A New Approach to Phase Retrieval and its Application to Reflector Antennas Diagnostics

We present a new approach to the general phase retrieval problem. By profitably using the 'Spectral Factorization' technique in conjunction with multipole expansions derived from the 'Orbital Angular Momentum' aperture antenna theory, the approach allows to effectively solve the problem by exploiting only one measurement surface. By so doing, and without requiring the exploitation of computationally-expensive global-optimization algorithms, the approach allows the reflector antenna surface diagnosis starting from far-field phaseless data.