Antenna Modelling by Infinitesimal Dipoles based on near Field Measurements

In this paper, we present a method to determine the constellation of elementary dipoles that can simulate the antenna under test (AUT) behaviour from spherical near field measurements. It is based on the substitution of the actual radiating device by an equivalent set of infinitesimal dipoles (electric and magnetic), distributed regularly over a fictitious sphere surrounding the AUT. This equivalent set of elementary dipoles is optimized using the spherical wave expansion (SWE) of the measured near field and by using mode matching method. Since the current excitation of each elementary dipole is known, the radiated field by the AUT model at different distance can be calculated. The method is tested using synthesized data issued from the simulation of canonical patch antenna.