Arbitrary Wave Transformations with Huygens' Metasurfaces through Surface-Wave Optimization

TL;DR

This paper introduces a novel method for designing Huygens' metasurfaces that employs auxiliary surface waves to control electromagnetic wave transformations, overcoming traditional power conservation limitations.

Contribution

It presents a surface-wave optimization technique enabling arbitrary wave transformations with high efficiency and minimal reflections, expanding the capabilities of passive metasurfaces.

Findings

Achieved 92% aperture illumination efficiency.

Demonstrated control of wavefronts with different incident and output power profiles.

Analyzed effects of evanescent spectrum on losses and bandwidth.

Abstract

Huygens' metasurfaces have demonstrated the ability to tailor electromagnetic wavefronts with passive low-profile structures. The fundamental constraint enabling passive and ideally lossless solutions is the conservation of the normal real power locally along the metasurface. In this work, we examine the use of auxiliary surface waves to overcome this limitation and design Huygens' metasurfaces for wave transformations with different incident and output power density profiles. The developed method relies on the optimization of a surface-wave distribution that is utilized to redistribute the power at the input side of the metasurface without incurring any reflections. A full design example is presented with a linear patch array along the H-plane illuminating a metasurface that produces uniform output fields along the E-plane. A high aperture illumination efficiency of 92% is obtained despite the small distance between the source and the metasurface. Moreover, the effects of the evanescent spectrum to the losses and the bandwidth of the structure are discussed.