Improving the Azimuthal Resolution of HFSWR With Multiplicative Beamforming

The use of multiplicative beamforming is described to improve the azimuthal resolution of existing high-frequency surface-wave radar (HFSWR). An existing method by Davies and Ward is used to improve the resolution by a factor of more than two for HFSWR with 16 antennas. The long integration time of HFSWR suppresses the cross products which are the usual drawbacks of this process. The concept is then validated on experimental data with synthetic targets.

I. Introduction

Owing to its particular kind of propagation, high-frequency surface-wave radar (HFSWR) can provide information about both the objects that can be found on the sea surface and the characteristics of the sea itself. The first case usually deals with military applications of HFSWR, while the second case addresses civilian applications, usually in oceanography [1]. Whatever the application, standard issues include range and azimuthal resolutions. The range resolution issue is solved by the use of special waveforms [2]. As for azimuthal resolution, this usually means using more elements to obtain a large array, therefore increasing complexity. Another solution is the use of a multiple-input multiple-output system [3]. This letter presents a simpler yet efficient solution using an existing phased-array radar with few modifications. It is based on the use of a multiplicative receiving array [4]–[6]. Section II will present the theory and its use for HFSWR. Then, an experimental validation with synthetic targets will be described in Section III.