Equivalent source modelling and reconstruction for antenna measurement and synthesis

In this paper we present an algorithm that from a given 2D radiation pattern (in near, Fresnel or far field region) identifies a linear distribution of equivalent magnetic current. The equivalent current distribution radiates in an unbounded medium a field that best fits (in the sense of rms error) the given radiated field. The purpose of this paper is to discuss different alternatives of modeling the equivalent currents in terms of choosing the appropriate basis functions for each application. The first application is the obtention far field patterns of antennas, with separable distribution, from measurements in the near or Fresnel field regions. If we associate the given 2D radiation pattern to the field data measured in an anechoic chamber facility and we associate the equivalent currents to the tangential fields in the plane of the antenna under test (AUT) then we can obtain the field at any distance and thus the far field radiation pattern. The second application is the synthesis of linear arrays by associating the given 2D radiation pattern to the desired far field pattern and admitting a tolerance error in terms of the typical deviation at each aspect angle. The reconstructed equivalent current distribution can be used to synthesize an antenna by means of an array of slots or conducting patches (sampling of the reconstructed current distribution).