An Azimuth Antenna Pattern Estimation Method Based on Doppler Spectrum in SAR Ocean Images.

Area of Science:

• Remote Sensing
• Oceanography
• Signal Processing

Background:

• Estimating accurate azimuth antenna patterns (AAP) in synthetic aperture radar (SAR) ocean images is challenging due to low scattering.
• The absence of strong scattering targets further complicates traditional AAP estimation methods.

Purpose of the Study:

• To propose a novel method for estimating the azimuth antenna pattern (AAP) in SAR ocean images using Doppler spectrum analysis.
• To address the difficulties in AAP estimation caused by low-scattering environments in ocean remote sensing.

Main Methods:

• Re-imaging SAR raw data using an azimuth unweighted matched filter to preserve complete AAP information.
• Obtaining the AAP shape factor through linear statistics of the Doppler center and edge frequency spectrum relationship.
• Analyzing the impact of image uniformity and signal-to-noise ratio on estimation accuracy via simulation.

Main Results:

• The proposed method successfully estimates the azimuth antenna pattern (AAP) in SAR ocean images.
• Feasibility validated using ERS-2 satellite data, demonstrating good estimation results.
• Simulations confirmed the influence of image uniformity and SNR on the estimation outcomes.

Conclusions:

• The Doppler spectrum-based method provides an effective solution for AAP estimation in SAR ocean remote sensing.
• The technique is robust and applicable even in challenging low-scattering conditions.
• The study validates the practical utility of the proposed method with real-world satellite data.