Wideband, Electronically Reconfigurable, 0°/90° Phase Shifter for High-Power Microwave Phased Arrays

We present the design and experimental characterization of a wideband, high-power capable, electronically controllable, 0°/90° phase shifter. The device is a type of microstrip Schiffman phase shifter implemented inside a double-ridge (DR) waveguide, incorporating custom-designed DR waveguide-to-microstrip transition (DRWM) sections. The phase shifter achieves two electronically switchable phase shift states by employing two high-power-capable p-i-n diodes over a wide bandwidth exceeding 55% (1.76:1). To achieve high-power-handling capability, the microstrip phase shifter Section was implemented on an aluminum nitride (AlN) ceramic substrate that offers high thermal conductivity and high-temperature tolerance. The DR waveguide and transition sections are thermally connected to the microstrip phase shifter Section and act as efficient heat sinks when the device is operated under high-average power levels. Our simulations indicate that this 1-bit phase shifter can provide 0°/90° phase shifts over a wide bandwidth in the 6.6–11.5-GHz range with a phase error of less than ±20° and an insertion loss of less than 1.5 dB. We fabricated a prototype of the phase shifter and experimentally characterized it at both low- and high-power levels. The measurement results confirmed the simulations and demonstrated the wideband and high-power-handling capabilities of the device. High-power continuous-wave (CW) experiments were conducted across the entire frequency band and demonstrated that the CW power-handling capability of the device exceeds 30 W. Pulsed high-power experiments at 9.382 GHz established that the peak power-handling capability of the device exceeds 1.1 kW for a pulsewidth of
$1~\mu \text{s}$
.