US3068478A

US3068478A - Horn antenna having reduced length

Info

Publication number: US3068478A
Application number: US835666A
Authority: US
Inventors: Boynton G Hagaman
Original assignee: ANTENNA SYSTEMS Inc
Current assignee: ANTENNA SYSTEMS Inc
Priority date: 1959-08-24
Filing date: 1959-08-24
Publication date: 1962-12-11
Anticipated expiration: 1979-12-11

Description

Dec. 11, 1962 B. G. HAGAMAN 3,068,478

HORN ANTENNA HAVING REDUCED LENGTH TZLEILE' v A Tlta/z fu, 32

ATTO R N EYS United States Patent Oil-ice y 3,068,478 Patented Dec. 11, 1962 3 068,478 HORN ANTENNA HVIN G REDUCED LENGTH Boynton G. I-Iagamau, Falls Church, Va., assiguor to Antenna Systems, Inc., Washington, D.C., a corporation of Delaware Filed Aug. 24, 1959, Ser. No. 835,666 Claims. (Cl. 343-756) The present invention relates to electromagnetic horn antennas and particularly to means and methods of reducing the length of horn antennas.

According to the present invention the length of a horn antenna can be reduced considerably. This is accomplished by exciting the horn by an array of radiators disposed in the wave guide connected to the horn so that at a point thereof which would normally be, say, about the middle of the length of the horn, a desirable wave front is produced. Thus, at a point not too far from the aperture of the horn, the wave front near the walls of the horn is not delayed relative to the portion thereof near the middle of the horn, as it would be in a conventional horn antenna. If desired the array of radiators may be energized in phase so that a plain wave front occurs at the point of excitation. Thus, the wave will arrive at the aperture at or nearly in phase, thereby enabling the antenna to maintain a high radiation eiliciency.

An object of the present invention is to accomplish this result without impairing or obstructing the transmission of waves through the horn.

Other objects and advantages of the invention will become apparent and the invention itself will be fully understood from the following description and the drawing, in which:

FIG. 1 is a front view looking into the aperture of a horn antenna according to the invention;

FIG. 2 is a side view of the antenna shown in FIG. l; and

FIG. 3 is a side view of another embodiment of my invention.

FIGS. 1 and 2 show the invention applied to a horn antenna of the type disclosed in my copending application Serial No. 791,248, now Patent No. 2,992,429. The antenna has a rectangular tapered aperture with the diagonals of the rectangular aperture extending vertically and horizontally. It will be assumed that the antenna is to be used for receiving or transmitting horizontally polarized waves although it will be readily understood that the invention can be used for vertically polarized waves merely by changing its orientation by 90. The horn is formed of eight triangular sides 11-18 which dene a rectangular or square aperture 20. It will be understood that other kinds of tapered horns may be used, several types of which are disclosed in my prior Patent 2,851,686. At the small end 21 of the horn there is connected a rectangular wave guide 22. The wave guide is divided into a plurality of cells by metallic partitions 24 and 26. In each cell 25 a horizontal linear radiator 28 is mounted. Radiators 28 may be any suitable type of antennas such as, for example, linear probes mounted on, but insulated from the metallic partitions 24 and the end wall 30 of the wave guide. It will be evident that other types of well-known linear radiators such as dipoles, for example, could be used. Radiators 28 are connected by transmission lines 30 to suitable radio receiving or transmitting equipment 32. The transmission lines 30 conveniently can be coaxial transmission lines. The transmission lines are preferably arranged so that radiators 28 are connected to the translating apparatus 32 in the same phase. Thus, if the translating apparatus 32 is a transmitter, the radiators 28 will be excited in phase and produce a plane wave front in the plane of the radiators. This plane wave is then propagated through wave guide 22 and the horn to the radiating aperture 20. Since the horn is comparatively short, the `amount of dephasing which occurs in the travel of the wave to the aperture is relatively small, so that even a short horn lengtha'nd large llare angle does not cause an excessive phase diierence of the energy at the radiating aperture 20. As a result, the operating eiciency and the directivity of the horn remains large despite the short length of the horn antenna.

FIG. 3 shows an arrangement similar to that of FIGS. 1 and 2 except that the horn 40 is of a conventional flared rectangular type, rather than the tapered aperture type shown in FIGS. l and 2.

If desired, the radiators 28 can be energized, as disclosed in my copending application, Serial No. 835,730, led August 24, 1959. When so energized, the radiators in the cells at the middle of the wave guide are excited with waves having a phase delay relative to the wave supplied to the radiators near the end walls of the wave guide. In this way, the longer time of travel of the wave from the outermost radiators may be compensated. Such phase delay may be provided by suitable delay lines or delay devices or by additional length of the transmission t lines connected to the radiators in the middle cells of the wave guide.

Many modications and variations of the invention herein illustrated will be apparent to those skilled in the art and therefore the invention is not to be construed as limited except as defined in the following claims.

What is claimed is:

1. A shortened horn antenna having a plurality of outwardly flared peripheral walls joined to one another along their longitudinal edges and dening a single radiating f aperture, a rectangular wave guide connected directly to all said walls at the small end of the horn, intersecting metallic partitions in said wave guide extending thereacross in a direction substantially parallel to the axis of the horn and dividing the wave guide into a plurality of cells, a two-dimensional array of aligned radiators mounted in said cells of the wave guide, and radio Wave transmission means connected to all of said radiators.

2. A shortened horn antenna comprising a flared electromagnetic horn having a single radiating aperature at one end and an opening at the other end, a rectangular wave guide connected to the other end of the horn, metallic, mutually perpendicular partitions in said wave guide extending thereacross in a direction substantially parallel to the axis of the horn and dividing the wave guide into a rectangular array of cells, a two-dimensional rectangular array of linear parallel radiators mounted in said cells of the wave guide and transmission line means connected to all of said radiators.

3. A shortened horn antenna comprising a flared horn, ya wave guide connected to .the small end of the horn, intersecting metallic partitions wholly within said wave guide extending parallel to the axis of the horn and dividing the wave guide into a plurality of cells, a two-dimensional array of radiators mounted in said cells of the wave guide, and transmission means connected to all of said radiators for energizing a plurality of said radiators out of phase with other radiators.

4. A shortened horn antenna comprising a wave guide connected to the small end of the horn, intersecting metallic partitions in said wave guide extending thereacross parallel to the axis of the horn and dividing the wave guide into a plurality of cells, a two-dimensional array of parallel linear polarization radiators mounted in said cells of the wave guide, and wave translation means connected to all of said radiators.

5. A shortened horn antenna comprising a flared horn having plane walls forming a single aperture having a maximum width at the middle thereof and tapering to a-minimum value at the ends thereof, a rectangular wave guide connected to the small end of the horn, metallic, mutually perpendicular partitions in said wave guide extending thereacross parallel to the axis of the horn and dividing the wave guide into a rectangular array of cells, a 4two-dimensional rectangular array of linear parallel radiators mounted in said cells of the wave guide and transmission line means connected to al1 of said radiators for energizing said radiators with radio waves having the same phase.

References Cited in the tile of this patent UNITED STATES PATENTS