Iteration-free phase retrieval for amplitude-only near to far field transformation

Near to far field transformation is widely used to predict antenna radiation pattern when it is difficult to conduct far-field measurement. Due to the difficulty of phase measurement, near to far field transformation using amplitude-only data attracted much interest. In order to transforming amplitude-only near field to far field, phase retrieval is often needed. Most existing phase retrieval methods iteratively retrieve phase information from field amplitudes on well-separated observation planes, which requires physically large test site for low frequency applications.