Pulsed polarimetric millimeter-wave radars that utilize extended interaction amplifier and oscillator tubes

The University of Massachusetts has developed two high-power portable polarimetric radars operating at 95 and 225 GHz. The 95 GHz polarimeter employs an extended-interaction klystron amplifier capable of 1500 W peak power output. The system is configured to measure the complex scattering matrix of a target by transmitting a pair of orthogonally polarized pulses in rapid succession. A noncoherent 225 GHz polarimetric radar which directly characterizes the target Mueller matrix by transmitting a sequence of six polarization states has also been developed. The 225 GHz system utilizes an extended-interaction klystron oscillator that generates a 60 W peak power pulse. The authors review the design of the 95 and 225 GHz radars, and highlight significant measurements and applications