Communications: radio wave antennas – Antennas – Wave guide type
Patent
1987-07-20
1989-10-10
Hille, Rolf
Communications: radio wave antennas
Antennas
Wave guide type
343761, 343762, H01Q 1306
Patent
active
048735345
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATION(S)
This U.S. application stems from PCT International Application No. PCT/EP86/00661 filed Nov. 17, 1986, now No. WO8703143, May 21, 198
BACKGROUND AND SUMMARY OF THE INVENTION
The invention is related to a horn for the primary focus illumination of a reflector antenna with a horn flange which is arranged at the output end of a tubular circular waveguide and which widens in a funnel-shaped manner from the throat lying on this waveguide and which has on its inner funnel side grooves oriented in parallel with the axis of the input waveguide.
For such a known horn (as in German published patent application No. DE-OS 3144 319) in which the input waveguide ends precisely with the horn flange throat, by the grooves arranged in parallel to the axis and around the feeding waveguide, a structure is proposed to enable a very precise production of the grooves.
Specially, by such an accurate dimensioning a rather high suppression of the cross polarization is obtained. This known feed horn is specially designed in order to produce a radiation pattern with as low as possible cross polar sidelobes, whereas the aperture illumination or the covering of the reflector antenna to be fed by this horn is less important.
This invention is based on the task of improving the illumination of deep reflector antennas or mirrors, specially for f/D ratios<0.35, where f corresponds to the focal length and D to the aperture diameter of the reflector, in such a manner that under conservation of the least possible cross polarization a high aperture efficiency combined with a high spill over efficiency and a high side lobe suppression is obtained.
This task is by this invention solved by choice of the half opening angle .theta..sub.o of the flange enclosed between the waveguide axis and the inner envelope of the horn grooves to range in the region 70.degree.<.theta..sub.o< 80.degree. and by a forward offset of the TE.sub.11 mode circular waveguide aperture with respect to the horn throat, where this offset of the waveguide is adjusted to obtain the optimal angular width of the horn pattern suitable to the f/D ratio of the reflector.
Ideally, the illumination of covering of the reflector antenna should consist of a constant illumination power across the whole reflector aperture and a step to zero at the reflector rim. This would require a conical-formed field strength (power) characteristics of the feed horn, which has constant field strength inside the opening angle of the reflector. Unfortunately, this ideal case cannot be realized and the uniformity of the illumination especially for deep reflectors is more and more difficult to attain. On the other hand, deep reflectors with f/D<0.35 are of increasing interest, because the horn, being the feed, is more shielded against ground radiation producing additional thermal noise than in shallow reflectors. But it could surprisingly be shown by the invention that appropriate dimensioning of the horn flange opening angle and a suitable "matched" offset of the waveguide against the horn flange throat leads to extraordinary advantageous illuminations e.g. high aperture efficiencies between 50 and 60.degree./o and and a very high spillover efficiency (spillover about 2.degree./o) and a low sidelobe level of about -25 dB (compared against main lobe level). As, further, the cross polarization is considerably suppressed, i.e. the horn radiation characteristic practically shows high cylindrical symmetry, this invented feed is especially useful for circular polarized waves as are e.g. radiated by transmitters of direct TV satellites. The definition of the above mentioned parameters such as: aperture efficiency, spillover efficiency or sidelobe level are in correspondence with common international standards of antenna engineering as e.g. contained in JOHNSON, R. C., JASIK, H. Antenna Engineering Handbook, McGraw Hill, New York 1984, pages 1-5 to 1-7 or RUDGE, A. W., MILNE, K., OLIVER A. D.,KNIGHT,P.: The Handbok of Antenna Design, Peregrinus, London 198
REFERENCES:
Neelakantaswamy et al., "Open-Ended . . . Applicator", IEEE Trans. on Microwave Theory and Tech., vol. MTT-30, Nov. 1982, vol. 11, pp. 2005-2008.
Bahn et al, "Study of Control of Beamwidth of Radiation Pattern of a Waveguide Using Inclined Slotted Flanges", IEE Trans. on Antennas and Propagation, vol. AP-26, No. 3, May 1978, pp. 447-450.
Wohlleben et al, "Primarfokus-Erreger mit geringem Ruckstreuquerschnitt fur Parabolreflektoren", NTG-Fachberichte, Band 57, Vortrage der NTG-Fachtagung, 8 bis 11, Mar. 1977, VDE-Verlag, Berlin, pp. 81-85.
Neelakantaswamy et al, "Circular Waveguide Aperture with a Curved Corrugated Disk as a Primary Feed", G-AP International Symposium, Session 33-Antenna Design, Aug. 1973, Boulder, Colo., pp. 228-231.
Mutschlechner Johann
Wohlleben Rudolf
Hille Rolf
Wimer Michael C.
LandOfFree
Hybrid mode feed horn having funnel-shaped horn flange with groo does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Hybrid mode feed horn having funnel-shaped horn flange with groo, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hybrid mode feed horn having funnel-shaped horn flange with groo will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1960211