500-600 GHz RF MEMS based tunable stub integrated in micromachined rectangular waveguide

This paper presents a 500-600 GHz switchable Eplane waveguide stub tuned MEMS device. It is the first ever RF MEMS component reported to be operating above 220 GHz. The micromachined E-plane stub can be blocked/unblocked from the micromachined waveguide by using a MEMS-reconfigurable surface. The surface is designed so that in the blocking state it is in the H-plane and comprises the roof of the main waveguide, whereas in the non-blocking state it comprises a transmissive Eplane surface for the stub. The measurement results of the first prototypes show a return loss better than 15 dB from 500-600 GHz. The insertion loss is better than 3 dB up to 550 GHz, and better than 4 dB up to 600 GHz. The switchable stub can be utilized as a basic reconfigurable device for tuning/matching of waveguide components under operation; the implemented prototype switchable stub achieves a (measured) tuning of 2.5° at 500 GHz, with a change in S21 better than 0.15 dB for the whole band. The paper further shows that the reconfigurable stub can also be operated in analog tuning mode. This paper also demonstrates that MEMS-reconfigurable E-plane surfaces can be designed and operated deep into the submillimeter-wave frequency range.