The Open Cassegrain Antenna: Part II. Structural and Mechanical Evaluation

Various mechanical features of the present concept for an open cassegrain antenna are discussed below. The present concept is based on preliminary analysis of some of the problems posed by the unusual geometry and expected applications of the structure. These problems include the inherent asymmetry of the configuration, the need for rigid "external" supports for the subreflector, the design of the slant bearing and slant axis drives, and the desire to terminate the feed horn adjacent to the azimuth axis. The last requirement permits the horn to connect to the stationary communication equipment through a very short length of circular waveguide and rotary joint concentric with the azimuth axis. An aperture diameter of 56' was somewhat arbitrarily selected for this design study. An open cassegrain of that size would meet typical requirements for major satellite communication system earth stations. Fig. 1 is a line drawing of the basic structural configuration that 1301 t P4BARDI ninAI cc o IC