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Spaceborne synthetic aperture radar (SAR) systems operating at low frequency, such as L- and P-bands, are significantly influenced by ionospheric effects. One of the remarkable effects is Faraday rotation (FR), which is known as a serious error source for the polarimetric SAR (PolSAR) application. The FR effect mainly results from the background ionosphere so that the FR angles (FRAs) within a SAR image tend to take on a potential spatial-variable distribution. The typical estimator is used to accurately estimate FRA from the PolSAR data. Moreover, a step-to-step procedure is proposed to derive FRA map. On the basis of the real data processing, the experimental results validate the effectiveness of the FRA map, which indicates the immense capability of the PolSAR data to retrieve a spatial distribution of the FRA. [ABSTRACT FROM AUTHOR]

There are a large number of high-energy particles in the space. These high-energy particles induce a single-event upset effect on DSP, FPGA, and other programmable digital controllers inside the beam-steering unit, which can produce unpredictable and erroneous influences, thereby reducing the reliability of space-borne-phased array radars. In order to solve the above problems, this study presents a design of beam-steering unit based on a kind of application-specific integrated circuit (ASIC). By using the advantages of ASIC circuits such as strong radiation resistance, high integration, and low power consumption, this solution adopts an anti-irradiation ASIC chip as a controller, and anti-irradiation RS422 transceivers are used to complete interface conversion for receiving data and transmitting data. The beam refreshing and telemetry functions between the beam control computer and the 24 microwave modules are realised finally. The test result shows that the phase distribution time is <30 μs when the clock is 3.125 MHz, and the falling edge of sampling pulse is located at half the length of a data symbol, ensuring data hold time long enough to sample correctly. [ABSTRACT FROM AUTHOR]