High Common-Mode-Rejection Magnetic-Field Probe Based on Differential Dual Loop and Integrated Balun

In this article, a magnetic-field probe with improved common-mode rejection ratio (CMRR) is proposed, fabricated, and calibrated. The magnetic-field probe consists of a differential dual loop (DDL) and an integrated balun. The advantage of this integrated design is to sense more magnetic flux and convert the differential signal into a single port signal, which makes the test easier. The CMRR of the proposed probe is more than 35 dB from 0.8 to 2.5 GHz under the condition that the loop size is 4.7 mm
$\times4.6$
mm. The probe is verified through the simulation, the comparisons with reference probes and the near-field measurement of a U-shaped microstrip line.