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Calculators / Coaxial Cable Loss
Coaxial Cable Loss
Calculator
Calculate coaxial cable attenuation, power loss, and signal level at the output for any cable type, frequency, and length. Essential for RF system design, antenna feed line analysis, and transmission line loss estimation.
Inner Conductor
Dielectric
Outer Shield
⚙ Coaxial Cable Loss Engine
Higher frequency → higher attenuation
Total run length including all bends
20 dBm = 100 mW typical transceiver output
LMR-400 selected: loss ≈ 1.5 dB/30 m at 100 MHz
Advanced Parameters
Active when “Custom” cable selected
dB
PL-259 ≈ 0.1–0.3 dB, N-type ≈ 0.1 dB, SMA ≈ 0.05 dB
Typically 2 (one each end). Add for barrel connectors.
°C
Loss increases ~0.1%/°C above 20°C for copper
Calculated Results
Total Cable Loss
—dB
Loss severity
—
Output Power (Pout)—
Output Power (dBm)—
Power retained—
Power lost (heat)—
Attenuation (dB/100 ft)—
Attenuation (dB/100 m)—
Cable loss only—
Connector loss—
Velocity Factor (VF)—
Impedance (Z₀)—
Electrical length—
Select cable type and enter values above.
📖 Theory
Coaxial cable attenuation (loss) has two components: conductor loss (∝ √f) and dielectric loss (∝ f). Together they determine total signal loss per unit length.
Attenuation vs Frequency
α(f) = A·√f + B·f
A = conductor loss coefficient, B = dielectric loss coefficient. f in MHz.
Total Loss
Loss(dB) = α · L + N·Lc
α = dB/m at frequency f, L = length (m), N = connectors, Lc = connector loss.
Output Power
Pout(dBm) = Pin(dBm) − Loss(dB)
Pout(W) = Pin · 10^(−Loss/10)
As a rule of thumb: every 3 dB of loss halves the power. 10 dB loss = 90% of power dissipated as heat in the cable. Keep feed lines as short as possible and use the lowest-loss cable that fits your budget.
📊 Loss vs Frequency & Length Viewer
Live Charts
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◉ Loss curve updates with cable selection
Chart Type
Length
10 m
1 m200 m
Max Freq
1000 MHz
Loss (dB) vs Frequency
ℹ
Feed Line Design Insights
Select a cable type and enter your frequency and length to see design insights.
Common Applications
RF System Design
Calculate total signal budget including transmitter, cable loss, and receiver sensitivity to ensure link margin.
Antenna Feed Line
Size the coax run from transceiver to antenna. Minimise loss — every dB lost in the cable wastes transmit power and degrades receive sensitivity.
TV / CATV Distribution
RG-6 and RG-59 attenuation for cable TV signal distribution. Determine if amplifiers are needed for long runs.
Test & Measurement
Cable loss in test setups affects measurement accuracy. Calibrate out cable loss when measuring antenna gain or signal levels.
Get "10 RF Design Principles Every Engineer Should Know" Free
Learn practical principles for better RF circuits, PCB layouts, simulations, measurements, and troubleshooting.