Probe Correction Technique of Arbitrary Order for High Accuracy Spherical Near Field Antenna Measurements
Probe correction in standard spherical near field measurements are typically limited to probes with |μ|=1 spherical wave spectrum when performing spherical wave expansion. The design of such probes is often a trade-off between achievable performance, modal purity and bandwidth. Compensation techniques for probes with higher or full order modal spectrum have recently been proposed. The advantages of such techniques are more freedom in the selection of the probe for a given measurement scenario and increased bandwidth. The technique reported in this paper is valid for probes with a known modal spectrum of arbitrary order. Probe compensation is performed directly on each spherical wave function before expanding the measured field. This leads to a computationally very effective algorithm. In this paper, the accuracy of the new algorithm is validated experimentally for different higher order probes in the measurement of a standard gain horn. For each scenario, the accuracy and computational requirement of the new algorithm is compared to standard transformations.