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 HZ 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.