MEMS enabled frequency selective surface for 60 GHz applications

A MEMS enabled frequency selective surface is described for 60 GHz applications. The transmission through the FSS can be switched by 30 dB at resonance by switching the MEMS between ON and OFF states. As well as other applications, this FSS can be used as a free-space amplitude shift keying modulator. An FSS model is developed that is based on the rectangular loop aperture geometry. Each unit cell has two MEMS contact type switches across the aperture at an 180 degree interval. Due to the rectangular geometry, the FSS can operate in only one polarization i.e. either TE or TM depending on the orientation of the incident electric field. The bias line of the MEMS switches is placed under the top conductor separated from the substrate by a thin layer of silicon nitride. This helps to simplify the fabrication as only single sided patterning is required. Positive dc bias is provided by biasing the electrode of the MEMS switches when the MEMS cantilever beams are connected to ground through the outer conductor of the FSS structure. Preliminary theoretical results are presented.