Analytical Probe Factor Models for Rectangular Loop Probes Used in Near-Field Measurements

In this article, analytical probe factor models for rectangular loop probes are proposed. In order to calculate the probe factor using a microstrip line, two magnetic field equations and four induced voltage equations are derived according to the size of the probe loop, the width of the microstrip line, and the distance between the probe and the line. The accuracy of the proposed models is verified by comparing them with a three-dimensional full-wave simulation and measurement results. In addition, the concepts of mechanical and electrical heights are analytically defined from the relationship between the induced voltage and the near magnetic field. It is confirmed that a unique probe factor regardless of the measurement height can be extracted using the proposed electrical height.