Magneto-electric Uniaxial Metamaterials as Wide-angle, Polarization-insensitive Matching Layers

Abstract

Antireflection or impedance matching is a topic that has been extensively researched by the optical and microwave communities over the past century and until today. However, due to the diverging wave impedances of TE (s) and TM (p) polarizations with increasing incident angle, it is impossible to achieve perfect matching simultaneously for both polarizations at an oblique incident angle with a single conventional matching layer. In this paper, we show that simultaneous perfecting matching of an arbitrary substrate at an arbitrary incident angle from air is possible with a single uniaxial metamaterial matching layer (UMML) that possesses specific permittivity and permeability tensors. We demonstrate this concept by synthesizing a physical UMML to match a high-index (εr= 10.2) substrate at 45°. The required permittivity and permittivity tensors of the UMML are achieved through the judicious control of the tangential and longitudinal electric and magnetic responses. Around -30 dB reflections are observed for both polarizations at the design angle. Building on the UMML concept, we design a novel radome in microwave regime with a near omni-directional matching performance. For incident angles from 0°-85°, reflections remain below -14 dB for both polarizations. To our best knowledge, this is the widest angular range that has been achieved while maintaining less than 5% power reflection for both polarizations. The proposed UMML concept offers a new paradigm for designing high-performance microwave, terahertz, and optical devices.