The beam-scan allows the terrain observation by progressive scans (TOPS) mode to cover large azimuthal scenes in a short time. which also causes aliasing in both Doppler domain and azimuth time domain. In the TOPS mode. the most popular solution to overcome the aliasing problem is the “sub-aperture” method. https://www.ealisboa.com/mega-sale-Sol-Sunguard-Altitude-Sunscreen-1-5oz-big-savings/