A two probes scanning phaseless near-field far-field transformation technique

An innovative and effective technique to determine the far field of a radia ting system from near-field intensity data is introduced, analyzed, and tes ted. The approach is based on the simultaneous measurement of the amplitude of the voltages received by two different probe antennas moving over a sin gle scanning surface in near zone and performs the phase retrieval of the n ear field by assuming as unknown the plane wave spectrum of the field. The radiated held is then straightforwardly evaluated. As compared to the exist ing phaseless measurement techniques, the use of two different probes makes it possible to avoid the need for a second scanning surface and thus allow s the use of smaller (and cheaper) anechoic chambers. Furthermore, the meas urement time is essentially equal to that required by conventional techniqu es based on the measurement of the complex near field. The reliability and the effectiveness of the approach are investigated and discussed and the ke y factors affecting its behavior are highlighted. In particular, the releva nce of the difference between the plane wave spectra (PWS) of the two probe antennas in ensuring an acceptable reliability of the solution, with respe ct to the starting point of the procedure, is outlined. Finally, the effect iveness of the approach is confirmed by an extensive numerical analysis, wh ich also shows the stability of the solution against noise on data.