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 electric field of 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. Moreover, the measured results are in excellent agreement with the simulated data.