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Old January 20th 04, 05:30 PM
Dave Shrader
 
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Cecil Moore wrote:

Craig Buck wrote:

I was talking about radiation efficiency taking into account the ground
losses. The ARRL Antenna Book equation is Efficiency = Radiation
Resistance
divided by the sum of Radiation Resistance + Ground loss + Coil loss.
Plug
in a 6 ohm ground loss and whatever you want to assume for the coil loss.
The higher the radiation resistance the higher the efficiency. No?



For an 8 ft center-loaded whip on 75m, the ARRL Antenna Book gives 0.8 ohms
as the radiation resistance and 22 ohms as the feedpoint impedance. That's
an efficiency of about 3.6%, about 4 watts radiated for 100 watts input.


Keeping Ground Loss and Coil Loss constant and increasing the radiation
resistance from 0.8 ohms to 1.6 ohms changes the efficiency to 7%. Hmmm
.... the higher the radiation resistance the higher the efficiency!!