Micromachined W-band polymeric tunable iris filter

A tunable filter working in the W-band spectrum has been successfully demonstrated using a combined plastic molding and electroplating process. The prototype filter architecture has two deformable membranes of 1.6 mm in diameter on top of a WR-10 waveguide based, two-cavity, polymeric iris filter. The membranes can be actively adjusted to deform and alter the cavity geometry concurrently for frequency tuning applications. The tunable filter was simulated using High Frequency Structure Simulator and theoretically analyzed using the perturbation method. Experimentally, a prototype band-pass filter has bandwidth of 4.05 GHz centered at 94.79 GHz and a minimum insertion loss of 2.37 dB with return loss better than 15 dB. As a tunable filter, a total of 2.59 GHz center frequency change has been recorded when the membranes deflected from 50 μm into, to 150 μm out of the waveguide. These results imply that the demonstrated tunable filter could be potentially applicable for waveguide-based mm-wave systems.