INVERSE SOURCE NF-FF TRANSFORMATION APPLIED TO UAV-BASED NEAR-FIELD ANTENNA MEASUREMENTS

An inverse source Near-Field Far-Field (NF-FF) transformation is applied to NF samples on measured flight paths performed by a UAV at 175 MHz. A radio- telescope prototype constituted of 16 active elements equipped with digital beamforming is characterized through two large horizontal quasi-planar rasters at constant altitude performed by the UAV. The two tangential electric field components needed for the NF-FF transformation are acquired (i.e., one component for each flight). Differently from standard NF-FF transformations, these two components are sampled on two different sets of points. This aspect is verified applying the inverse source method on a set of simulated NF data. NF-FF transformed results are compared and validated with direct FF simulations.