Due to complex geometry (urban canyons generate multiple scattering) SAR images are difficult to interpretate on urban areas. In order to characterize Non Line Of Sight (NLOS) scattering phenomenon at Ka band, measurement campaigns have been performed using the ONERA BUSARD motor glider and a dedicated Ka band SAR sensor. From 2011 to 2014 a large number of measurements flights have been done, leading to the acquisition of a radar dataset that covers different geometries and different acquisition modes: Single channel, cross-track or along-track interferometry modes. NLOS radar echoes have been investigated on two types of materials: concrete and metallic walls and different geometries of acquisition. NLOS echoes observation has been validated in various cases and interferometry modes have been proved to be efficient in NLOS echoes detection and validation.