Abstract: A dual frequency feed for use with an antenna permits reception of signals in both a low frequency band and a high frequency band and is comprised of a single feed through which both signals are propagated, a high frequency probe which extends concentrically within the throat of the feed for receiving the high frequency signal, a wave guide connected to the throat of the feed including a pair of turnstile junctions with four wave guides interconnecting the turnstile junctions, and a single output port with a polarization rotation device for receiving the low frequency signal. The four interconnecting wave guides may be either co-axial cables or generally rectangular wave guides.

Abstract: A microwave transmit/receive terminal having an antenna and associated feed for receiving vertically and horizontally polarized signals and for transmitting a horizontally polarized signal employs a diplexer to be inserted between the feed and an orthomode coupler. The diplexer is formed of a cylindrical waveguide main body, a first port of which is coupled to the feed for receiving the orthogonally polarized receive signals and for coupling thereto the (horizontally polarized) transmit signal. A second port of the main body is coupled to the orthomode coupler for receiving the horizontally polarized signal to be transmitted and for coupling thereto the vertically polarized receive signals. A rectangular waveguide section is coupled to the cylindrical waveguide main body and forms a third port for coupling the horizontally polarized received signal away from said cylindrical waveguide main body.

Abstract: A five-horn Cassegrain antenna is disclosed comprising a main dish, an up-taper subreflector set on the boresight axis of the main dish, and including a sum horn positioned on the boresight axis between the subreflector and the main dish with four error horns set therearound. The aperture of the sum horn is relatively large to substantially eliminate radiation spillover at the up-taper subreflector. The error horns are positioned around this large aperture sum horn such that the radiation patterns of paired error horns will crossover in their sidelobes. These error horns are provided with a high aspect ratio with the narrow dimension of each error horn being located in the plane of its tracking crossover with the radiation pattern of the other error horn with which it is paired.