Design of Frequency Selective Rasorber Applicable to Domestic 5G Communication Environments

In this paper, a frequency-selective rasorber (FSR) with absorptive-transmissive-absorptive (A-T-A) characteristics is proposed for the domestic 5G frequency band that absorbs out-of-band signals. The proposed FSR consists of a lossy frequency-selective surface (FSS) incorporating resistive elements within a square-ring patch configuration, a lossless FSS formed by adding a square patch structure to a lattice structure, and an air layer that provides impedance matching between the two FSS structures. Simulation results show a transmission loss of −1.04 dB at 3.59 GHz and a −3 dB operating bandwidth of 420 MHz (3.44~3.86 GHz). To verify the performance of the proposed structure, a 20×20 array with an overall size of 500×500 mm2 was fabricated, and its actual performance was evaluated using a free-space measurement method. The measured results show a transmission loss of −1.18 dB at 3.64 GHz, and a −3 dB operating bandwidth of 390 MHz (3.43~3.82 GHz) was confirmed.