Analysis and Design of Elementary Blinders for Large Horn Reflector Antennas

In recent years, demands have been made to improve the sidelobe performance of the Bell System horn reflector antenna. One demand is related to the Metropolitan Junction Concept* for radio relay route planning. This concept was initiated in the mid 1960's and resulted in narrower angles between radio relay routes converging on a junction point. Generally, increased service demands also added to route congestion and placed more stringent requirements on the antenna performance. A combined experimental and theoretical program was begun with the expressed purpose of reducing certain high sidelobes. * In the Metropolitan Junction Concept, only radio relay routes terminating in a large city are brought into the city. All other routes bypass the city around a ring of stations about 20 miles out. This is contrary to the practice prior to the 1960's. 2979 2980 T H E BELL SYSTEM TECHNICAL JOURNAL, NOVEMBER 1971 A previous paper 1 discussed improvements in the transverse-plane radiation levels for vertical (longitudinal) polarization (VP). This present paper is addressed to transverse-plane radiation for horizontal (transverse) polarization (HP).* The horn reflector antenna 2 is a combination of a square electromagnetic horn and a reflector which is a sector of a paraboloid of revolution. A side view and front plane view of the antenna are illustrated in Fig. 1. The results given in this paper refer to the Bell System horn reflector antenna which has the following aperture dimensions: Flare half angle Front tilt angle Aperture side edge length Average aperture width a = /3 = 2.59 2.59 14.5 degrees 14.5 degrees meters meters.