Work

Robust Beamforming for Superdirective Antenna Arrays and Experimental Validations

Year: 2025

Type: article

Abstract: Superdirective antenna arrays have the potential to increase array directivity proportional to the square of the number of antenna elements. However, the high sensitivity problem of superdirectivity has posed a major challenge for practical applications. To address this issue, we propose a robust superdirective beamforming method that accounts for mutual coupling between antenna elements. We first introduce a universal sensitivity measurement applicable to coupled arrays and derive its closed-form expression, termed the degree of sensitivity (DoS). A beamforming optimization problem is then formulated to maximize the directivity factor while satisfying a DoS constraint, resulting in a parameterized beamformer where the parameter is difficult to determine. To solve this optimization problem, we propose an efficient orthogonal complement-aided quadratic constraint least squares (OC-QCLS) algorithm, which achieves the maximum possible directivity under the sensitivity constraint. Specifically, the framework of the least squares problem with a quadratic constraint is utilized to provide useful insights, and the intractable secular equation for the parameter is transformed into an easy-to-solve polynomial equation using the orthogonal complement. Numerical and electromagnetic (EM) simulations verify the effectiveness of the DoS and the OC-QCLS algorithm. The improvement in communication performance achieved by the OC-QCLS algorithm is demonstrated through its superior average spectral efficiency. Furthermore, an eight-dipole superdirective antenna array prototype with 0.20λ element spacing operating at 1.6 GHz is built, and real-world experiments validate the proposed method. Notably, the distributions of directivity metrics are analyzed and demonstrated in both simulation and experimental results.

Source: IEEE Open Journal of the Communications Society

DOI: 10.1109/ojcoms.2025.3589033

Authors: Mengying Gao, Haifan Yin, Liangcheng Han, Jingcheng Xie

Institution: Huazhong University of Science and Technology

Language: English

Topic: Antenna Design and Optimization

Subfield: Aerospace Engineering

Field: Engineering

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $2,075

Funders: National Natural Science Foundation of China, Fundamental Research Funds for the Central Universities