Topband: EIRP Measurement

Richard Fry rfry at
Wed Feb 22 05:14:30 PST 2012

The maximum power radiated by a short monopole antenna system may be 
calculated using equations found in standard engineering texts.

The link below shows a system with a 50 ft monopole radiating 1 watt EIRP on 
630 kHz using the values shown for the r-f loss in the loading coil and r-f 
ground connection.

In this case the transmitter output power needed is over 100 watts.  Also 
note the high base voltage of the monopole, even at this low radiated power.

The inverse distance groundwave field strength at 1 km is about 7.2 mV/m.

Richard Fry 

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