Do We Really Need Frequency-Selective Surface and Metasurface Reflectors for Antenna Gain Enhancement, or Are Metallic Reflectors Enough?

Enhancing antenna gain remains a key requirement in modern wireless systems, particularly with the rapid evolution of 5G, emerging 6G networks, satellite links, and high-resolution radar. Recent research trends increasingly rely on frequency-selective surfaces (FSSs) and metasurface-based reflectors, which offer precise electromagnetic wave control, beam shaping, and polarization management. However, these advanced structures often require complex unit-cell optimization, tight fabrication tolerances, and higher implementation cost. This situation raises a practical question: Are such sophisticated reflector surfaces always necessary, or can conventional metallic reflectors still provide competitive gain performance in many scenarios? In this review, I critically compare metallic reflectors, FSS reflectors, and metasurface reflectors in terms of gain enhancement, bandwidth behavior, sidelobe control, polarization response, fabrication complexity, and cost-effectiveness. The analysis reveals that while FSS and metasurfaces enable highly controlled and adaptive radiation characteristics, simple metallic reflectors can achieve comparable gain performance in many broadband and cost-sensitive applications. The review also identifies application domains where advanced reflectors are justified—such as adaptive beamforming, spatial filtering, and reconfigurable intelligent surface (RIS) platforms—and those where metallic reflectors offer a more efficient and accessible solution. This study provides practical design insight to help antenna engineers balance performance, complexity, and implementation cost, demonstrating that high gain does not always require high structural complexity.