Characteristics and design of the LAR offset system with feed-reflector

A novel approach for analyzing the quasi-optical offset large adaptive reflector (LAR) Cassegrain system is described. In this system, a feed-reflector is used to illuminate a reconformable hyperboloid subreflector with 5-10 m diameter, located 500 m above the ground. An exact equation for the offset LAR surface is given. To scan the beam up to 60° which is one of the LAR requirements, the concept of the dual offset LAR with feed-reflector is introduced. In this design, the cross polarization is eliminated by a proper orientation of the subreflector. The parameters of the configuration are obtained by utilizing generalized Gauss-Laguerre beam modes and matrix representation of the beam mode transformation factor. The blockage effect due to the feed-reflector is totally removed.