Phase‐reconstruction from magnitude‐only data of electrically small antennas for body‐centric wireless communication

A method for phase retrieval from magnitude‐only data for electrically small antennas intended for use in relation to body‐centric wireless communication, is presented. The method utilizes the spherical wave expansion (SWE) description of the electromagnetic field radiated by the antenna under test (AUT). The expansion coefficients of the SWE are optimized such that errors between the reconstructed and provided data magnitudes are as small as possible. The required additional phase information is acquired from additional magnitude‐only data sets of the AUT in different orientations. These orientations are defined by rotations of the AUT along the Eulerian angles. The performance of the method is evaluated for a realistic configuration, which consists of an inverted‐A antenna in the vicinity of an ear. The sensitivity of the method to the angular resolution of the field data, as well as to the Eulerian rotation accuracy, is investigated. Finally, the reconstruction method is tested on a set of practical antenna measurements conducted in an RF‐anechoic chamber.