A simple miniature magnetic-field probe for near-field measurements in 9-kHz-20-GHz bandwidth, which is applied to highspeed circuits, has been proposed and manufactured. The magneticfield probe is built on a four-layer printed circuit board (PCB) using high-performance and low-loss Rogers material (ε _r = 3.48 and tan δ = 0.0037). Electric field coupling can be suppressed by PCB shielding structure of the magnetic-field probe. Coax-thru-hole via array technique is used to achieve impedance match. The resonance in working frequency band is suppressed through via fence, making |S ₂₁ | rather smooth in the operation band. Experimental results show that the working frequency band is up to 9 kHz-20 GHz.

In this communication, a magnetic field probe with high common-mode rejection ratio (CMRR) and high sensitivity for the near-field measurement is proposed, fabricated, and calibrated. The proposed magnetic field probe consists of a differential dual loop (DDL) to improve the CMRR to the electric field, a balun to convert the differential end to the single end, and a two-stage amplifier achieving proper gain to further enhance the sensitivity. The sensitivity of the probe is raised by more than 50 dB at 30 MHz compared with the reference probes. The measured CMRR is more than 40 dB from 200 kHz to 1 GHz. The measurements of the passive circuits are conducted, and validating that the sensitivity of the proposed probe is significantly improved.

The designs of two resonant electric-field probes with improved sensitivity for near-field measurements are proposed and measurements in weak radiated level are conducted. One probe is the resonant monopole probe and the other is named the resonant T-shaped probe with further improved sensitivity. Each of the two probes is fabricated on four-layer printed circuit board using high-performance and low-loss Rogers material (ϵ r = 3.48 and tanδ = 0.0037), which consists of an LC resonator made up of a planar spiral stripline (inductor) and a rectangular plate (capacitor), a single-stub transformer, and a SubMiniature version A connector. The LC resonator can achieve a specific resonant frequency for a specific narrowband of interest with the pure input resistance. The single-stub transformer is used to transform the pure input resistance to the input impedance of measurement instruments to acquire maximum transmission power. Compared with the referenced broadband probe with the same physical size of tip, the measured | S₁₂| of the resonant monopole probe is enhanced by 9 dB at the resonant frequency. The resonant T-shaped probe proposed has 3.3-dB sensitivity higher than the resonant monopole probe in terms of | S₁₂| . In order to validate the improved sensitivity of the resonant probes, comparisons on the improvement of sensitivity with other probes are also introduced.

This paper develops an improved noncontact current probe for locating the noise source to estimate the electromagnetic interference emission on printed circuit board (PCB). The miniature current probe is fabricated in a four-layer PCB with high-performance dielectric RO4003C. The designs of isolated via array and matching via-pad structures are used to optimize the performance of probe. The probe can then be used for wideband electromagnetic compatibility test from 9 kHz to 10 GHz under narrow and complex conditions. The current probe can be sensitive enough to detect the weak current signal as small as -130 dBA and has a spatial resolution of 1 mm. The application of current probe in noise location on PCBs based on measured surface scan method is investigated in this paper. And two near-field measurement results compared with the reference probe are used to illustrate the new features of the probe.

In this paper, a high-sensitivity resonant probe for capturing tangential E-field component is fabricated on a four-layer PCB. The resonant probe consists of improved dipole employed to further enhance sensitivity, a resonator made up of open-and short-circuit stub achieving specific resonance, and an integrated Marchand balun used to transform the differential -mode voltage to the single-end output and match the instrument port impedance match. Compared with the referenced broadband probe, the relative sensitivity of the proposed resonant probe in terms of |S12| is enhanced by 13.21 dB and 14.82 dB for simulation and measurement, respectively. The absolute sensitivity in terms of the noise equivalent field strength (NEFS) is 26.4dBμV√Hz.The measurements of the passive circuits (microstrip lines and coupled lines) and active circuit module are conducted to validate the resonant probe.

A normal component electric probe with miniature size and ultrawideband characteristic is proposed in this paper. The probe is fabricated in a four-layer printed circuit board (PCB) with high performance dielectric RO4003C and RO4450. The minimum width of the probe is 4mm and the length of probe is 48mm. The probe can be used in compact and complex space like PCB and integrated circuit (IC). The designs of U-shaped structure and tuning element matrix are used to expand the work band and optimize the impedance of signal via. The work band of probe can cover from 9 kHz to 40 GHz. It can improve the test efficiency in ultrawideband application compared with series probe. The sensitivity of the probe is higher about 12dB than commercial probe above 1GHz, and the spatial resolution is 1mm when the height of probe is 0.3mm. The proposed probe is verified with simulation in full wave tool and measurement.