Design of a Circular Ring Frequency Selective Surface at Tri-band

This paper presents a first design of a circular ring frequency selective surface (FSS) with reflecting 140 GHz microwave signal (D-band) while transmitting through Q-band (33-50 GHz) and V-band (50-75 GHz) signals, which is used in a microwave system. Relationship between the size of the ring inner diameter and the resonance frequency of the FSS, and the influence of the microwave incident angle on the transmission loss at the resonance frequency (140 GHz) and the passbands (33-75 GHz), are surveyed. Result shows that the resonance frequency decreases with the ring inner diameter increases, which is consistent with the theoretical calculation results. Moreover, the maximum transmission losses at different resonance frequencies are all below −16 dB. For the candidate size, the transmission losses at the resonance frequency and the passbands are about −25 dB and −0.1 dB, and the deviation of the incident angle is acceptable within 8°.