Sparsity of radiating characteristic modes on infinite periodic structures

TL;DR

This paper investigates the radiating characteristic modes of infinite periodic structures using spectral dyadic Green's functions, revealing that the number of radiating modes is limited and that these modes form a sparse basis for reflection analysis.

Contribution

It introduces a spectral Green's function approach to characterize radiating modes on infinite periodic structures and shows their limited number and sparse nature in reflection studies.

Findings

Number of radiating modes is limited by unit cell size and incident wavevector.

Characteristic modes form a sparse basis for reflection phenomena.

Modal contributions can be decomposed from the reflection tensor.

Abstract

Characteristic modes on infinite periodic structures are studied using spectral dyadic Green's functions. This formulation demonstrates that, in contrast to the modal analysis of finite structures, the number of radiating characteristic modes is limited by unit cell size and incident wavevector (i.e., scan angle or phase shift per unit cell). The reflection tensor is decomposed into modal contributions from radiating modes, indicating that characteristic modes are a predictably sparse basis in which to study reflection phenomena.