Phase Resolved near Field Dipole Reconstruction for Multilayer Board Far Field Escape Prediction
Phase-resolved near-field dipole reconstruction predicts far-field escape emissions within 2 dB, eliminating un-phased scan errors before SAC testing.
Spatial Resolution Limit
Measurement Boundary
Physical constraints define the minimum separation required between two distinct features or field sources to resolve them individually. The spatial resolution limit determines the minimum distance between two high-frequency currents on a printed circuit board that can be distinguished by a near-field scanner. This limit is dictated by the size of the probe and its distance from the board surface during the scan.
The boundary of this limitation is governed by the physics of evanescent waves, which decay rapidly with distance from the source.
Scanning Optimization
Scan parameters in electromagnetic compatibility testing are selected based on this physical boundary to balance scan time and feature detail. When a scanner is positioned too far from the board, the spatial resolution limit prevents the localization of individual trace emissions, causing adjacent traces to appear as a single broad source. To resolve individual traces, the probe height must be reduced to a fraction of the trace spacing, and the scan step size must be adjusted accordingly.
This adjustment increases the number of data points and the total scan time. The choice of scanning height is a trade-off between the need to resolve fine trace details and the risk of physical collision between the probe and tall board components.
Detail Verification
Verification of scan detail compares the output image with the physical board layout. If the measured hotspots cannot be matched to individual traces, the scan height must be decreased to improve the spatial resolution. This step ensures that the diagnostic data is precise enough to guide board modifications.