Design of a wideband square slot bandpass frequency-selective surface using phase range analysis

This article presents the design of a wideband bandpass frequency-selective surface (FSS). The structure is designed using the analysis of the generalized scattering matrix (GSM)-based transmission phase range. A relationship between the transmission phase range and the bandpass fractional bandwidth (FBW) is developed. The analysis reveals that the FBW of the FSS unit-cell is proportional to the phase range. Based on the interpretation of results, a design curve has been drawn, and using this curve, a simple square slot FSS on a low-cost FR-4 substrate has been fabricated and measured. Using the design curve, a 53% FBW has been predicted. The simulated results show a 52% FBW with the 3.52-GHz center frequency (f_o). The response for the transverse electric (TE) and transverse magnetic (TM) modes has been measured. The structure has a bandpass FBW equal to 50% and 53.3% in TE and TM modes, respectively. The method presented in this article may be used to increase the bandpass response of different FSS topologies.