VSWR calculator

Power measurements:

Transmitter power output into nominal load (W):

Forward power (W):


Other measurements / estimates / details:

Line loss to transmitter (dB):

Line loss to antenna (dB):

Antenna gain (dBi):



  70cm 35W Fm mobile, 3.6m RG-58C/U to vertical.

  HF 100W Tx on 7MHz, 30m RG-58C/U to a dipole.

This calculator is designed to model the common configuration where a transmitter which is designed for a particular load impedance, is connected to a an antenna of that impedance, over transmission line of the same characteristic impedance. The calculator allows specification of the transmission line loss 'upstream' and 'downstream' from the measurement point. It is intended to provide a simple analysis of the system at the transmitter and at the antenna where a directional wattmeter is used to take measurements in the system at some convenient intermediate point. It assumes that the characteristic impedance of the transmission line is approximately real (ie a Distortionless Line), and that loss is low, and that loss per unit length is approximately uniform. For a more accurate result that does not depend on those assumptions, see RF Transmission Line Loss Calculator

Not all calculated results are applicable to all scenarios, user's need to understand the underlying principles to apply the results validly.

VSWR calculator help

RF Transmission Line Loss Calculator

RF Two Wire Transmission Line Loss Calculator

VSWR nomographs (PDF - you need Acrobat Reader)

Other tools.

V1.02. Use at your own risk, not warranted for any purpose. Do not depend on any results without independent verification. n -->


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