Design and Calibration of Multi-Featured Large H-Coil Sensor Intended for 2D and Rotational Measurements

Dual H-coils are used for 2D and rotational measurements of magnetic field strength H. For precise measurements, they need to be constructed with a high level of orthogonality, which can be achieved by using a PCB (printed circuit board). This technology was employed for designing and manufacturing a multi-feature H-coil with the following functions: two sensing coils (X and Y) on the same large PCB substrate (165 mm diagonal), controlled orthogonality for each turn of the sensing coils, suppressed sensitivity to the H_Z component by eliminating the off-axis active area, thin former (0.75 mm nominal), sectioned design for accommodating B-coil wires so that the H-coil can be placed directly on the sample surface (demonstrated for the first time in the literature), stackable design enabling extrapolation of H towards sample surface, estimation of the order of magnitude of self-capacitance (demonstrated for the H-coils for the first time) and bandwidth (shown experimentally to hold up to 100 kHz), verification of sensitivity (calibration) in a long solenoid. Good agreement was obtained between sensitivity estimated from dimensions and from calibration (2% or better). The multiple features demonstrate the state-of-the-art collection of improvements as suggested separately in the literature before.