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Date: Mon, 20 May 2002 13:34:15 +0000 (GMT)
From: "Alexander S. Yurkov" <fitec@omskcity.com>
To: rsgb_lf_group@blacksheep.org
Subject: LF: more acurate formula for ground loss
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Hi, Group!

I have derived more acurate formula for ground loss then previous one.
This formula show previous formula is extremely aproximate.
Factor of number units was losssed...

New formula is derived for such a configuration. T or inverted L
antenna is assumed. Height of horisontal part of antenna is H.
It lenght is l. Conterpoise is up (!!!) from the ground on heght
of h. h can not be less then wire radius. Conterpose length is l also.
H<<l is assumed. s is ground conductivity, pi = 3.14159... Unfortunely it
is very complex to describe conterpoise length not equal to antenna
horisontal part length. It is posible but formulas is extremely long and
complex. May by I'll can simplificate it in future. 

For such a condition ground loss resistance R is:

R = R0 * ln( ((H+h)^2) / (4*H*h) )

where 

R0 = 1/(pi*s*l)

ln - natural logarithm.

It seems to me than this formula is acurate if there is no enviroment
losses. Unfortunely I can not describe enviroment loss yet.


For h<<H formula can be simpificated:

R = R0 * ln( H/(4h) )

In previous formula logarithm factor was lossed, sorry.

May be if conterpoise is up from the ground it is posible to decrease
ground loss compared to case when conterpoise lie on the ground or is
burred. I have analyse this by this formula. I found that there is optimal 
conterpoise heght  h if coil loss resistanse is taken in consideration.
Attention, coil loss resistance is worth for this analyse!

Unfortunely this can be done only if enviroment losses is neglet.


73 de RA9MB/Alex
http://www.qsl.net/ra9mb