Ultra-Fast Low-Loss SPST Switch Using Planar GaAs Diodes for $G$-Band Radar Receiver Protection

In this article, we report on the development of a high-performance, tunable, solid-state, single-pole-single-throw (SPST) switch operating in $G$-band for radar applications. Future space-borne, high-power $G$-band radars may require an SPST switch for receiver protection. We explore a novel solid-state switching architecture based on planar GaAs Schottky diodes. The switch, optimized for operation from 158 to 175 GHz, achieves high isolation by absorbing, reflecting, and frequency multiplying the input power to the second harmonic. A first demonstrator is characterized with an on-state insertion loss <0.86 dB and return loss >20 dB at 0 dBm input power. The off-state isolation exceeds 43 dB at 0 dBm input power and remains above 30 dB at +17 dBm input power. Depending on the required isolation, the switch is tunable with an instantaneous bandwidth ranging from 300 MHz (for 30 dB isolation) to 13 GHz (for 15 dB isolation). The switch is successfully demonstrated to operate at an ultra-fast 4 MHz switching rate with a switching speed of a few nanoseconds.