Four-Port Probe for Simultaneous Measurement of Electric and Magnetic Fields in Near-Field Scanning

In this article, a symmetric probe with four ports is proposed for ultrawideband and simultaneous near-field measurement of ${H} _{x}$ and ${H} _{y}$ (along the horizontal direction of the probe) and ${E} _{z}$ (along the normal direction of the probe) components from 0.01 to 15 GHz. The probe incorporates four meticulously designed symmetrical loops, created from vias and traces within a four-layer printed circuit board (PCB), which serve the purpose of detecting radio frequency (RF) electric and magnetic fields. Due to the symmetric design, three orthogonal electromagnetic field components ( ${H} _{x}$ , ${H} _{y}$ , and ${E} _{z}$ ) can be extracted by common and differential calculation of the four signal outputs of the probe. A near-field scanning apparatus, integrated with a microstrip line, is used to characterize the performance of the electromagnetic field probe in application. To further verify the ultrawideband and simultaneous near-field measurement of ${H} _{x}$ , ${H} _{y}$ , and ${E} _{z}$ , the near-field scanning is meticulously executed on a Z-type microstrip interconnect, meticulously capturing the three-surface electric and magnetic fields. The measurement results are validated in simulation. Therefore, the designed ultrawideband probe has excellent features in wideband operation, multicomponent measurement ( ${H} _{x}$ , ${H} _{y}$ , and ${E} _{z}$ ), and electric-field suppression in near-field scanning, which can improve testing efficiency and reduce rotational measurement errors in actual electromagnetic interference (EMI) identification.