US 2920322 A
Description (OCR text may contain errors)
Jan. 5, 1960 BQP. BROWN, JR
ANTENNA SYSTEM Filed Aug. 28, 1956 Finn :1.
INVENTOR. BU/EW/YPEEGM/V (f?- BY m ia 4% 3 JI'I'OKMSYS 2,920,322 Patented Jan. 5, 1960 ANTENNA SYSTEM Burton P. Brown, Jr., Baldwiusville, N.Y., assignor to the United States of America as represented by the Secretary of the Air Force Application August 28, 1956, Serial No. 606,783 2 Claims. (Cl. 343-776) This invention relates to an antenna system and is particularly concerned with improved methods and means for feeding a transmitting surface in such a system.
In the development of certain high frequency radio devices, such as height finding radar systems, the prior art has found it desirable to employ an antenna system which will produce a number of closely spaced, overlapping, pencil beams arranged along a vertical line. in such systems, a common method of producing such a stack of antenna beams is to employ either a reflecting paraboloidal surface or lens system illuminated from a stack of small electromagnetic horns positioned along a vertical line with their outer edges adjacent to one another. However, the design of the horn arrangement presents a problem. As is well known, the angle of flare at the mouth of a horn is determined by the wavelength of the signal fed therethrough. The difficulty arises when, with a chosen wavelength, the length of each horn and the distance between horn centers must be selected to produce optimum results. If the horns are made sufiiciently long to provide a radiation pattern which will properly illuminate the reflector or lens, the spaces be tween horn centers is so great that the beams, individually or collectively, are not arranged as desired. Conversely, if the horns are spaced to give this desired beam pattern, the physical size of such horns is limited to the extent that the beams are so broad as to not adequately illuminate the reflector or lens. The invention hereinafter described solves this problem by providing a means for maintaining the required close spacing between adjacent horn centers while permitting the physical size of the individual horns to increase to the proper value necessary to satisfactorily illuminate the main reflecting surface or lens; the principle involved being that of employing a series of overlapping electromagnetic horns.
Accordingly, it is a primary object of my invention to provide new and improved methods and means for feeding an antenna system.
Another object of my invention is to provide a means for stacking antenna horns in such a manner as to provide a proper radiation pattern and still maintain close horn spacing.
The above and still further objects, advantages and features of the invention will become apparent upon consideration of the following detailed description of a single embodiment thereof, especially when taken in conjunction with the accompanying drawings, wherein:
Figure 1 is a side view of a single electromagnetic horn constructed in accordance with my invention;
Figure 2 is an end elevational view of a pair of such horns preparatory to their being interleaved; and
Figure 3 is an elevation of a stack of interleaved horns arranged adjacent a parabolic reflector.
Turning now to the drawings in which like characters of reference indicate like parts, an individual electromagnetic horn is shown generally at 10. The horn comprises an elongated hollow neck 12 and a throat portion 14. The latter is flared outwardly from the neck 12 along an axis x. Extending from said throat portion at spaced points along said x axis are a plurality of horn mouths. Those located at opposite ends of the throat 12 are shown at 16, while the intermediate months are shown at 18. Each of said months is flared outwardly along an axis y, and those portions 20 of the throat which lie between horn months are closed by any suitable means. The mouths 16 and 18 are evenly spaced across said throat, and thus providing in effect an alternatingsurface at the end of the horn 10.
In Figure 2, the mouthed end of the horn 10 is positioned adjacent the mouthed end of a similar horn 22. The difference between the horns 10 and 22 lies in the number of mouths and their location. On the latter, a pair of end horns 24 are set in from the ends of the throat along the x axis. The inset distance is substantially equal to the thickness of one of the mouths. The remaining mouths 26 on horn 22 are located in spaced relationship intermediate the end mouths 24 as on the born 10 thereby presenting another alternating surface.
In assembling a stack of electromagnetic horns opposite a reflector or lens 28, as shown in Figure 3, the two types of horns described above will be complementary as to respective mouths and spaces. A horn 10 and a horn 22 will be relatively moved toward each other along their y axes. An end mouth 24 on the horn 22 will slide into the space between an end mouth 16 on the horn 10 and the next intermediate mouth 18. The other mouths and spaces on said horns interlace at the same time in the same manner. A second horn 22 is then interlaced on the opposite side of said horn 10 until the outer edges of its mouths contact similar edges on the first born 22 as seen at 30. By following this procedure of using alternate types for adjacent horns, any desired number of horns may be stacked in place to illuminate the reflector or lens.
When the horns are so arranged, it will be apparent that the spacing between their centers has been greatly reduced. At the same time the physical size limits on such horns have been all but eliminated as a vital factor.
It is to be understood that the above-described arrangement is merely illustrative of the applications of the principles of my invention. Numerous other arrangements may be devised by those skilled in the art without depart ing from the spirit and scope of the invention. 1
What is claimed is:
1. An antenna feed system comprising a series of flared electromagnetic horns, alternate ones of said horns each having a plurality of spaced mouths extending from a throat, spaces between such mouths being closed at the throat end, and the others of said series of horns each being similarly formed, the spaces and months in said latter horns being arranged complementarily to those in the former horns whereby such horns are interleaved to reduce distance between their centers While avoiding limiting their physical size.
2. An arrangement for feeding electromagnetic waves to a transmitting surface comprising at least three aligned hornmeans each having spaced mouths flaring outwardly from one end thereof, said mouths and the spaces therebetween being complementary on adjacent horns whereby such horns assembled with their mouths and spaces overlapping in an alternating pattern.
References Cited in the file of this patent UNITED STATES PATENTS Bohm July 9, 1940