A Compact Low-Cost Wideband Shielded-Loop Probe With Enhanced Performance for Magnetic Near-Field Measurements

In this article, a compact low-cost wideband planar shielded-loop probe with enhanced performance is proposed for magnetic near-field measurements. The probe is designed based on a stripline structure and fabricated on an FR4 printed circuit board with a four-layer stack-up structure. In the proposed design, an inverted G-shaped inductive folded line is arranged on an added layer to increase the sensitivity to the magnetic field response. The sensitivity, in terms of |S
₂₁
|, of the proposed magnetic near-field probe is improved relative to the conventional shielded-loop by an average of 5 dB over the frequency band ranging from 100 MHz to 6 GHz. Also, two additional techniques to enhance the electric field suppression capability of the planar shielded-loop probe are presented: repositioning the short via hole and mounting a metal can on the probe.