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In this paper, systematic characterization of the dual probe, which is designed for the near field simultaneous measurement of both electric and magnetic field, is investigated with a microstrip line as the device under test (DUT). The characterization includes frequency response, transmission performance, symmetry, reflection, the intrusion of probe to the DUT, isolation of electric and magnetic field responses, field profile and spatial resolution, and differential electric field suppression. The dual probes with different design are adopted to demonstrate the systematic characterization.

To measure the magnetic near field with high common-mode noise rejection, a probe with the differential and symmetrical structure forming a detection loop is developed. Such measurement is performed by using a two-port vector network analyzer (VNA) and validated by using a microstrip line as a device under test (DUT). In comparison to the measurement with traditional single-output magnetic near field probe, the electric field suppression of the proposed measurement can be improved by at least 10 dB in the frequency range of $3\sim 11$ GHz, while the other characteristics remain unchanged.

This paper presents a noncontact radio frequency voltage sensing of a printed trace by using a capacitive-coupled probe. The noncontact voltage sensing is demonstrated by using an open-end coaxial probe, and achieved through the transfer factor from the printed trace to the probe and a reconstruction algorithm. To validate the voltage sensing, known periodic, and pulse voltages are injected into the printed trace and compared with the reconstructed waveforms. Our results demonstrate that the voltage sensing method can be used for measurement of a random waveform with period even down to 1 ns and single pulse with rise time down to 2 ns. In consideration of the flexible relocation of the probe, the voltage sensing accuracy caused by spatial errors is also investigated.