Deep Subwavelength Electromagnetic Transparency through Dual Metallic Gratings with Ultranarrow Slits

TL;DR

This paper investigates microwave transmission through dual metallic gratings with ultranarrow slits, revealing a novel deep subwavelength resonance explained by new physical models, with potential applications in compact electromagnetic devices.

Contribution

The study introduces a new understanding of deep subwavelength electromagnetic transparency using dual metallic gratings, supported by both microscopic and macroscopic models.

Findings

Observed a transmission peak at a wavelength much larger than the structure's characteristic length.

Developed LC-circuit-based and effective-medium models to explain the resonance.

Demonstrated potential for compact, imperfection-immune electromagnetic applications.

Abstract

In this Letter, we study the transmission response of microwaves through two identical metallic plates machined with ultranarrow slit arrays. The measured and calculated transmission spectra consistently display a striking transmission peak at wavelength much larger than any characteristic length of the structure (e.g., about twenty-fold of the lattice period), which can not be directly explained by the existing mechanisms. Both the LC-circuit-based microscopic picture and the effective-medium-based macroscopic model are established to capture the essential physics behind such unexpected resonance at the deep subwavelength scale. Prospective applications of this novel transmission property can be anticipated, considering the merits of compact and excellent immunity to structural imperfections.