# 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.

## Key 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.

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Source: https://tomesphere.com/paper/1702.05667