An optimal determination of variable antenna height and power for in-orbit SAR operations

An optimal power and antenna height determination over a wide range of incidence angles is proposed for in-orbit operations of the spaceborne stripmap synthetic aperture radar (SAR) with variable antenna height and variable radiating element power. The antenna height and the average transmitted radio-frequency power of a radiating element for each incidence angle are determined so that the mapping area can be maximized with the constraints on the signal-to-noise ratio, ambiguities, and swath width, given the SAR geometry (an altitude and incidence angles) and radar wavelength. With the receive-chain power consumption of one transmit/receive module (P_r=10 mW) and the SAR instrument power consumption without the phased array antenna (P_I=5 W), the illustrative design example shows that the mapping area of the proposed SAR for the maximum incidence angle (η^max=75°) is about 269.1% of that resulted from utilizing only the variable antenna height. The proposed optimization would have a more beneficial effect on applications that need the high-incidence-angle operations.