A beam switching Cassegrain antenna configuration was developed for the purpose of making radioastronomical measurements at a wavelength of 3.33 mm. The subreflector periodically switches the antenna beam between the astronomical source and the adjacent sky reference position. The tilting subdish system is used in conjunction with a synchronous detection radiometer, and a complete description of both the rf and electronic systems is given. A discussion of the mechanical and electronic considerations associated with the development of this particular subdish system is made; and a discussion of low frequency switching problems in general is carried out, based upon a series of radiometer noise and gain change measurements made as a function of subdish switching frequency. A method of signal calibration is discussed, with primary emphasis on radioastronomical applications. The use of the tilting subdish system in the investigation of lunar temperature changes during a total lunar eclipse indicates that the system can be used for sensitive radioastronomical measurements.

Radiometric observations of moon during total lunar eclipse at 3.33 mm, noting decrease in equivalent black body disk temperature

Determination of the phase center of the field scattered from the tilted hyperboloidal subreflector in an asymmetric Cassegrainian antenna system is carried out using several techniques. The caustic curves associated with the virtual reflected rays in the asymmetric system are determined from a differential-geometry analysis of the problem. A geometrical-optics analysis is carried out to determine...

Instrumentation and antenna development, solar observations, and lunation observations in study of millimeter wave radiometry for radio astronomy