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Old October 23rd 14, 12:07 PM posted to rec.radio.amateur.antenna
John S John S is offline
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Default Do short antennas get hot?

On 10/22/2014 1:57 PM, Helmut Wabnig wrote:


Somebody wrote:

If 10 watts is delivered to a short antenna, where does it go if it is not
radiated just as well as 10 watts delivered to a long antenna?


Make it 100 Watts, make it 1000 Watts,

Transmit for 5 minutes, then switch off and measure temperature.

Is the short antenna hotter?


w.


Theoretically, yes. For #18ga Cu wi

Lambda Efficiency
0.5 0.9690
0.25 0.9402
0.1 0.8622
0.05 0.7571

Hence, about 24% of the power in the shortest antenna is lost due to
I^2*R. In addition, the shorter antenna has less surface area to rid
itself of the heat.

However, as a practical matter, it would be exceedingly difficult to get
much power into the antenna as its terminal impedance is 0.69-j5323.51 ohms.

John KD5YI