Compact AMC reflector for sub-6 GHz 5G applications: design and experimental validation

Abstract This paper presents a compact artificial magnetic conductor (AMC) reflector integrated with a planar antenna for upper sub-6 GHz wireless communication applications. The proposed radiator is designed with dimensions of 14 × 13 mm on an FR4 substrate with a dielectric constant of ε r = 4.3 and a thickness of 1.56 mm, providing a compact structure suitable for integration into space constrained wireless terminals. To address the inherently low gain and pronounced backward radiation associated with electrically small antennas, a compact AMC reflector composed of 20 × 20 mm unit cells is introduced. The AMC surface is implemented in a 2 × 2 array, resulting in an overall panel size of 42 mm × 42 mm. Experimental results demonstrate that the AMC-backed antenna maintains an impedance bandwidth and operating range comparable to those of the isolated radiator, while achieving a clear enhancement in forward radiation performance. The inclusion of the AMC enhances the maximum antenna gain by approximately 5 dB across the operating band. With its low profile, compact dimensions, and fully FR4-based realization, the proposed AMC-backed antenna represents a candidate for space-limited wireless communication systems, including 5G terminal devices, customer-premises equipment (CPE), and IoT gateways.