The impact of local resonance on the enhanced transmission and dispersion of surface resonances

TL;DR

This study explores how local resonances influence microwave transmission through metallic aperture arrays, revealing that even-mode resonances are affected by local geometry, while odd-mode resonances depend on periodicity, affecting surface wave behavior.

Contribution

It provides a detailed analysis of surface resonances in metallic aperture arrays, distinguishing the roles of local resonances and periodicity in transmission enhancement.

Findings

Enhanced microwave transmission linked to surface resonances.

Even-mode resonances depend on local aperture geometry.

Transmission extrema align with dispersion diagram degeneracies.

Abstract

We investigate the enhanced microwave transmission through the array of metallic coaxial annular apertures (MCAAs) experimentally and theoretically. The even-mode and the odd-mode surface resonances are clarified from the spatial field distributions and the dispersion diagram. The impact of local resonance is thoroughly embodied in the even-mode surface resonant states, while the odd-mode surface resonances are scaled by periodicity, invariant to different local geometry of the unit cell, and invisible in measurements. The enhanced transmission is the collective selections on the interplay between the local resonances and the evanescent Bloch wave channels on the surface. Transmission measurements for different inner diameter of the apertures show that the transmissivity extrema with respect to the specific angles precisely correspond to the degenerate points in the dispersion diagram of surface resonances.