Cable Loss Frequency Scaling (√f Approximation)
Estimate cable loss at another frequency from one known point using a √f approximation.
Worked example
Input: Loss at reference freq. 0.3 dB/m, Reference frequency 100 MHz, Target frequency 1000 MHz, Cable length 5 m
Result: Loss at target freq. 0.948683 dB/m, Total loss 4.74342 dB
Result: Loss at target freq. 0.948683 dB/m, Total loss 4.74342 dB
Formula
α(f) ≈ α_ref · √(f / f_ref)
Total loss = α(f) × length
How it works
Coax attenuation grows with the square root of frequency where conductor loss dominates. When a datasheet lists only a few frequencies this lets you roughly estimate the loss in between.
Practical tipAt higher frequencies dielectric loss (proportional to frequency) adds on top, so actual loss exceeds the √f estimate. For test corrections always use a loss table measured with a network analyzer.
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Results and summaries are for reference. For certification and test reports use the latest official standard text and calibrated instrument data. Last updated: 2026-10-10