Bandpass frequency selective surface based on a two-dimensional periodic array of shielded microstrip lines

In this paper, we describe a high performance bandpass FSS that can be realized using a two-dimensional periodic array of shielded microstrip lines. Based on the dispersion diagram of a shielded microstrip line, it is possible to excite a desired number of propagating modes and then control their coupling with air to obtain a required bandpass response. As an example, we design an FSS that contains two transmission zeros, while its thickness is less than λ_c/5, where λ_c is the free space wavelength at the center frequency. An equivalent network of the designed FSS has also been presented. We employ an efficient full-wave mode-matching method to simulate the proposed structure. Simulation results under an oblique incidence predict an excellent angular stability of this 3-D FSS.