Micromachined Waveguide-Integrated Sub-THz Crossover Switch

This paper presents the design, fabrication, and characterization of a novel crossover switch implemented by silicon micromachining. The switch consists of two single-pole-single-throw switches, two hybrid couplers, and four E-plane transitions to standard WR-3.4 waveguide, with a total footprint of 5.6mm×5mm×1.2mm. The switching is performed based on short-circuiting the dominant mode of the rectangular waveguide by two sets of microelectromechanically reconfigurable switching surfaces (MEMS-RSs) controlled by electrostatic actuators. It has two input ports and two output ports, which are completely symmetric regarding input-output signal paths, making the designed switch well-suited for adding redundancy to RF systems. The measured isolation and insertion loss of better than 29.3 and between 0.9-1.4 dB and better than 29 and between 0.8-1.3 dB are achieved in the crossover (propagating) and straight (reflecting) states, respectively, with the return loss of better than 14 and 13.6 dB, for these states in the 220-260 GHz frequency band.