An Ultrawideband Magnetic Near-Field Probe with a High Spatial Resolution Based on the Horizontal Transition Structure

In this paper, an ultrawideband magnetic near-field probe with a high spatial resolution based on the horizontal transition structure, which is stripline (SL) to spoof surface plasmon polariton (SSPP) transition, is proposed. In the induction part, the loop aperture is designed to enhance the spatial resolution. The shield metal sheets are introduced to improve the electric field suppression ratio (EFSR). In the transmission part, the horizontal transition with a tapered slot is introduced for impedance and field matching to obtain ultrawide bandwidth. In the head part, the SSPP structure is designed to expand the bandwidth and improve the immunity to external interference. The proposed magnetic field probe is fabricated by the printed circuit board (PCB) process, then applied to the magnetic field distribution measurement. The measurement results agree with simulation results very well, which show the bandwidth is from 100 MHz to 55 GHz and the spatial resolution is 0.8 mm at 10 GHz and 0.5 mm at 50 GHz.