Coax Comparison Calculator

Quick instructions: lookup (somewhere else) the cable attenuation for a given frequency for your current cable and a better one. Insert the cable length you need, press the Compute button. The calculator gives correct results if all values are referred to feet rather than metres.

Worst cable data

Loss at desired frequency: [dB] every [m]

Best cable data

Loss at desired frequency: [dB] every [m]

Common attenuation values

  • RG58: 20 dB/100m @ 144 MHz
  • RG213: 8.2 dB/100m @ 144 MHz
  • Aircom+: 4.5 dB/100m @ 144 MHz
  • Cellflex 5/8": 2.5 dB/100m @ 144 MHz
  • Cheap CATV 75ohm: 8.9 dB/100m @ 200MHz


Cable length: [m]


Worst cable attenuation: [dB]
Best cable attenuation: [dB]
Pure cable attenuation difference: [dB]

An example. 75 ohm cable between 50 ohm systems causes an SWR of 1.5:1, which equals to 0,13 dB loss.
If the best cable described above "is" 75 ohm and RTX+antenna "are" 50 ohm, the actual improvement can be estimated as [dB].

Remember: 3 dB means half power.

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Page created by Paolo Cravero © IK1ZYW - Aug.2005

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