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Old April 5th 06, 01:33 PM posted to rec.radio.amateur.antenna
Richard Fry
 
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Default Current across the antenna loading coil - from scratch

Richard Clark wrote:
Any association between resonance, velocity of propagation, height,
width, etc. and something like our 118.60° tall antenna needs a heap
more explaining than resonance, velocity of propagation, height, width,
etc.

______________

Now responding specifically to your request for a heap of explaining, you
will find it in the George Brown paper I referenced earlier in this
sub-thread. As that IRE paper from 1945 may be difficult to access now, you
could refer to section 4-2 on the subject of cylindrical antennas in the
"Antenna Engineering Handbook," 2nd edition (pub. 1984), by Johnson and
Jasik -- from which this quote:

"In practive the antenna is always fed by a transmission
line. ... The effective terminal impedance of the line
(often referred to as the antenna impedance) then depends
not only on the length and diameter but also on the terminal
condition."

The text continues that for a MW monopole, the terminal condition consists
of the characteristics of the ground plane. This section includes the plots
of resistance and reactance for monopole radiators of various height to
width ratios from George Brown's 1945 IRE paper.

RF