MEMS-reconfigurable wavguide iris for switchable V-band cavity resonators

This paper presents for the first time a novel MEMS-reconfigurable inductive iris based on a 30-μm thick reconfigurable transmissive surface and reports on its application to create a switchable cavity resonator in a WR-12 rectangular waveguide (60-90 GHz). The reconfigurable surface incorporates 252 simultaneously switched contact points for activating (ON state) and deactivating (OFF state) the inductive iris by a 24 μm lateral displacement of two sets of distributed vertical cantilevers. In the ON state, these contact points are short-circuiting the electric field lines of the TE₁₀ waveguide mode on the cross-sectional areas of a symmetric inductive waveguide iris, and are not interfering with the wave propagation in the OFF state. Thus, this novel concept allows for completely switching the inductive iris ON or OFF. The inductive iris has an insertion loss of better than 1.0 dB in the OFF state, of which 0.8 dB is attributed to the measurement setup alone. In the ON state the measured performance of the switchable iris is in good agreement with the simulation results. Furthermore, a novel, switchable cavity resonator was implemented based on such a MEMS-reconfigurable iris, and was characterized to a Q-factor of 186.13 at the resonance frequency of 68.87 GHz with the iris switched ON, and an OFF-state insertion loss of less than 2 dB (including the measurement setup) without any resonance, which is for the first time reported in this paper.