Design and Analysis of X/Ka-band Irregular Inductive Frequency Selective Surface with Dual Transmission Poles for Beam-Waveguide Antenna

The paper presents the results of the design and simulation of the irregular inductive frequency-selective surface (FSS) for dichroic mirror in the beam-waveguide (BWG) feed in X/Ka-band. Traditional electromagnetic (EM) analyses based on a uniform plane wave incidence were augmented by advanced numerical techniques to investigate the impact of the dichroic mirror on the overall antenna performance. The irregularity of the proposed FSS is introduced in varying aperture (unit cell) dimensions in one of the coordinates to minimize the energy losses at high frequencies. The optimal shape of a periodic cell is determined and characterized by the presence in the frequency response dual transmission poles in uplink/downlink bands, corresponding to the frequencies of reception and transmission in the Ka-band. Due to the varying cell grid structure the averaged losses over the entire range of incidence angles from 16° to 44° with an amplitude decay of the real source to the FSS edges were 0.06 dB, so this is acceptable attenuation for such structures.