On Fri, 7 Jan 2005, J. Allen wrote:
tuner loss, the antenna impedance with the resistance of wire and loss
resistance, the antenna connection impedance estimates at 7.6 Ohms.
7.6 Ohm of coil resistence is reasonable. But it can be decreased if
increase a diameter of a coil. Very aproximative coil Q-factor is about
coil diameter in milimeters if step of wireing is optimal (step is twice
of wire diameter). This is for solid wire, not for litz. More exactly
Q-factor can be estimated also.
But usialy coil loss is not the main loss if Q-factor is large! Main loss
is a ground and enviroment loss! If conterpoise is elevated then ground
loss can be estimated by NEC-2. If it is burred then one need NEC-4. Or
one can use very aproximative formulas derived by me (look to archive of
this list).
Unfortunely all of this is true only if an antenna is out of trees,
buildings e.t.c. Othervice this enviroment yelds losses wich are much
grater then ground loss itself :-( I do not know how to estimate
enviroment losses theoreticaly :-( May be by elnec modeling of trees?
But it is a hard work!
It is not simple to estimate real LF antenna effectivity theoreticaly!
73 de RA9MB/Alex
http://www.qsl.net/ra9mb
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