Sub-mm Wave Micromachined Free-Standing Frequency
Selective Surfaces
Norman Grant
The spectral transmittance of a frequency selective surface (FSS),which consists of two freestanding arrays of short-circuited nested annular slots, is presented.
The FSS was designed to provide a minimum of 20 dB isolation between the frequency
bands 316.5–325.5and 349.5–358.5 GHz when the filter operates in the TE and TM plane sat
45_ incidence.
Experimental results, which are in close agreement with the computed transmission
coefficients, show that the maximum insertion loss is 0.9 dB, and the minimum cross-polar
discrimination is at least21 dB in the passbands.
The FSS yields virtually identical spectral responses in the two polarisation planes over the
frequency range 315–359 GHz.