Measure voltage along a field path

Use circuit.integrate_E to read a voltage along a declared path from a recorded electric field. A time-domain frame gives a real voltage; a frequency-domain frame gives a complex voltage phasor. A phasor retains its magnitude and phase without selecting a real snapshot first.

Record the complete path

Add a MonitorFieldFrequency that records fields=["E"] over a region containing the entire path, then run the analysis. The following recipe assumes the monitor is named gap, records 5 GHz, and spans the example 7 mm path. The same access works for a result loaded from a project:

import numpy as np
from magnelio import circuit, geo

field = result.monitors["gap"].spectrum.at_frequency(5e9)
path = geo.Curve.polyline([(0.0, 0.0, 0.0), (7e-3, 0.0, 0.0)])
voltage = circuit.integrate_E(field, path, field.grid)

magnitude = abs(voltage)
phase_deg = np.angle(voltage, deg=True)

For a uniform Ex = 3 + 4j V/m along this path, the result is 0.021 + 0.028j V: magnitude 35 mV and phase about 53.13 degrees. Reversing the two points negates the phasor. For a real time recording, select a frame with monitor.recording.at_time(t) and pass that field in the same way.

Interpret the result

The field is in physical V/m, not the solver’s edge-voltage units. Always use the selected frame’s own grid, especially for a monitor covering only part of the model. Frequency frames normalized per sqrt(watt) give a voltage per sqrt(watt); a field scaled to a physical excitation gives the corresponding physical voltage. Integration does not change the recording’s normalization.

The direction defines the sign of integral E dot dl. This is a path measurement, not a path-independent voltage between arbitrary points in a time-varying magnetic field. The rasteriser snaps endpoints and follows grid edges; keep the whole path inside the recorded region and resolve the geometry adequately. A path shorter than the grid can resolve is rejected. See Edge-path rasterisation for the discretization and phase convention.