Orbital Angular Momentum Antennas: Understanding Actual Possibilities Through the Aperture Antennas Theory

TL;DR

This paper uses Aperture Antennas Theory to analyze the limitations of Orbital Angular Momentum antennas in far-field communication, providing insights into their degrees of freedom and confirming recent findings.

Contribution

It introduces a simple method based on Aperture Antennas Theory to understand OAM antenna limitations and analyzes the properties of source and far-field operators for different vortex orders.

Findings

Results agree with recent studies by Edfors and Craeye

Identifies additional drawbacks of OAM antennas

Discusses the degrees of freedom for different vortex orders

Abstract

We propose a simple method based on the Aperture Antennas Theory to understand in a simple fashion limitations of OAM antennas in far-field links. Additional insight is also given by analyzing the properties of the operators relating source and far-field distributions for a given order of the vortex. The outcomes fully agree with the results recently achieved by Edfors, Craeye, and co-authors, and emphasize some additional draw-back. The "degrees of freedom" of the fields associated to the different orders of the vortices are also discussed.