Frequency selective reflector system

Abstract

A dual- band Cassegrain antenna system operable at any polarization is described wherein the hyperbolic subreflector is made to reflect signals at a first band of frequencies and to transmit or pass signals at a second lower band of frequencies. The hyperbolic subreflector according to one embodiment is a square grid mesh with conductive rings centered along the connecting legs of the square grid mesh. The rings are approximately one-third wavelength in diameter at the first band of frequencies and act capacitively at the second lower band of frequencies. The inductive reactance provided by the conductive connecting legs of the grid mesh together with the capacitive reactance provided by the rings at the lower band of frequencies causes the subreflector to transmit signals at the second lower band of frequencies.