Design of an absorption–transmission-integrated frequency selective surface using a waveguide array

A hybrid frequency selective surface (FSS) with low-frequency absorption and high-frequency transmission is designed and demonstrated experimentally. The waveguide array with the spatial filtering characteristics of low-frequency reflection and high-frequency transmission is firstly proposed and the resistor-loaded loop array is then introduced on the top layer. Since the metal-like behavior of the waveguide array at low frequencies, the hybrid FSS can achieve strong absorption, while the transmission at high frequencies can be kept all the same. Simulated results show that the proposed hybrid structure can achieve broadband absorption with the efficiency more than 90% in the frequency range of 7.7-12.4 GHz and effective transmittance more than 80% from 16.5 to 18.0 GHz. The maximum transmittance of 89% can be gained at 17.4 GHz. Finally, the experimental measurement has also been performed to provide a good demonstration.