A Low-Loss Reconfigurable Plasma Impedance Tuner for Real-Time, Frequency-Agile, High-Power RF Applications

Many frequency bands, previously allocated solely for radar, are being designated for sharing. Future radar transmitters must adaptively share the frequency spectrum with wireless communications, requiring high-power, high-speed reconfigurable circuits to maximize radar detection range upon changes in frequency and antenna impedance. This paper presents an octave (2–4 GHz) S-band reconfigurable impedance tuner with 35 W plasma switches connecting shunt inductors and capacitors to a series feedline. The tuner can be reoptimized to maximize output power in approximately 300 µs upon changes in operating frequency or antenna impedance. The tuner has a much lower average insertion loss (2.5 dB) and comparable optimization times when compared with the previous state-of-the-art octave S-band plasma tuner. The new design significantly reduces loss over its octave tuning range using shunt inductors and capacitors instead of open-circuited stubs.