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Old November 13th 03, 12:59 PM
Richard Harrison
 
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Yuri, K3BU wrote:
"My point is that I argued that current is different, not how precisely
I can calculate or offer calculted proof."

The 19th edition of the ARRL Antenna Book included a CD-ROM containing a
program to optimize whip loading. The book also has a section on loading
coil design.

Network analysis may be inapplicable, but the simple argument that the
current is likely different at the two ends of an antenna loading coil
is elegantly made by Fig 6 on page 16-4 of the 19th edition of the ARRL
Antenna Book. It shows a simple whip over a ground plane as an
equivalent circuit of distributed inductance and capacitance. It`s
obvious that capacitance near the feedpoint bleeds current to ground
which is thus unavailable at inductance further from the feedpoint. The
antenna is, unlike a transmission line, unbalanced. Some energy escapes
the confines of the antenna, and isn`t all available from temporary
storage to travel on its path along the antenna away from the feedpoint.
Decline of current in the loading coil is plotted in the figure.

Yuri`s point is proved. Look at Fig 6. The picture is worth a thousand
words.

Best regards, Richard Harrison, KB5WZI

 
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