Progress in the understanding of narrow directional microwave scattering of agricultural fields

Directional microwave scattering, as investigated in this study, is characterized by a strong and narrow scattering pattern that varies strongly for only minor aspect angle changes. As was noted already in the past directional scattering is relevant for applications and cannot just be ignored. The overall objective of our work was to better understand directional scattering. Suited space- and airborne SAR data over several agricultural sites together with related in-situ information were collected for this purpose. Directional scattering was identified by comparison of backscattering acquired with only slightly different aspect angles as available from ERS–ENVISAT pairs with significantly different Doppler Centroids or by comparing azimuth spectrum sub-bands with slightly different Doppler Centroid. Major progress achieved in this work includes the much improved experimental evidence available and significant improvements in the understanding of the scatter phenomenon through the developed scatter model. Good progress was also made in the detection of directional scattering.

Research highlights
► Experimental evidence for directional scattering.
► Strong directionality for potato, carrot, onion, sugar beet and wheat fields.
► Significant progress concerning the understanding of the directional scattering.
► Model presented predicting narrow directional scattering patterns.