A 10-183 GHz common aperture antenna with a quasioptical frequencymultiplexer

摘要

A multifrequency coboresighted antenna would be cost effectivenbecause many wavelengths utilizing different receiver technologies wouldnbe observed with one instrument. Because the size of quasiopticalncomponents is determined by wavelength, filtering the lowest frequenciesnfrom the beam first allows the system to be compact. Two calibrationnschemes are then possible, a conventional method for the microwavenfrequencies and a quasioptical method for the shorter wavelengths. Thenbrassboard instrument described in this paper consists of an offsetnCassegrain antenna with a 60×65 cm aperture and a quasiopticalnfrequency multiplexer with 7 distinct channels at 10, 18, 22, 37, 50-58,n90, and 183 GHz. The frequency selective surfaces (FSS) include 1 dualnfrequency bandpass filter and 4 perforated ellipsoidal mirrors, whichnare high pass filters in the band of interest and focusing elementsnbelow the cutoff frequency. With the main reflector and subreflectornthis system is contained in a volume 175×155×68.3 cm. Thenmultiplexer by itself has dimensions of 100×155×32 cm, whichninclude all feeds, lenses, and fss components. In each band the power isncoupled to waveguide via a scalar feed and a lens. In all channels thenauthors measured beam patterns, gain, cross polarization, return loss,nand interchannel isolation