Measurement of complex near magnetic fields by using 6-port network

In order to investigate the generation and propagation mechanism of electromagnetic interference (EMI), near electro-magnetic (EM) fields have been measured. In many cases, magnitude of the fields is often measured. But if we can measure the fields in complex domain (magnitude and phase), we can get more information of EMI. we discuss the basic concept for the 6-port network used here, and then the network with 90° and 180° hybrid circuits are proposed. We compare the results by using the proposed network and by a vector network analyzer (VNA).