A Closed-Form Solution for the Synthesis of the Excitations of a Plane Wave Generator

Plane Wave Generators (PWG) represent an attractive technology for the measurement of 5G New Radio base station antennas since they significantly reduce the dimensions of the required anechoic chamber. By properly selecting the complex weights of the array, a PWG allows to generate a planar wavefront in a confined volume within the array near-field region, known as Quiet Zone (QZ). In this paper, the "minimum error field norm" method is exploited to synthesize the PWG excitations. In addition to having a closed-form solution, this technique allows to control the tradeoff between the PWG performance and the amount of power that flows through the QZ. The method is applied to an octagonal-shaped planar array with 156 elements to create a spherical QZ, and its performance is evaluated for various values of the QZ radius. Finally, the method is compared with the simpler Conjugate Phase method with Dolph-Chebyshev amplitude tapering.