A Virtual Network Matching Method for Correcting Asymmetric Near-Field Probing System

In symmetric two-port probing system, the measured electromagnetic field signals can be decoupled. However, in practical application, asymmetric problem is difficult to avoid. So, correcting asymmetric probing system (APS) is significant to achieve ultra-wide-band near-field measurement. In this article, a virtual network matching method (VNMM) is proposed based on a circuit model, which is different from the previous asymmetric correction (or calibration) method. By setting up a virtual matching network, the APS is transformed into a virtual symmetric probing system (SPS), then the measured electromagnetic field signals can be decoupled. As a new forward correction method, the proposed VNMM is simpler and easier to use than the previous forward correction method. The measurement results of a two-port probing system in three asymmetric cases have verified the effectiveness of the VNMM, and a near-field scanning measurement proves the practical applicability of the VNMM. Furthermore, the VNMM can also be easily expanded to correct asymmetries of multiport probing systems.