Reconfigurable and Adaptive Radar Amplifiers for Spectrum Sharing in Cognitive Radar

The increased use of the wireless spectrum for broadband applications has necessitated a new approach to radar transmission. Future radar systems will be required to adjust operating frequency in real time to avoid interference from other wireless devices operating in the same band. This paper describes the use of a 90 W tunable power-amplifier matching circuit to reconfigure a power amplifier for high power-added efficiency and spectral compliance at multiple frequencies within the S-band. To reconfigure the amplifier in real-time spectrum sharing scenarios, a modified gradient search algorithm is employed to tune the amplifier based on measured data. A look-up table allows previous optimum tuner settings to be stored after the first reconfiguration at each operating frequency, allowing faster optimizations upon re-visits to each frequency. Next research steps are discussed; including the streamlining of system timing, operating the search algorithm under control of spectral prediction and decision-making processes and analyzing the effect of impedance tuning on range and Doppler detection.