An improved synthetic aperture radar cross-range resolution method based on Matched Slope Filter

This article aims at the improvement of Synthetic Aperture Radar (SAR) resolution by using a Matched Filter (MF) based on the Fractional Fourier Transform (FrFT) that has been called a Matched Slope Filter (MSF). Generally, the received SAR signals are processed by well-known algorithms to extract the final image, such as the Chirp Scaling Algorithm (CSA) and the Range Doppler Algorithm (RDA). Implementing a Matched Filter (MF) that aims at compressing the received signal in the range and azimuth directions is a principal part of these algorithms to deliver target positioning and high resolution. Because the transmitted signal by SARs has often been Linear Frequency Modulated (LFM), the received echo from the targets in the range direction is the LFM. On the other hand, there is always a chirp signal in the azimuth orientation. Thus, this paper proposes the Matched on Slope Filter to improve the compression of the azimuth signals. It's clear the proposed method has been adopted for LFM signal compression in the range direction also. The evaluation results show that our method that uses the FrFT in the time-frequency domain for implementing a Matched Slope Filter enhances the resultant azimuth resolution and reduces the sidelobe level compared to the other frequency-based method.