A Compact Single Layer Dual-Bandstop Frequency Selective Surface for WLAN Applications

In this paper, the design of a compact single-layer frequency-selective surface (FSS) is discussed. The unit cell of this proposed FSS structure is composed of a modified interconnected open square-headed dumbbell-shaped (OSHD) structure located at the four corners. This unique configuration imparts dual-bandstop characteristics to the FSS, resulting in stopband behavior spanning bandwidths of 230 MHz and 300 MHz, with resonant frequencies of 2.4 GHz and 5.0 GHz, respectively. To illustrate the bandstop behavior, surface current distribution and electric field variations are discussed. The unit-cell size of this FSS is 0.12λ0, where λ0 represents the free-space wavelength at the lower resonant frequency. Notably, the proposed FSS exhibits polarization independence and maintains stable performance upto 60% for both Transverse Electric (TE) and Transverse Magnetic (TM) polarizations. The design and analysis of this structure were carried out using the ANSYS HFSS software.