A New Differential Composite Probe With Outstanding Advantages of High Sensitivity, Multiple Components, and Low Profile

In this article, a new differential composite probe with low-profile and high-sensitivity is developed. The proposed probe includes a U-shaped loop as a main element, a pair of U-shaped loops on the outermost layers and a pair of long U-shaped loops on the inner layers as parasitic elements, and two stripline terminated with two sub-miniature A (SMA) connectors. Traditionally, single-loop probes are used to sense electric- and magnetic-field components simultaneously. Here, two pairs of U-shaped loops are introduced as parasitic elements into a single-loop probe to enhance the amount of received electromagnetic signals. Moreover, these parasitic U-shaped loops on the inner layers of the probe are replaced with parasitic long U-shaped loops, thus significantly improving the detection sensitivity. Unlike the detection loops of traditional probes, which are all located on the inner layers, a pair of parasitic U-shaped loops, and the ground planes are printed together on the outermost layers in the proposed probe to reduce the probe’s profile. Because of this new design, the proposed probe only requires a five-layer printed circuit board (PCB) structure instead of a seven-layer PCB structure. A commercial high-frequency electromagnetic simulation software is used to design and simulate the proposed composite probe. A five-layer PCB structure is used to manufacture a prototype, and a self-developed near-field scanning test system with a standard microstrip line is utilized to characterize and calibrate the probe. As last, the simulation and measurement results are compared to verify the design rationality. The comparison results reveal that the designed differential composite probe has high detection sensitivity, a low profile, and the ability of measure electromagnetic-field components.