This calculator will calculate the radiation resistance of a Marconi antenna which is short compared to the wavelength. Formulas are taken from this excellent page by ON7YD.

Enter antenna height in metres:

Enter antenna horizontal segment length in metres:

Enter frequency in MHz:

Enter antenna impedance (dominated by ground loss plus inductor loss) in ohms:

Enter transmitter power output in watts:

The wavelength in metres is:

The radiation resistance in ohms is:

The antenna efficiency is:

The approximate antenna capacitance in pF is:

The required inductance in uH is:

The antenna current in A is:

The antenna voltage in V is:

The total radiated power in watts is:

The EIRP in watts is:

Many thanks to Ben N1VF for pointing out a mistake in the calculation of hte radiation resistance! Rectifying this mistake results in slight increase of the calculated Ra with respect to the previous version.

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