Performance Evaluation of Phase-angle Gradient Method for Phase Retrieval Based on Low-frequency Amplitude-only Near-field Data

The Phase Angle Gradient Method (PAGM) is a recent technique developed for phase retrieval based on amplitude-only measurement data. Preliminary results have shown that the PAGM is able to perform phase retrieval at 100 MHz with accurate phase information based on measured field components on three planar surfaces. In this paper, a performance evaluation of the PAGM under different configurations is conducted. Phase retrieval based on field measurements for different plane sizes and separations between the planes are studied rigorously. In addition, the PAGM is tested for different initial phase distributions. The results show that the PAGM is capable of retrieving phase information even if the separation between the measurement planes is small in terms of wavelengths.