Thread: Dish reflector
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Old April 24th 09, 05:21 AM posted to rec.radio.amateur.antenna
Art Unwin Art Unwin is offline
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First recorded activity by RadioBanter: Mar 2008
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Default Loading coils: was Dish reflector

On Apr 23, 8:04*pm, Cecil Moore wrote:
Tom Donaly wrote:
Nothing is perfect, but which is better, EZNEC or the Cecil-Corum method
of modeling antennas?


EZNEC and the Cecil-Corum method are in agreement.

Correct but the solution is in error as equilibrium demands that the
radiator is in equilibrium ie equal to a period or multiples there of.
Both of the above determined that resonance alone without reference
to the period was a reflection of equilibrium.
This may account for Krauss's error in determiming gain via Maxwells
law by determining a half wave was in equilibrium and thus determined
gain was approx
3db more than that was actually attainable. Later measurements mad by
others show that Kraus over estimated the gain by 100 % the equivalent
of 3db or the doubling of gain or energy expenditure.This error is
actually a reflection of pitch of windings which is a fraction of the
possible generated electric field for maximum efficiency.

Lesson
One must account for all actual vectors used within a boundary for
equilibrium
where the addition of all vectors finish at the starting point of the
period. The idea that a coil does not radiate is fallacious since the
charge is still accelerating but to a lesser extent than when current
moves along a straight wire. The total velocity factor is the average
velocity of that of a slow wave plus the velocity without the addition
of lumped loads ie straight radiator addition.This being equal to the
total length of wire
required with tha absence of lumped loading ie straight.
Regards
Art




--
73, Cecil, IEEE, OOTC, *http://www.w5dxp.com