated single channel receiving apparatus may be eifected is shown in FIG- URE 9. In that figure there is provided a rotary capacitor comprising a plurality of sets of vanes 900 acting as a first set of stator plates and insulated and angularly displaced from a set of stator plate vanes 901, the space between successive stator plates in

stators

900 and 901 being sufiicient for passage of rotor vanes 903 having the same general sectorial shape as the stator plates. The rotor plates are insulated in conventional fashion from the stator plates. R-F signals provided by exciter wire 904 are applied to inner conductor 905 of output cable 906 and at the remote end are applied to stator plates 900. Similarly, R-F voltages appearing on exciter wire 907 are applied to inner conductor 908 of coaxial connector 909 and at the remote end are applied to stator plates 901; Connection is made to rotor plates 903 through sliding, or other appropriate contact, 910 and the signals appearing on rotor 903 are taken through conductor 911 to associated receiving apparatus. The stator plates 901 are displaced angularly with respect to stator plates 900 so as to, in effect, fill the gaps between successive segments or vanes of stator 900. As rotor plates 903 rotate they pass from a condition in which they are closely coupled to stator plates 900 to a condition Where they are closely coupled to condenser plates 901 and there is a resulting sequential coupling of exciter wires 904 and 907 to external receiving apparatus. Exciter wires 904 and 907 provide R-F signals having a predetermined space phase relationship so that if space 10 is in the body of a moving vehicle and that vehicle changes its direction, the relative amount of signal appearing on exciter wires 904 and 907 will vary in a compensating fashion, that is, one will rise as the other falls, and the net signal supplied to the associated radio receiving apparatus will appear to be substantially constant, the variations being sufliciently small so that the ordinary AVC system in the associated receiving apparatus will compensate for the amplitude variations and the person listening to the receiver will be relatively unaware of any change in signal strength as the vehicle is turned. This same technique may be applied in the case of transmitting apparatus except that power would be flowing towards wires 904 and 907. By increasing the number of vanes in each set and, hence, by decreasing the sectorial angle covered by each vane, the rate of sequential supply 01: signals to or from adjacent apparatus can bemade so high as to produce a superaudible beat frequency thus making the amount of objectionable interference produced by this technique a minimum. The selector may be connected to a later point in the circuit. It eliminates the need for a dual .for the rotary condenser. Electric, pneumatic, hydraulic or other types of drive motors may be utilized, or the selector may be driven by an operating member of the car itself. Further, sliding contacts'to rotor 903 may be eliminated by providing a separate end stator plate which is a full circle instead of a segment of a circle, is insulated from the remaining stator plates or vanes and is positioned adjacent an end rotor plate or series of rotor vanes. This same elimination of sliding contact with the rotor may be efiected by taking each set of stator vanes and insulating one-half of such vanes from the other half so as to produce a split stator construction in both sets of vanes. The rotor vanes then constitute the coupling means between the two halves of each set of stator vanes and no connection is made to the rotor at all. Of course, a mechanical commutator may be utilized. The eifects of intercoupling between sets of stator vanes may be minimized by spacing or shielding the sets, or by providing additional sets and applying signals from additional points on body 11.

If electronic selection is desired, a pair of gate tubes, one in each of the channels from each of the two antennas may be activated alternately utilizing successive half cycles of an oscillator operating at a supersonic frequency. The frequency may be chosen to be a subharmonic of the desired superheterodyne local oscillator frequency of the associated receiver, thus reducing the cost of the over-all circuitry.

In the general case, space 10 need merely be surrounded by the conductive body 11. In the specific case as applied to automobiles, a great number of discon tinuities or spaces exist from which very satisfactory radio frequency signals have been derived. Tests have shown that the further the space is from the automobile engine, the better will be the signal-to-noise ratio in the associated receiving apparatus. Innumerable discontinuities or spaces have been used and some have been described in the co-pending application previously referred to.

In FIGURE '10 there is shown a specific discontinuity or space which has provided a very satisfactory signal. In FIGURE 10 exciter wire is connected to point 101 on fender 102. Its other end is connected to inner conductor 103 of cable 104. Exciter wire 105 is connected to point 106 on the under side of fender 102. The remaining end of exciter wire 105 is connected to inner conductor 107 of cable 108 and exciter wires 100 and 105 have an angulated relationship with respect to each other and may intersect within the discontinuity below fender 102. Outer sheaths 109 and 110 are connected to points 111 and 112 on body 113 of the vehicle which is mechanically and electrically directly connected to tender 102 to form a closed loop therewith. Thus a signal is derived from a cavity below the fender 102. In FIGURE 11 there is shown the structure for deriving from the region between the body, :gas tank and splash pan the desired two spaced-phased signals. Harness 115 includes'conductive shield 116 which is connected at one extremity to point 117 on gas tank 118. Conductive sheath 116 also is grounded to the body of the vehicle at point 119 and at point 120, proceeding in an upwardly direction from the connection at point 117. Bracket 122 extends downwardly from splash pan 123 for connection to exciter wire 124, the remote end of which is connected to conductor 125 in ferrite sheath 126. Wire 125 passes through conductive sheath 116 and ferrite sheath 126 a plurality of times depending upon the voltage multiplication desired. Its origin is connected to conductive sheath 116 at point 127 and its output end is connected to inner conductor 128 of output cable 129.

Harness 130 includes conductive sheath 131 which has one end connected to gas tank 118 in the region of point 117 and is disposed in an L-shape extending upwardly to connect to the body of the vehicle at point 132 and again in the region of tender 133 at point 134. Conductor 135 has one end connected to conductive sheath 131 in the region of point 134 and traverses several loops through ferrite sheath 136 and conductive sheath 131 for ultimate connection to inner conductor 137 of output cable 138 which has its outer sheath connected to substantially point 117 on gas tank 118. Energizing or exciting wire 139 is connected between point 140 on feeder 133 and point 141 on conductor 135. It is to be noted that the exciter wires are angulated with respect to each other and that the ferrite sheaths permit the return wires of each of the harnesses 130 and 115 to lie closely adjacent portions of the conductive members of the vehicle without undue loading of the return wires. A pair of spacephased radio frequency signals will be derived from this combination. Experiment has shown them to be of high intensity and relatively free of any automobile noises. The ferrite sheaths 126 and 136 may be eliminated if harnesses 115 and 130 are not folded back upon themselves as shown in FIGURE 11.

Discussions thus far have dealt with the applications of the principle of this antenna to broadcast frequency operation. If it is desired to extend the concept to the higher frequencies, for example those utilized in connection with frequency modulation transmissions, certain modifications are required. The primary problem which is encountered is that of properly matching into the impedance of the conductive boundary of body 11. Techniques for accomplishing the desired matching are shown in FIGURES 12, 13 and 14.

In FIGURE 12 inner conductors 170 and 171 of output cable 172, or extensions of those inner conductors, are fanned outwardly as shown and connected to

points

173 and 174 on body. 11. These points may be chosen empirically to give the desired impedance match between the output cable and the closed loop which the conductive boundary of body 11 constitutes.

In FIGURE 13

inner conductors

180 and 181 of cable 182 are spread directly on their emergence from cable 182 and connected to

points

183 and 184, respectively. The outer conductive sheath 185 of cable 182 is connected to body 11, as shown.

The connections shown in FIGURES l2 and 13 provide only a single, directional signal. If dual, spacephased signals are required, the cables and connectors may be duplicated and connected to two additional predetermined points on body 11 spaced from the initial points.

In FIGURE 14 there is shown a simplified approach to the problem of deriving trimmer potentials which are out of phase with the tuning inductance signals. Wire 190 which may be an extension of inner conductor 191 of output cable 192 is connected to point 193 along the inner boundary of body 11. The remote end of inner conductor 191 may be connected to a selector of the type shown in FIGURE 9. Wire 194 is connected to point 195 on body 11 and its remaining end is connected to innerconductor 196 in output cable 197. At its remote end inner conductor 196 is connected to the remaining stator plates in a selector of the type shown in FIG- URE 9. An out-of-phase trimmer exciting connection is made to point 198 through wire 199 which connects to inner conductor 200' of cable 201.

Wires

190 and 194 may be connected to a pair of conductors within a single conductive sheath. Wire 199 may be returned through a brace member of a car window to which has been applied a sheath of ferrite material so as to raise its impedance. Other discontinuities or spaces which have been found useful are for example, below the rear window and behind the rear seat, between the rear of the chassis of the automobile and the bumper, and, of course, across the various windows, particularly, the rear window of the vehicle and the overhead, plastic covered window provided in some modern automobiles.

Thus, there has been provided by this invention a numher of embodiments of antenna systems for use with structures having electrically non-conductive discontinuities, openings or spaces bounded by conductive boundaries or borders in which one or more exciter wires are disposed in angular relationship with respect to each other and having at least one end of each such conductors or wires connected to the conductive boundary around the discontinuity or space, the remote ends of the exciter wires being coupled either without modification or with transformation in special harnesses to associated receiving apparatus either of a dual channel variety or a single channel variety. In the latter case, a sequential technique is involved and a rotary condenser technique for accomplishing the selective and sequential excitation of the remote receiving apparatus from the dual sources is provided.

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.

I claim: I

1. An antenna system including a three-dimensional electrically conductive body having an opening therein; a pair of exciter wires each having one end coupled to said body at spaced points adjacent said opening, said wires being positioned in angular relationship with respect to each other and spanning said opening; a pair of harnesses positioned in proximity to said body and adjacent said opening and each comprising a conductive sheath coupled at one end to said conductive body; a ferrite sheath lying adjacent each conductive sheath and constituting the return leg of the associated harness; a first conductor passing through the conductive and ferrite sheaths of one of said harnesses; and a second conductor passing through the conductive and ferrite sheaths of the other one of said harnesses, each of said conductors having one end coupled to one of said exciter wires, its remaining end being adapted for coupling to associated radio-frequency circuitry.

2. An antenna system according to claim 1 in which said exciter wires spacially cross each other within said opening.

3. An antenna system according to claim 1 in which said exciter wires spacially cross each other at an angle of substantially 4. An antenna system according to claim 1 in which said opening is a window.

5. An antenna system according to claim 1 in which said conductive body is an automobile body and said opening is a window.

6. An antenna system according to claim 1 in which said body is an automobile body and said opening is at the lower end of a fender cavity.

7. Apparatus as defined in claim 1 in which each of said conductors passes through its respective conductive and ferrite sheaths a plurality of times.

8. An antenna system including a three-dimensional electrically conductive body having an opening therein; first and second exciter wires each having one end directly coupled to said body at spaced first and second exciter points, respectively, adjacent said opening, said exciter wires spacially crossing each other within said open ing; and first and second leads each having one end coupled directly to said body at spaced first and second lead points, respectively, adjacent said opening, said first and second exciter points and said first and second lead points being so disposed with respect to each other that voltages appearing between said first exciter point and said first lead point are space phase displaced with respect to voltages appearing between said second exciter point and said second lead point, thereby obtaining omnidirectionality, and the remaining ends of said exciter wires and leads being adapted for coupling to external circuits.

9. An antenna system including a three-dimensional electrically conductive body having an Opening therein; first and second exciter wires each having one end directly coupled to said body at spaced first and second exciter points, respectively, adjacent said opening, said exciter wires spacially crossing each other at an angle of substantially 90; and first and second leads each having one end coupled directly to said body at spaced first and second lead points, respectively, adjacent said opening, said first and second exciter points and said first and second lead points being so disposed with respect to each other that voltages appearing between said first exciter point and said first lead point are space phase displaced with respect to voltages appearing between said second exciter point and said second lead point, thereby obtaining omnidirectionality, and the remaining ends of said exciter wires and leads being adapted for coupling to external circuits.

10. An antenna system including a three-dimensional electrically conductive body having an opening therein; first and second exciter wires each having one end directly coupled to said body at spaced first and second exciter points, respectively, adjacent said opening, said exciter wires being positioned in angular relationship with respect to each other and spanning said opening; and first and second leads each having one end coupled directly to said body at spaced first and second lead points, respectively, adjacent said opening, said first and second exciter points and said first and second lead points being so disposed with respect to each other that voltages appearing between said first exciter point and said first lead point are space phase displaced with respect to voltage appearing between said second exciter point and said second lead point, thereby obtaining omnidirectionality, and the remaining ends of said exciter wires and leads being adapted for coupling to external circuits.

11. An antenna system including a three-dimensional electrically conductive body having a discontinuity therein; first and second exciter conductors each having one end directly coupled to said body at spaced first and second exciter points, respectively, adjacent said discontinuity, said exciter conductors being positioned in angular relationship with respect to each other; and first and second leads each having one end coupled directly to said body at spaced first and second lead points, respectively, adjacent said discontinuity, said first and second exciter points and said first and second lead points being so disposed with respect to each other that voltages appearing between said first exciter point and said first lead point are space phase displaced with respect to voltages appearing between said second exciter point and said second lead point, thereby obtaining omnidirectionality, and the remaining ends of said exciter conductors and leads being adapted for coupling to external circuits.

References Cited in the file of this patent UNITED STATES PATENTS 2,131,108 Lindenblad Sept. 27, 1938 2,193,500 Usselman Mar. 12, 1940 2,320,124 Forbes May 24, 1943 2,481,978 Clough Sept. 13, 1949 2,575,471 Schweiss et al. Nov. 20, 1951 2,632,851 Lees et a1 Mar. 24, 1953 2,687,475 Sheldorf Aug. 24, 1954 2,695,406 Byatt Nov. 23, 1954 2,825,061 Rowland Feb. 25, 1958 FOREIGN PATENTS 1,012,833 France July 17, 1952