DOA Estimation of an Enhanced Generalized Nested Array with Increased Degrees of Freedom and Reduced Mutual Coupling

Yule Zhang,Chenghong Zhan,Fangzheng Zhao,Hao Zhou,Junpeng Shi,Guoping Hu,Liangtian Wan

doi:10.1155/2021/7233651

Abstract

Aiming at low degrees of freedom (DOF) and high mutual coupling (MC) of the existing sparse arrays, an enhanced generalized nested array (EGNA) is proposed in this paper. Specifically, the proposed array adds a single antenna on the basis of generalized nested array (GNA), and the difference of coprime factors is employed as the spacing between the second subarray and the additional antenna. Then, the values of the coprime factors are analyzed in detail, which indicates that Yang-NA can be explained as a special case. Compared with the majority of the existing sparse arrays, EGNA not only has the closed-form expressions of the physical antenna locations, consecutive lags, and unique lags, but also significantly increases DOF and reduces MC. In view of the above advantages, EGNA can obtain superior performance in direction of arrival (DOA) estimation. Numerical simulation results verify the rationality and superiority of the proposed nested array.

Highlights

A basic technology of array signal processing is the direction of arrival (DOA) estimation, which is one of the essential research tasks in the fields of communications, radar, sonar, and electronic countermeasures in the past decades and future [1,2,3,4]. e conventional DOA estimation generally considers uniform linear array (ULA) in theoretical research and engineering applications, whereas the antenna spacing is no more than half wavelength
With the intention of ulteriorly increasing degrees of freedom (DOF) and reducing mutual coupling (MC) at the same time, we propose an enhanced generalized nested array (EGNA) in this paper
Yang-NA [20] can be considered as a special case of EGNA

Summary

Introduction

A basic technology of array signal processing is the direction of arrival (DOA) estimation, which is one of the essential research tasks in the fields of communications, radar, sonar, and electronic countermeasures in the past decades and future [1,2,3,4]. e conventional DOA estimation generally considers uniform linear array (ULA) in theoretical research and engineering applications, whereas the antenna spacing is no more than half wavelength. E conventional DOA estimation generally considers uniform linear array (ULA) in theoretical research and engineering applications, whereas the antenna spacing is no more than half wavelength. Shi et al [24] flexibly adjusted the interelement spacing of NA and obtained a generalized nested array (GNA) with lower MC, but it does not enhance DOF. These modifications only consider one of the DOF and MC, which limits DOA estimation performance. EGNA exploits two coprime factors to increase the interelement spacing of two-level nested array and takes the difference of these two coprime integers as the spacing between the second subarray and the additional antenna.

Preliminaries

Signal Model with Mutual Coupling

Enhanced Generalized Nested Array

D2 α–1 α

Simulation Experiments

Conclusion