Meaning
Loss of signal power along a coaxial transmission line represents a fundamental reduction in high frequency voltage during measurement sweeps. When routing signals from a test antenna to a receiver, cable attenuation decreases the signal level that reaches the detector. This loss is frequency-dependent and increases as the frequency of the measured signal climbs.
Power Reduction
Dielectric heating and conductor losses are the main drivers of signal degradation. High quality cables use double shielding and low density polytetrafluoroethylene to limit cable attenuation. In high frequency testing, the total path loss must be documented and mathematically compensated.
If the attenuation is too high, weak emission signals can fall below the noise floor of the instrument.
Temperature Variation
Environmental conditions in the test bay affect the physical properties of the conductor and dielectric. Increases in temperature cause cable attenuation to rise, which requires laboratory control or dynamic correction.
Testing Protocol
Calibration procedures require a regular vector network analyzer sweep of all test lines. This routine sweeps the cables to capture the insertion loss across the entire operating band. Handover documents contain the resulting correction table, which the automated measurement software uses to adjust the final dataset.
Cable replacements must trigger a recalculation of this path correction factor. Using a cable without its matched loss profile will directly compromise the validity of the compliance report.
