Meaning
Total electromagnetic attenuation across a test facility path incorporates cable losses and antenna factors. Compliance test laboratories measure site insertion loss to normalize radiated emission and immunity test results. This reference metric establishes the baseline loss between signal generator output ports and receiver input ports across a physical test site.
Scope covers open-area test sites, fully anechoic chambers and reverberation chambers.
Path Attenuation
Coaxial cabling and interconnect switches contribute predictable frequency-dependent loss to the measurement path. Determining site insertion loss requires subtracting known cable attenuation from raw transmission measurements. Environmental stability inside test chambers prevents temperature-induced phase drift in long RF cable runs.
Calibration Protocol
Annual site validation protocols utilize reference dipole antennas positioned at standardized heights and distances. Automated frequency sweeps capture site insertion loss data across broad spectrum allocations. Vector network analyzers measure complex transmission coefficients between transmitting and receiving antenna ports.
Physical surface imperfections on chamber walls create local reflection anomalies that show up as ripples in frequency response curves. Calibration software stores path correction factors in reference tables used during device qualification runs. Test engineers verify site stability by comparing current calibration curves against historical baseline profiles.
Compliance Margin
Measurement uncertainty calculations combine site loss calibration errors with instrument tolerances. Accurate site insertion loss values ensure certified device emission levels remain compliant with regulatory standards. Formal test reports include calibrated site loss curves attached to official accreditation filings.
