Yuepeng Wu

Target angle estimation with a single-channel wide beam antenna is a fundamental and crucial task in radar and remote sensing. Traditional target-angle estimation methods primarily rely on the phase differences of electromagnetic waves between array antennas, resulting in a high level of complexity in the antenna system. Furthermore, the angle estimation accuracy is also limited by the array antenna aperture. To alleviate the problems of system complexity and aperture limitations, a multi-media nonlinear wavefront modulation system (MN-WMS) for angle estimation is proposed. This system does not require modification of the original wide-beam antenna; therefore, the system complexity is low. By introducing nonlinear wavefront modulation information, the target angle can be accurately estimated. Specifically, we first propose a wavefront modulation angle estimation principle that introduces additional reference information for the angle estimation task. Then, we propose a multi-media modulator for electromagnetic waves modulation and present the implementation of the modulator. Finally, a multi-media nonlinear wavefront modulation angle estimation algorithm (MN-WMA) is proposed, which can be adaptively adjusted to balance processing time and accuracy require ments. High-accuracy angle estimation for a single-channel wide beam antenna can be effectively realized. Microwave anechoic chamber experiments show that the method achieves an angle-measurement accuracy of 0.163◦ with the single-channel wide beam antenna, verifying the effectiveness of the proposed method. This is a new exploration of using the nonlinear wavefront modulation method for angle estimation with a single-channel wide-beam antenna.

Overcoming the angular resolution limitations imposed by antenna apertures remains a critical challenge in radar systems. The nonlinear wavefront modulation technique enables angular resolution beyond the limitations of antenna beamwidths while maintaining the physical aperture size. This article proposes a novel method to enhance angular resolution within a single beamwidth by employing nonlinear wavefront modulation and investigates both the theoretical and experimental aspects of this technology. First, a wavefront modulation signal model is established, and the resolution enhancement factor (REF) is defined to quantify the performance of angular resolution enhancement. Two analytical criteria—the subspace distance criterion and Cramér–Rao bound (CRB) criterion—are proposed to evaluate resolution performance. An $L$ -band verification system is constructed, and experiments are conducted in a microwave anechoic chamber. Results validate the angular resolution enhancement principle and confirm the system’s ability to resolve multiple targets within the single beamwidth in both azimuth and elevation. In the experiment, our method successfully discriminates multiple targets with a minimum azimuth separation of 1.08° and a minimum elevation separation of 5.14°, despite the broad beamwidths of the receiving antenna (67° in azimuth and 98° in elevation). Finally, a comprehensive analysis assesses the system under varying signal-to-noise ratios (SNRs), numbers of wavefront modulation states, and calibration errors. This study provides a rigorous foundation for the principles and engineering implementation of nonlinear wavefront modulation, offering significant utility for future radar system design.