A Composite Probe With Parasitic Elements for Improving Sensitivity and Simultaneously Measuring Electric and Magnetic Fields

In this study, a composite probe with high sensitivity for the simultaneous measurement of electric and magnetic fields is proposed. Unlike the conventional composite probes, which have only one U-shaped loop, the composite probe consists of a U-shaped loop as the driven element, two pairs of U-shaped loops as parasitic elements, two connected vias, and two rows of grounded vias. First, the U-shaped loop serving as the driven element is terminated using two outputs to measure the electric and magnetic fields, simultaneously. Second, two pairs of U-shaped loops functioning as parasitic elements are introduced into the composite probe enable it to sense more electromagnetic signals. Third, two connected vias are used to connect the driven element and the parasitic element. Forth, two rows of grounded vias are utilized to suppress undesired parallel-wave modes. In addition, the detection principle, sensitivity enhancement principle, and evolutional probes models are given to explain the working mechanism. The near-field scanning system is used to characterize the composite probe. Finally, the composite probe is simulated, manufactured, and measured to demonstrate the design rationality. Furthermore, the transmission coefficient, calibration factors (CFs), spatial resolution (SR), and electric-field rejection ratio are given and discussed. The measured results reveal that the proposed composite probe has a higher sensitivity due to the existence of the parasitic loops, has a higher electric-field rejection ratio due to the existence of the U-shaped loop, and can simultaneously test the electric- and magnetic-field components.