A proficiency testing framework for RF-EMF measurements of mobile communication base-station-like sources in uncontrolled environments

• A frequency-swept reference item broadens RF-EMF PT beyond tone and comb sources. • The D′ rule combines a preset ±3 dB tolerance with assigned-value uncertainty. • Synthetic-offset crossings occur at +3.42 to +3.78 and −4.81 to −3.92 dB. • Robust-distance and LOF screening identify unusual inter-laboratory patterns. • Inter-laboratory dispersion increases at medium and longer distances. This study evaluates an engineering method chain for proficiency testing of broadband radiofrequency electromagnetic field (RF-EMF) measurements in mobile-communication bands at uncontrolled participant sites. The method chain comprises a transportable reference item, standardized test layout and procedure, sample stability verification, data distribution testing, robust statistical processing, and engineering-based main evaluation. Measurements from 15 laboratories used the 4G/Wi-Fi and 5G source configurations at 1.0 m, 1.5 m, 2.0 m and 3.0 m, with the 6-min total broadband root-mean-square (RMS) field as the measurand. Robust statistics were used to determine assigned values, and the D′ structure adapted from quantitative electromagnetic compatibility (EMC) proficiency testing was used as the main evaluation method, supplemented by z-score, E n where calculable, and multivariate screening. Based on measurement data from 15 laboratories, the results showed that the reference item remained stable throughout the proficiency testing period. Under the D′ criterion, all 15 laboratories were rated satisfactory. The dispersion of results among laboratories was generally higher at medium and long distances. Multivariate analysis identified a small number of laboratories for follow-up rather than changing their formal proficiency-testing status. A post hoc ±1 to ±4 dB sensitivity analysis showed no status change at ±3 or ±4 dB, one laboratory changing at ±2 dB, and six at ±1 dB. The framework applies to the defined fixed-point broadband measurand and does not reproduce LTE/NR modulation, spatial-maximum searches, or the operational stand-off distances of a live base station.