US2963701A

US2963701A - Electrically steerable horn antenna system

Info

Publication number: US2963701A
Application number: US686213A
Authority: US
Inventors: Boynton G Hagaman
Original assignee: ANTENNA SYSTEMS Inc
Current assignee: ANTENNA SYSTEMS Inc
Priority date: 1957-09-25
Filing date: 1957-09-25
Publication date: 1960-12-06
Anticipated expiration: 1977-12-06

Description

Dec. 6, 1960 B. e. HAGAMAN ELECTRICALLY STEERABLE HORN ANTENNA SYSTEM Fil'ed Sept. 25, 1957 2 Sheets-Sheet 2 enm WZQQNTI 29.2810 n5 M GZQ ..N\

90 N/ 073/;1 NOLLV/OVH NI 073/4! NOLLV/OVZ INVENTOR I ATToibiE Y United States Patent ELECT RICALLY STEERABLE HORN ANTENNA SYSTEM Boynton G. Hagaman, Alexandria, Va., assignor to Antenna Systems, Inc., Washington, D.C., a corporation of Delaware Filed Sept. 25, 1957, Ser. No. 686,213

9 Claims. (Cl. 343-100) The present invention relates to an electrically steerable horn antenna system and particularly to a feed system for a horn antenna which provides electrical steering of the major radiation lobe with respect to the major horn axrs.

An object of the present invention is to provide a horn antenna system in which the directivlty is controllable over both the E and H planes of the horn and in which the major beam dimensions are not materially altered during steering.

Another object of the invention is to steer the radiation of the horn antenna in either, or both, the E and H planes simply by electrical adjustment of components in the horn feed system, Without the necessity of moving the horn or other mechanical elements.

Another object of the invention is to provide electrical steering of the radiation of a horn antenna mounted several wave lengths above the earth in such a manner that over a range of frequencies, the usual variation in elevation or departure angle caused by the earths reflections is eliminated.

According to the invention, the radiation of the horn antenna is steered or shifted by feeding the horn with a plurality of probes which are spaced apart in the direction of the E vector or the H vector, or both, and the phases of the energy of the several probes are adjusted relative one to the other so as to obtain a desired direction of radiation from the horn.

The invention will be fully understood and the above other objects and advantages of the invention will become apparent from the following description and the drawings in which:

Fig. 1 is a schematic view of one embodiment of the invention;

Fig. 2 shows radiation patterns obtained with the arrangement illustrated in Fig. 1;

Fig. 3 shows another embodiment of the invention for steering the beam in the H plane;

Fig. 4 shows a radiation pattern obtained with the arrangement shown in Fig. 3; and

Fig. 5 shows another embodiment of the invention for steering the radiation in both the E and H planes.

Referring to Fig. 1, there is shown a pyramidal horn having a wave guide section 11. The wave guide 11 is provided with a bisecting metallic partition 12, lying in the H plane, which is here the vertical plane. Wave guide section 11 is closed at one end by a metallic wall 14. A pair of

probes

15 and 16 extend through

opposite side walls

17 and 18. Probe 15 is connected to a generator or a receiver 19 by a radio frequency transmission circuit which may consist of transmission lines 20 and an impedance matching and/ or attenuation pad 21. Probe 16 is similarly connected by transmission line 22 to a pad 23 and then through a variable phasing network 25 to the generator or receiver.

Probes

15 and 16 are arranged and have a length such that wave guide 11 is excited in a TB 10 mode. Simple aligned probes may be used where 2,963,701 Patented Dec. 6, 1960 ice band-width requirements are moderate, however, the system may be made capable of handling broad frequency hands by any of the usual methods.

Phasing network 25 has a nominal phase delay of this being necessary since the probes are fed from opposite ends. If the phasing network 25 is adjusted to provide additional phase delay of the energy fed to probe 16, the radiation from the horn will be steered in the direction toward probe 16. Fig. 2 illustrates the directivlty control obtained with progressive increments of phase delay in network 25. Each curve shows the radiation pattern of the beam for a particular setting of phasing network 25. The amount of steering or turning of the beam in Fig. 2, is approximately 10, as represented by the angular shift to the left of the peaks of the curves from curve 26 to curve 27. Similar shifting of the radiation pattern in the opposite direction is obtained by relative delay of the energy fed to probe 15. The steering represented in Fig. 2, is in the E plane or the azimuthal direction.

Fig. 3 shows another embodiment of the invention in which a pyramidal horn 30 is connected to a wave guide section 31. A pair of probes 32 and 33 are located at approximately one third the distance h from the top and the bottom of the wave guide. The distance h is to be at least equal to one wave length at the operating frequency. Probe 32 is connected by a transmission line or equivalent radio frequency path 34 to a generator or receiver and probe 33 is similarly connected through a transmission line 35 and an adjustable phasing network 36 to a generator or receiver 37. It will be understood that suitable radio frequency pads may be included in

transmission lines

34 and 35 as indicated in Fig. 1.

Fig. 4 shows the steering of the radiation beam in the vertical or the H direction which is obtained with the arrangement illustrated in Fig. 3. Curve 40 shows the radiation pattern of the horn antenna when phasing network 36 is adjusted to zero delay or, in other words, when probes 32 and 33 are energized in the same phase.

Curves

41, 42 and 43 show the progressive shifting of the radiation pattern as network 36 is adjusted to increase the phase delay. Similar shifting of the radiation pattern in the opposite direction is obtained by a relative delay of the energy fed to probe 32.

Horn antenna 30 may be placed several wave lengths above the earth with its axis horizontal or at a slight elevation. Phasing network 36 may then be used to vary the phase delay with frequency so that the usual variation in departure angle or elevation angle caused by the earths reflections is eliminated over a wide range of frequencies.

The systems shown in Figs. 1 and 3, may be combined so that the radiation of the horn can be steered to a considerable extent in any direction. Fig. 5 illustrates such an arrangement. The horn 50 is provided with a wave guide 51 which is partitioned by a median metallic wall 52 extending in the vertical or H direction. A pair of probes 53 and 5-4 are positioned similarly to probe 32 and 33 of Fig. 3 and connected through suitable transmission lines 55 and 56 and

pads

57 and 58. Pad 57 is connected through an adjustable phase shift network 59, the input of which is connected to a generator or receiver 61 through another phase shifting network 60. Probes 63 and 64 are similarly connected through

pads

65 and 66 and an adjustable phase shifting network 67 to the generator or receiver. It will be evident from the discussion given above, that phasing

networks

59, 60 and 67 are capable of shifting the radiation beam in either the H plane or the E plane, or both.

I have shown and described several embodiments of my invention in order to illustrate the principles thereof. Many variations of the structures herein shown and described will be apparent to those familiar with this art,

therefore my invention is not to be construed as limited except as defined in the following claims.

What I claim as new and desire to protect by Letters Patent of the United States is:

1. An electrically steerable horn antenna system comprising a rectangular fiaring horn radiator, a rectangular wave guide connected to the small end of the born, a pair of antennas in said wave guide extending in the direction of the electric vector in the wave guide and arranged to excite said wave guide in a TE- mode, said antennas being spaced apart in a direction perpendicular to the axis of the wave guide, radio frequency apparatus, radio frequency transmission means connecting said apparatus to said antennas, and variable means in said transmission means for changing the direction of the major lobe of the radiation pattern, said variable means comprising phase shifting means for varying the relative phase delay between said respective antennas and the radio frequency apparatus.

2. A system according to claim 1, wherein said antennas are linear radiators extending through opposite walls of the wave guide.

3. A system according to claim 2, wherein said wave guide includes a bisecting metallic partition therein extending in the H plane.

4. A system according to claim 1, wherein said antennas are linear radiators extending through the same side wall of the wave guide and are arranged in the same H plane.

5. A system according to claim 4, wherein said wave guide has a height h in the H plane and said antennas are spaced respectively /3 h from the top and the bottom walls of the wave guide.

6. A system according to claim 5, wherein said wave guide includes a bisecting metallic partition extending in the H plane, a second pair of antennas extending into the wave guide through the opposite side wall thereof, each of said second antennas being positioned opposite one of the antennas of the first pair, phase adjusting means connected between said radio apparatus and the second pair of antennas for cooperating with said first mentioned phase shifting means for steering the radiation pattern in either, or both, the E and the H planes.

7. An electrically steerable horn antenna system comprising a pyramidal horn radiator, a rectangular wave guide connected to the small end of the horn, a metallic partition in an H plane bisecting said wave guide, a pair of linear probes in said wave guide extending from opposite side walls thereof in the same E plane, radio frequency apparatus, radio frequency transmission means connecting said apparatus to said probes, and variable means in said transmission means for steering the direction of the major lobe of the radiation pattern in the plane of said probes, said variable means comprising an adjustable delay network for varying the relative phase delay between said respective probes and the radio frequency apparatus.

8. An electrically steerable horn antenna system comprising a pyramidal horn radiator, a rectangular wave guide connected to the small end of the horn, a pair of linear probes in said wave guide extending perpendicularly from one side wall thereof in the same direction in an H plane, radio frequency apparatus, radio frequency transmission means connecting said apparatus to said probes, and adjustable means in said transmission means for steering the direction of the major lobe of the radiation pattern in the plane of said probes, said adjustable means comprising phase shifting means for varying the relative phase delay between said respective probes and the radio frequency apparatus.

9. The method of operating a horn antenna so as to prevent variations in the departure angle of the radiation caused by the earths reflections, comprising the step of mounting the antenna several wave lengths above the earths surface for radiation at said angle and exciting a wave guide connected to the horn in a TB 10 mode and adjusting the relative phase delay in a pair of transmis sion paths connected between radio frequency apparatus and a pair of antenna probes extending into the wave guide in accordance with variations of the frequency of the radio frequency energy so that the departure angle remains nearly constant.

References Cited in the file of this patent UNITED STATES PATENTS 2,245,660 Feldman June 17, 1941 2,464,276 Varian Mar. 15, 1949 2,556,094 Lindenblad June 5, 1951 2,810,908 Crawford Oct. 22, 1957