Application of the Reduced-Order Model to Planar Near-Field Antenna Measurements

The antenna characterization from planar Near-Field (NF) measurements is commonly realized by using the classical Near-Field to Far-Field Transform (NFFFT) technique of Plane Wave Expansion (PWE). Truncation effects are induced by this approach due to the finite size of the measurement scan surface, which is an issue for wide angular range beam steering applications. To overcome these limitations, an equivalent model of the Antenna Under Test (AUT) based on a distribution of infinitesimal dipoles and coupled with a Reduced-Order Model (ROM) of the problem, is proposed. The powerful ability of the ROM in determining the number of samples needed for accurate NF measurements is detailed. Moreover, the use of non-conventional measurement geometry to limit the truncation effects for strong beam tilts is studied. The analysis of our approach on simulated NF data shows that, compared to the PWE technique, only 20% of samples are needed to achieve an accurate characterization.