[AMPS] Voltage at antenna end. de K0FF

[measures]

>
>W3BP was asking about the voltage at the end of an antenna. I've been
>thinking about that too,
>Looking at a center fed 1/2 wave dipole: At 1500Watts, the 50 Ohm feedpoint
>sees 273V at 5.5 Amps if my math is correct. The end of the antenna is a
>very high impedance, and I'm just guessing at 3300 Ohms. 

Probably pretty close.  Wire diameter is a large factor.  

>It could be more.
>Based on end feeding a 1/2 wave we must match 3-5kOhms. The current is
>minimal but the voltage peaks, and it works out that 2-3KV would be present.
>Experience and gut feeling tell me that it must be or at least can be more
>than that. Anyone have the real figures? 

I measured the potential at the feedpoint of my 160m Hertz antenna.  (1/2 
wave end fed against gnd.)  With 100v-p input at 50-ohms, the antenna 
side of the L-network measured 1100v-p with my HP oscilloscope.  

>I doubt that we can take a direct
>measurement.
>
Doubt not.  

>Perhaps at the very end the current is zero and the voltage is
>infinite...not probable, but the range of possibility is large. Geo>K0FF
>
>
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>


-  Rich..., 805.386.3734, www.vcnet.com/measures.  
end


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