Modifications of feed systems for frequency reuse

Feasibility and problems are discussed in relation to conversion of feed systems of existing downlink stations for spectrum reuse operations. Available hardware and likely costs are considered. 35-40 dB polarization isolation is shown to be feasible with or without monopulse tracking couplers. Circuitry for converted feeds, basic feeds, and tracking circuits is displayed. Rotation of the polarization ellipse, axial ratio control for flexible polarization adaptation, steptrack and autotrack circuits, and requirements imposed on feed modification are discussed.