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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${H} _{x}$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${H} _{y}$ </tex-math></inline-formula> (along the horizontal direction of the probe) and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E} _{z}$ </tex-math></inline-formula> (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 (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${H} _{x}$ </tex-math></inline-formula>, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${H} _{y}$ </tex-math></inline-formula>, and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E} _{z}$ </tex-math></inline-formula>) 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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${H} _{x}$ </tex-math></inline-formula>, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${H} _{y}$ </tex-math></inline-formula>, and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E} _{z}$ </tex-math></inline-formula>, 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 (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${H} _{x}$ </tex-math></inline-formula>, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${H} _{y}$ </tex-math></inline-formula>, and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E} _{z}$ </tex-math></inline-formula>), and electric-field suppression in near-field scanning, which can improve testing efficiency and reduce rotational measurement errors in actual electromagnetic interference (EMI) identification.