Sensor Architecture
Inductive pickup loops engineered for electromagnetic compatibility troubleshooting capture localized magnetic flux emissions generated by switching currents on printed circuit board assemblies. An h-field probe converts time-varying magnetic flux passing through its shielded coil into a proportional voltage signal routed to a spectrum analyzer or oscilloscope. By isolating magnetic fields from adjacent electric fields through balanced electrostatic shielding, the sensor maps circulating current loops around high-speed traces, power converters, and microcontrollers.
The physical geometry of the pickup aperture sets a trade-off between spatial resolution and sensitivity, as smaller loop diameters isolate microscopic trace paths but produce weaker coupling voltages at lower frequencies. The operational range ends when broad-spectrum electric field pickup overpowers weak magnetic flux signals at higher frequencies.
Diagnostic Execution
Diagnostic scanning maps emissions across board planes by holding the sensor tip perpendicular to signal traces and ground returns during full operational cycling. The h-field probe detects current crowding near split reference planes, decoupling capacitor loops, and unshielded inductor bodies where high di/dt events generate local electromagnetic hot spots. Swapping between small millimeter-diameter loops and larger centimeter loops allows an engineer to identify a general circuit zone before isolating an individual component pin.
Calibrated transfer impedance data curves convert measured receiver microvolts into absolute magnetic field strength across the target frequency band.
Verification Protocol
Acceptance testing evaluates common-mode rejection, probe factor accuracy, and spatial isolation using calibrated stripline fixtures and transverse electromagnetic cells. An unshielded h-field probe introduces electric field artifacts that misidentify component leads as major magnetic emission sources. Direct contact with uninsulated conductive traces risks grounding sensitive nodes or injecting external radio frequency noise into high-impedance receiver circuits.
Measurement repeatability requires robotic positioning stages to maintain consistent probe elevation and orientation across automated electromagnetic interference scanning tables.
