A New Resonant Composite Probe for Near-field Scanning

In this article, a new wideband resonant probe with two orthogonal magnetic-field measurement features is proposed. The resonant magnetic-field probe consists of two orthogonal shorted sensing loops, two transmission lines with two outputs, a pair of LC resonant circuits, a shorted via, a connected via, and two rows of coaxial via fences. The LC resonant circuits including a pair of shorted stubs as additional inductor and open stubs as additional capacitor are used to excite resonant mode. The connected and shorted vias are used to form the orthogonal sensing loops. In order to verify the design rationality, the proposed probe is optimized, manufactured, and measured. The simulated results reveal the proposed probe could simultaneously test two orthogonal magnetic-field components at 1.575 GHz.

I. Introduction

In the radio frequency electronic systems, unknown electromagnetic interference (EMI) problems have become a key issue restricting its development. Usually, the near-field scanning technology is considered as an effective means that recognizes the unwanted radiation source [1] - [5]. However, if the EMI signal is lower than noise floor of the probe, it would be not sensed by the probe. Therefore, it is meaningful to develop a new probe with high sensitivity.