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The design and test results of an improved C-band four-bit PIN-diode phase shifter are described. Exceptional wideband performance is achieved through the use of a novel planar, s t r i e l i n _~y b~~. c u p ! e r t h a t is used in the 90-degree and 180-degee phase b~t s . The measured amplitude and phase flatness versus frequency of these phase bits exceeds the theoretical bandwidth characteristics of a conventional hybrid ring by itself. For BITE implementation, the PIN diodes are mounted to allow bias voltage and current of each diode to be monitored individually.

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Acompacthigh-powerfeedforpowerdistributioninthehorizontalplaneofaC-bandplanar-array antenna is described. A combination of WR159 branch-guide couplers and of airdielectric-striptine powerdividersprovideshighpower-handlingcapacityinthelimitedspaceavailable. Theseries-parallel feed architecture and phase-compensating waveguide sections have a calculated instantaneous signal order to minimize the effect of varying impedances which typically occur in a scanning array bandwidth greater than 200 MHz. Four-port couplers and power dividers are used throughout in antenna.

The design and fabrication of an affordable, all-machined, precision serpentine feed for application to a large S-band planar array antenna is described. By using reduced-height guides, it is possible to include both main and coupled waveguide channels within the periodic array spacing of approximately two inches.