An Ultra-Wideband Electric Field Probe With High Sensitivity for Near-Field Measurement

An ultra-wideband electric field probe with high sensitivity is proposed for near-field measurement. It consists of the coupling part, the transmission part, and the output part. In the coupling part, the L-shaped tip and the loaded sensing via are designed to improve the sensitivity. In the output part, the horizontal gradual substrate integrated coaxial line (SICL) to grounded coplanar waveguide (GCPW) transition is designed for good field and impedance matching, resulting in a wide bandwidth. In addition, the equivalent circuit is established to explain the mechanism of sensitivity improvement and optimize the performance of the proposed probe. The proposed electric field probe is made with a printed circuit board (PCB) process and applied to measure the electric near field. The measurement results show that the electric field probe has a bandwidth from 10 MHz to 60 GHz and a spatial resolution of 0.7 mm. In addition, the sensitivity of the proposed electric field probe is about 12 dB higher than that of the conventional monopole electric field probe at the same size as the coupling part.