Coax impedance and attenuation estimate calculator

Cable loss at supplied per-length attenuation; connectors included separately.

rf-coax.napkin / editable

SCENARIO COMPARISON

Compare the numbers.

This source describes an analytical model. Its quantities and checks are the view.

Scenario	lossDb	powerFraction
	2	0.630957
	1.8	0.660693

All calculated quantities are listed with the inputs. Switch to Source to inspect the equations.

SCENARIOS / CALCULATED VALUESSAME SOURCE

Change an input to see the consequences.

loss budget in dB2.00 ✓ passes

BASELINE INPUTS

length5 mattenuationPerMetre0.2 m^-1connectorLossDb1

CALCULATED

lossDb2

powerFraction0.63096

Edits change the baseline source.

THE SOURCE

Edits below update the same model.

# Coax impedance and attenuation estimate
# Scope: Cable loss at supplied per-length attenuation; connectors included separately.
# Status: illustrative worked example; engineering review pending.
# Inputs are example values. Checks are editable example requirements, not standards.

length = 5 m
attenuationPerMetre = 0.2 m^-1
connectorLossDb = 1

lossDb := attenuationPerMetre*length+connectorLossDb
powerFraction := 10^(-lossDb/10)

check loss budget in dB: lossDb <= 3

scenario alternative: length = 4 m

Calculated from your source · not saved

Baseline · Baseline

loss budget in dB2.00 ✓ passes

alternative · alternative

loss budget in dB1.80 ✓ passes

Illustrative first-order example. Checks are editable requirements, not design standards. The broader topic may require additional equations, data, and validation.

Formula and units

This example uses the following equations. Input names and units match the editable source above.

loss db: lossDb = attenuationPerMetre*length+connectorLossDb
power fraction: powerFraction = 10^(-lossDb/10)

Original worked example

These are the baseline values in the downloadable source. Edits above let you test your own values.

Given

length: 5 m
attenuation per metre: 0.2 m^-1
connector loss db: 1

Calculated

loss db: 2
power fraction: 0.630957

Assumptions and limits

Cable loss at supplied per-length attenuation; connectors included separately.

The requirement checks use the limits written in this example. Passing a check does not establish that the model covers every load, material behavior, or operating condition in a real design.

Download this .napkin example ↓

Take it further with your agent

Napkin keeps the inputs, equations, checks and assumptions together in one study. Your agent sets it up; you change the numbers.

Try with Claude ↗

codex 'Use Napkin (https://napkin.engineering/mcp, or the local Napkin plugin) to build a study: Coax impedance and attenuation estimate. Inputs: conductor/dielectric geometry; material; frequency. Outputs: nominal impedance; conditional loss. Model scope: Link and transmission models with declared propagation assumptions. Read napkin_capabilities and the current snapshot. Ask me for the values that matter, label assumptions with units, author .napkin source, validate it and apply it with napkin_source using the current revision, then open the study. Add checks for the limits I supply. Keep unsupported analyses explicit.'

Claude needs the Napkin connector; Codex needs the Napkin plugin. Set up your agent ↗

The broader study

The topic brief below describes the broader scope. The worked example above states the particular calculation it implements.

Inputs: conductor/dielectric geometry, material, frequency
Outputs: nominal impedance, conditional loss
Modes: calculate, compare, sweep
Drawing: Link-budget and coverage plots

EXECUTABLE WORKED EXAMPLE · FIRST-ORDER MODEL · CHECK THE SCOPE & ASSUMPTIONS