Abstract
The space-borne P-band synthetic aperture radar (SAR) maintains excellent penetration capability. However, the low carrier frequency restricts its imaging resolution. The sliding spotlight mode provides an operational solution to meet the requirement of high imaging resolution in P-band SAR design. Unfortunately, the space-borne P-band SAR will be inevitably deteriorated by the ionospheric scintillation. Compared with the stripmap mode, the sliding spotlight SAR will suffer more degradation when operating in the scintillation active regions due to its long integration time and complex imaging geometry. In this paper, both the imaging performance and scintillation effect for P-band sliding spotlight mode are studied. The theoretical analysis of scintillation effect is performed based on a refined model of the two-frequency and two-position coherence function (TFTPCF). A novel scintillation simulator based on the reverse back-projection (ReBP) algorithm is proposed to generate the SAR raw data for sliding spotlight mode. The proposed scintillation simulator can also be applied to predict the scintillation effect for other multi-mode SAR systems such as terrain observation by progressive scans (TOPS) and ScanSAR. Finally, a group of simulations are carried out to validate the theoretical analysis.
Highlights
It is widely known that synthetic aperture radar (SAR) system working at P-band shows its superiority in penetrating the forest foliage and the ground surface, which will have an extensive application prospect in biomass measurement and geological observation [1,2,3]
We firstly introduce the observation geometry of sliding spotlight SAR system in
The simulations are performed by using the reverse back-projection (ReBP)–based SAR–SS which is shown in Figure 9 and the detailed process is described as follow: The single look complex (SLC) image is used as the input and the image scene is defined in the earth-centered earth-fixed (ECEF) coordinate
Summary
It is widely known that synthetic aperture radar (SAR) system working at P-band shows its superiority in penetrating the forest foliage and the ground surface, which will have an extensive application prospect in biomass measurement and geological observation [1,2,3]. Little literature has been proposed to evaluate the ionospheric effect for P-band sliding spotlight SAR system. In Carrano’s work, the inverse range-Doppler algorithm (RDA) is applied to generate the unaffected SAR signal It cannot simulate the observation geometry of SAR system, it is not suitable to reconstruct the SAR raw data for the sliding spotlight SAR system. Compared with the stripmap mode, the P-band sliding spotlight SAR system has an ultra-long integration time and more complicated observation geometry which means a longer exposure time and a longer ionospheric penetration length (IPL). Due to the beam scanning, the incident angle of beam center, which is an important parameter in scintillation simulations, varies within the acquisition time All these characteristics will make the scintillation effect on sliding spotlight mode show different patterns. Monte-Carlo simulations are carried out to validate the theoretical analysis
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