Antenna-filter-antenna based frequency selective surfaces for quasi-optical applications in Q-band

A new 3-layer antenna-filter-antenna (AFA) elementary cell is proposed for frequency selective surfaces (FSS) in quasi-optical applications, where wideband and low loss characteristics are crucial. The elementary cell is composed of a CPW resonator sandwiched between patch antennas. Finite element method is used for the design and verification of the proposed AFA elementary cell while a free space Gaussian optics measurement system is utilized for S-parameter characterization. The measurement results show a 27.6 % 3-dB (18.5 % 10-dB) bandwidth and a maximum in-band insertion loss of <;0.2 dB for 40.5 GHz.