Design and Experimental Validation of a Compact FSS-Based Absorber for Sub-6 GHz 5G Applications

Abstract

In this study, a compact and cost-effective Frequency Selective Surface (FSS) unit cell absorber is proposed to mitigate electromagnetic interference in the sub-6 GHz 5G bands, specifically targeting the n77 (3.3-4.2 GHz), n78 (3.3-3.8 GHz), and n79 (4.4-5.0 GHz) frequency ranges. The absorber structure, fabricated on an FR-4 substrate, was designed through a systematic geometric optimization of patch dimensions and substrate thickness to enhance absorption performance via inductive-capacitive resonance tuning. Simulation and experimental results show strong agreement, with a maximum absorption rate of 98% at 4.2 GHz and over 80% absorption between 3.5 GHz and 4.7 GHz. The structure also demonstrates robust angular stability up to 60 degrees, making it suitable for practical applications requiring directional reliability. Compared to existing designs, the proposed FSS absorber offers superior absorption efficiency, simpler fabrication, and enhanced angular resilience. This work contributes a practical and validated solution for targeted EMI suppression in 5G-enabled electronic systems.