Self-calibration and antenna grouping for bistatic oceanographic High-Frequency Radars

TL;DR

This paper introduces self-calibration and antenna grouping techniques for bistatic oceanographic HF Radars, enhancing surface current mapping accuracy and robustness through real-time array gain correction and multi-scale direction finding.

Contribution

It presents novel methods for real-time array self-calibration and multi-scale direction finding using antenna grouping, improving radar surface current mapping.

Findings

Enhanced surface current maps with full coverage

Robustness to missing antennas in the array

Real-time calibration without operator intervention

Abstract

We propose two concepts for the significant improvement of surface current mapping with bistatic oceanographic High-Frequency Radars. These ameliorations pertain to the azimuthal processing of radar data with linear or quasi-linear antenna arrays. The first idea is to take advantage of the remote transmitter to perform an automatic correction of the complex gains of the receiving antennas based on the analysis of the signal received in the direct path. This direct signal can be found at the zero-Doppler and minimal range cell in the Range-Doppler representation. We term this adjustment as "self-calibration" of the receiving array, as it can be performed in real-time without any specific action from the operator. The second idea consists in applying a Direction Finding technique (instead of traditional Beam Forming) not only to the full array of antenna but also to subarrays made of a smaller number of sequential antennas, a method which we refer to as "antenna grouping". The combination of self-calibration and antenna grouping makes it possible to obtain high-resolution maps with full coverage, thereby combining the respective merits of Direction Finding and Beam Forming techniques. In addition the method is found robust to missing antennas in the array. These techniques are applied to and illustrated with the multistatic High-Frequency Radar network in Toulon.