Redefining uniform circular array’s limit by using square patch elements for higher order orbital angular momentum mode generation

Abstract

This article proposes a technique to design the Uniform Circular Array (UCA) antenna for the generation of higher order of orbital angular momentum (OAM) modes using lesser number of antenna elements. Earlier, the highest possible OAM mode number (lmax) generated using conventional N-element UCA is limited by number of antenna elements N ≥ 2|lmax|. In the proposed design, a square patch element is placed between two antenna elements of conventional 4-element UCA to generate higher order OAM modes (0, ±1, ±2, and ±3 OAM modes) with lesser number of antenna elements. The proposed UCA is compact in size and requires less complex power dividing phase networks in comparison to conventional 8-element UCA to generate similar lmax. The proposed UCA with square patch is designed at 5.2 GHz and lmax of a N-element UCA with square patch is now limited by number of antenna elements as N ≥ |lmax|. The simulated and measured phase patterns for various OAM modes are in good agreement and supported by mathematical analysis. A comparison of the new structure with the conventional Uniform Circular Arrays available in the literature is also tabulated.