Hi, Group!
I have just derived formula for ground loss when conterpoise is burred.
Configuration is the same then conterpoise is elevated. But now
h is conterpoise depth. Also wire radius r appears in the formula.
Ground loss resistance for this case is:
R = 0.5*R0*ln( (H+h)^4/(8*H^2*r*h)
If H>>h then it can be simplifired:
R= 0.5*R0*ln( H^2/(8*r*h) )
As for elevated conterpoise it should be h>r here.
It seems interesting then if h=r (conterpoise is lie on ground surface)
formulas for elevated and burred conterpoise yeld approximately the same.
Some difference is not suprisely because this is the limit when formulas
works.
Also it seems very interesting and worth that antenna ground loss
resistance is NOT EQUAL to such a ground system resistance (on DC for
example). Groung system (horisontal burred wire) resistance is:
R = 0.5*R0*ln( l^2/(2*r*h) )
It is not very suprisely if note then E-field lines is essentialy
different for ground system and antenna with burred conterpoise.
If it is an antenna E-field lines starts on conterpoise and goes to
antenna. If it is a 'pure' ground system E-field lines starts on the
conterpoise and goes to infinity. Another field configuration yelds
another resistance.
It seems to me extremely worth then formulas show the conderpoise wich
lie on soil surface is the extremely bad case. To reduce losses
conterpoise should be elevated or burred to adequate depth. To elevate is
better...
73 de RA9MB/Alex
http://www.qsl.net/ra9mb
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