Advanced Coax Cable Loss Calculator

Coax Cable Loss Calculator Form

Use the responsive input grid below. It displays three columns on large screens, two on smaller screens, and one on mobile.

Operating Frequency

Signal frequency used for the run.

Frequency Unit

Choose MHz or GHz.

Cable Length

Physical cable length for the path.

Length Unit

Choose meters or feet.

Reference Attenuation

dB at the reference frequency and length.

Reference Length

Vendor attenuation table reference length.

Reference Length Unit

Match the attenuation reference sheet.

Reference Frequency

Frequency paired with reference attenuation.

Reference Frequency Unit

Choose MHz or GHz.

Frequency Scaling Exponent

Typical empirical range is 0.5 to 1.0.

Connector Loss Each

Loss per connector, adapter, or jumper interface.

Connector Count

Total number of interfaces in the path.

VSWR

1.0 means ideal match and zero mismatch loss.

Temperature

Ambient cable temperature in °C.

Temp Coefficient per 10°C

Percent change in attenuation per 10°C from 20°C.

Safety Margin

Optional design margin added to total loss.

Input Power

Transmitter power at the cable input.

Input Power Unit

Choose watts or dBm.

Sweep Minimum

Lower frequency for the graph sweep.

Sweep Maximum

Upper frequency for the graph sweep.

Sweep Unit

Use the same unit for min and max sweep values.

Reset

Example Data Table

This sample mirrors a typical RF feeder estimate using the default values from the calculator.

Input Item	Sample Value	Output Item	Sample Result
Operating Frequency	900 MHz	Base Cable Loss	6.261 dB
Cable Length	30 m	Temp-Adjusted Cable Loss	6.336 dB
Reference Attenuation	22 dB per 100 m at 1000 MHz	Connector Loss	0.300 dB
VSWR	1.20	Mismatch Loss	0.036 dB
Input Power	100 W	Total Loss	7.172 dB
Safety Margin	0.50 dB	Output Power	19.17 W

Formula Used

1) Base cable attenuation model

Cable Loss (dB) = Reference Attenuation × (Operating Frequency / Reference Frequency)ⁿ × (Cable Length / Reference Length)

2) Temperature adjustment

Temp Factor = 1 + ((Temperature − 20) / 10) × (Temperature Coefficient / 100)
Adjusted Cable Loss = Base Cable Loss × Temp Factor

3) Mismatch loss from VSWR

Reflection Coefficient, Γ = (VSWR − 1) / (VSWR + 1)
Mismatch Loss (dB) = −10 × log₁₀(1 − Γ²)

4) Total loss and output power

Total Loss = Adjusted Cable Loss + Connector Loss + Mismatch Loss + Safety Margin
Output Power = Input Power × 10^{(−Total Loss / 10)}

This model is practical and engineering-friendly. It combines vendor attenuation data with scaling, temperature, mismatch, and connector penalties for a realistic field estimate.

How to Use This Calculator

Enter the operating frequency and cable length for your run.
Enter the attenuation value from your cable datasheet.
Match the reference frequency and reference length from that datasheet.
Set the scaling exponent. Use 0.5 for many common approximations.
Add connector count, loss per connector, and VSWR.
Apply temperature correction and any design safety margin.
Enter transmitter power in watts or dBm.
Choose the sweep range for the Plotly chart.
Press Calculate Loss to display the result above the form.
Use the CSV and PDF buttons to export your summary.

FAQs

1) What does this calculator estimate?

This tool estimates coaxial line attenuation, connector loss, mismatch loss, total insertion loss, delivered power, voltage ratio, and loss trends across frequency.

2) Why is a reference attenuation value required?

Most cable datasheets publish attenuation at a known frequency and length. The calculator scales that known point to your operating condition.

3) What scaling exponent should I use?

Use the exponent recommended by your modeling method or cable family. A value near 0.5 is a common approximation when conductor loss dominates.

4) Why include connector loss separately?

Real installations often include adapters, bulkheads, and jumpers. Even small connector losses add up and can materially change the final link margin.

5) What does VSWR change in the result?

VSWR introduces mismatch loss. It represents power reflected by imperfect impedance matching, reducing the power delivered beyond cable attenuation alone.

6) Does temperature really matter?

Yes. Cable attenuation usually rises with temperature. Long runs, warm rooftop installations, and outdoor enclosures can create noticeable extra loss.

7) Is the result exact for every cable type?

No. It is an engineering estimate. For final design work, compare with manufacturer data, measured insertion loss, and full link-budget verification.

8) What does the Plotly graph show?

The graph shows estimated total loss versus frequency over your chosen sweep range, helping you see how attenuation grows across the band.