T/R module for CASA Phase-Tilt Radar Antenna Array

This paper describes the transmit/receive module for the X-band Phase-Tilt array antenna being developed at the Engineering Research Center for the Collaborative Adaptive Sensing of the Atmosphere (CASA). Architecture, fabrication and electrical performance are described. The RF subsystem is designed with commercial-off-the-shelf GaAS MMICs. The design includes a custom PIN diode based diversity switch that provides polarization diversity to the array elements in both transmit and receive channels. The module operates at 9.36 GHz and has a bandwidth of 1.0 GHz. Gain and phase are controlled by a 6-bit digital attenuator and 6-bit digital phase shifter respectively. Commands and RF switching signals are controlled with a FPGA. The T/R modules were fully tested using a measurement station developed specifically for this purpose.