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.ngetikin.com/hot-mega-Ventilationstejp-50-mm-Fresh-flash-find/