Phaseless Measurements Over Nonrectangular Planar Near-Field Systems Without Probe Corotation

The need for acquiring the near-field phase with a high precision has imposed a stringent condition for measuring the antennas pattern at high frequencies in indoor facilities. The phaseless near-field techniques are introduced to overcome the necessity of operating with costly high frequency vector instruments. Many algorithms are proposed by the researchers and among them the Iterative Fourier technique is proved a viable solution for planar near-field systems. This paper discusses a difficulty in implementing this technique in nonrectangular facilities, such as plane-polar and bipolar, and introduces an iterative algorithm to alleviate it. The measurement of the co and cross-polarized field necessitates the corotation of the probe with the antenna under test to maintain the polarization, for all the nonrectangular planar systems. The corotation increases the hardware complexity of these measurement systems. Therefore the proposed algorithm which alleviates the probe corotation can significantly simplify the hardware involved. The convergence and stability of the proposed algorithm is studied and it is shown how one can control them. The developed algorithm is implemented using simulated near-field for two different types of antennas. The applicability of this algorithm is also assessed by employing a bipolar phaseless near-field measurement.