Whitepaper
Problems That Can Arise in a Working EMC Laboratory and How Pre Test Verifications Can Help
This white paper from Eurofins York EMC Services, authored by Dave Cullen and Mark Anslow, examines the practical challenges that can compromise measurement quality in a working EMC test laboratory and makes the case for systematic pre-test verification. The paper identifies four main categories of risk: equipment failure (including physical damage to RF connectors, electrical damage from transients, and performance degradation through normal ageing), inconsistency and repeatability issues arising from reconfigured test chambers or changing environmental conditions, equipment operating outside its calibration specification in ways that standard recalibration may not catch, and human error from incorrect settings, procedural gaps, or outdated test standard implementations. Each problem is illustrated with real examples, such as a faulty mains power supply introducing voltage oscillations larger than the flicker disturbance being measured, contaminated connectors at an Open Area Test Site causing rippled frequency responses, and a receiver exhibiting stepped anomalies of up to 4 dB that fell within the manufacturer's published specification. The paper then outlines how pre-test verification using reference signal sources can detect these issues before they affect results. It compares broadband noise sources, which provide continuous spectral coverage and are effective at revealing frequency-dependent faults and verifying detector and bandwidth settings, against comb (harmonic) generators, which offer discrete frequency components useful for checking frequency and amplitude accuracy. The conclusion is that a layered approach combining robust procedures, trained personnel, and regular pre-test checks against a stable reference baseline is essential for maintaining confidence in EMC test results.