Mapping a coil's near field
A walkthrough of the first near-field scan — hardware setup, raw results, and what the noise looks like.
Chapters
- Setup and motivation
- Probe hardware and positioning stage
- First scan and raw data
- Filtering and comparison to Biot-Savart
- Next steps
Parts
- Small loop probe (hand-wound, 5mm diameter)
- NEMA 17 stepper motors2
- Linear rail (200mm)
- AD8307 log amplifier
The mapper’s first real test: scanning the near field of a planar coil and comparing the result to the analytical Biot-Savart solution. The video covers the probe hardware, the positioning stage, and what the data looks like before and after filtering.
The scan takes about twenty minutes for a 40x40 grid at the current step rate. That is slow, but the point right now is correctness rather than speed. The field shape is recognizable and the peak is where it should be.