System parameter design of multimodal small satellite SARs operating in scan mode and transmit power optimization for marine scenes

Multimodal small satellite synthetic aperture radar (SAR) is a new radar system under development that integrates an SAR, altimeter, scatterometer, and spectrometer. When applied to marine scenes, this system can be used to measure both marine targets and marine dynamic environments with high precision. This study addresses system parameter design for multimodal small satellite SAR operating in scan mode, and this design provides system parameters such as antenna size, signal bandwidth, pulse repetition frequency, scanning wavenumber and wave position for system simulation in scan mode. A method for optimizing the transmit power when illuminating a marine scene based on the wind speed and wind direction above the sea surface is studied. The goal is to fully use the characteristics of strong sea surface microwave scattering under a suitable wind speed and wind direction to reduce the required transmit power, thus improving the available data sampling time per orbit of a multimodal radar when working in SAR mode. Various simulation experiments were conducted, and the system parameter design results are given under scan mode. Furthermore, imaging simulation results of ocean scenes are also given under conventional and decreased power after optimization. The results show that good ocean scene imaging results are obtained when the designed system parameters are used for system simulation. In addition, the simulation results also verify that when the sea surface wind speed is relatively high and the wind direction is suitable, an acceptable ocean scene imaging result can still be obtained by using reduced transmit power.