Pete Smith wrote:
>
> At the risk of fanning the flames again, I think the original question was
> whether a change in line length could cause the apparent resonant frequency
> of an antenna to change. My 20M antenna has a feedpoint impedance of 35-j14
> at 14 mhz. If I mathematically attach a half-wavelength of RG-8 (using
> TLA.EXE), the impedance at the input end of the cable becomes 36-j 13.3,
> and the result, as you'd expect, is slightly lower SWR due to line loss.
> however, if the line is pruned to 1/4 wave, the resulting input-end
> impedance is 61.75+j23, and it appears that the antenna has magically moved
> from being short at 14 MHz to being long. The SWR hasn't changed,
> fundamentally, but the mix of reactance and resistance confronted by the
> AMP sure has, unless I misunderstand what the program is telling me.
>
> 73, Pete Smith N4ZR
> n4zr@contesting.com
>
> Sometimes a tower is just a tower
-----------------------
Hi Pete,
One thing most people on this reflector have forgotten or never really
understood:
SWR has NOTHING to do with resonance.
73, Bob, W5AH
--
FAQ on WWW: http://www.contesting.com/ampsfaq.html
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|