Pulse-to-Pulse Circuit Reconfiguration in Spectrum Sensing Radar

Because the wireless spectrum is becoming increasingly congested due to re-allocation of radar frequencies for spectrum sharing, radar systems need to be able to adapt and change operating frequency quickly in response to interference. In a cognitive radar capable of spectrum sharing, reconfigurable transmitter circuitry allows the output power to be reoptimized to maximize detection range. Real-time reconfiguration has been accomplished through real-time impedance tuners that have been implemented using a software-defined radio controller with intelligent optimization algorithms. With a new, fast plasma-switch impedance tuner, a complete evaluation of the output power for a single tuner setting can be performed during the on-time of a pulse. We have placed the plasma-switch tuner under control of a spectrum-sharing software-defined radio platform to demonstrate circuit reconfiguration upon changing operating frequency and bandwidth on a pulse-to-pulse basis. The ability to reconfigure the transmitter amplifier load impedance allows the radar to detect targets at greater ranges while maximizing the signal-to-interference-plus-noise ratio by evading potential interference.