On the Potential of Multi-Mode Antennas for Direction-of-Arrival Estimation

TL;DR

This paper demonstrates that multi-mode antennas can effectively replace phased arrays for direction-of-arrival estimation, using calibration and modeling techniques to achieve accurate results in 2D and 3D scenarios.

Contribution

It introduces methods for DoA estimation with single multi-mode antennas, including calibration-based modeling and performance assessment in simulations.

Findings

Wavefield modeling outperforms array interpolation technique at high SNR.

Coherent DoA estimation is more accurate than non-coherent, especially in 3D.

Single MMA can achieve accurate DoA estimation in both 2D and 3D cases.

Abstract

In this paper, we show that a multi-mode antenna (MMA) is an interesting alternative to a conventional phased antenna array for direction-of-arrival (DoA) estimation. By MMA we mean a single physical radiator with multiple ports, which excite different characteristic modes. In contrast to phased arrays, a closed-form mathematical model of the antenna response, like a steering vector, is not straightforward to define for MMAs. Instead one has to rely on calibration measurement or electromagnetic field (EMF) simulation data, which is discrete. To perform DoA estimation, array interpolation technique (AIT) and wavefield modeling (WM) are suggested as methods with inherent interpolation capabilities, fully taking antenna nonidealities like mutual coupling into account. We present a non-coherent DoA estimator for low-cost receivers and show how coherent DoA estimation and joint DoA and polarization estimation can be performed with MMAs. Utilizing these methods, we assess the DoA estimation performance of an MMA prototype in simulations for both 2D and 3D cases. The results show that WM outperforms AIT for high SNR. Coherent estimation is superior to non-coherent, especially in 3D, because non-coherent suffers from estimation ambiguities. In conclusion, DoA estimation with a single MMA is feasible and accurate.