Integrated W-Band Photoconductive Switches in SIW Technology

A novel approach for the design of millimeterwave (mmWave) substrate-integrated waveguide (SIW) switches is presented. The switch is based on controllable photoconductive elements (PEs), whose conductivity is modulated by a light source. The PE is integrated on the top SIW metal plate and provides either a short-circuit or transmission operation regime, depending on the actuation conditions. Due to the light actuation, the mmWave and dc control circuitry are naturally decoupled, which, in turn, makes the design low-loss and compact as compared to p-i-n diode and integrated circuit-based SIW switches implementations. We demonstrate two examples of SIW photoconductive switches (PSs) at W-band: single-pole single-throw (SPST) and single-pole double-throw (SPDT) PSs. Their operation principle, actuation, and parasitic radiation suppression are discussed. Measurements show the peak insertion loss of 0.9 and 2.2 dB, isolation better than 25 and 30 dB, and -10 dB impedance bandwidth of 21% and 15% for the SPST and SPDT PSs, respectively.