Directive Emission Obtained by Coordinate Transformation

TL;DR

This paper introduces a coordinate transformation method to design substrates that can control and concentrate the emission of embedded sources into narrow beams, overcoming traditional limitations related to slab thickness and source placement.

Contribution

It presents a novel application of coordinate transformation theory to achieve directive emission in space-variant media with physically realizable reduced parameters.

Findings

Radiated energy can be concentrated into a narrow beam using the proposed transformations.

The slab thickness is no longer limited by evanescent modes.

The method allows flexible source placement without altering the radiation pattern.

Abstract

We use coordinate transformation theory to realize substrates that can modify the emission of an embedded source. Simulation results show that with proper transformation functions the energy radiated by a source embedded in these space variant media will be concentrated in a narrow beam. The thickness of the slab achieved with our transformations will no longer be restricted by the evanescent modes and the source can be placed at any position along the boundary of the substrate without affecting the radiation pattern. We also discuss the case where reduced parameters are used, which still performs well and is physically realizable.