Patent ID: 8643560

Claim:
A feed network comprising: a cylindrical common waveguide having an axis and terminating in a common port; an orthomode transducer having a first port for coupling a first linearly polarized mode to the cylindrical common waveguide and a second port for coupling a second linearly polarized mode to the cylindrical common waveguide, the second linearly polarized mode orthogonal to the first linearly polarized mode; and a filter-polarizer element disposed within and rotatable about the axis of the cylindrical common waveguide, the filter-polarizer element further comprising: an elongated hollow dielectric tube coaxial with the cylindrical common waveguide; and a phase shifting element disposed within the dielectric tube, the phase shifting element comprising a rectangular dielectric card, the rectangular dielectric card having a length extending along a length of the dielectric tube, a width extending across an inside diameter of the dielectric tube, and a thickness substantially smaller than the width, wherein: the phase shifting element is perforated by a plurality of openings defining alternating phase shifting regions and open regions, the phase shifting regions are configured to cause, in combination, a predetermined relative phase shift between a first signal and a second signal propagating in the cylindrical common waveguide, and the open regions are configured to suppress propagation of at least one undesired mode in the cylindrical common waveguide.