Calibration of Magnetic Near-field Probes Based on the Helmholtz Coils

This letter proposes a structure designed based on the Helmholtz coils for calibrating magnetic near-field probes. For the traditional calibration methods, the inherent position sensitivity issues of the probes, stemming from their physical structure, necessitate the procedures to be more complex. Therefore, designing a new probe calibration structure is necessary to obtain the accurate probe factor quickly. Utilizing Helmholtz coils, a rectangular calibration device has been designed to ensure a uniform distributed magnetic field at its center plane to reduce the influence of the non-uniformity of the magnetic field on the probe factor. Finally, the calibration device is fabricated and tested, and the probe factors of the magnetic near-field probes are obtained. Upon comparison with the calibration data provided by the probe manufacturer, the probe factor obtained through the proposed calibration structure exhibits a high degree of consistency with the manufacturer's data. This indicates that the proposed structure can calibrate magnetic near-field probes within 1 MHz - 3 GHz, thus demonstrating its feasibility and accuracy during the calibrating procedure.