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Message-ID: <F779EFC1E8B0455490000A3AD3E50E0D@gnat>
From: "Alan Melia" <alan.melia@btinternet.com>
To: <rsgb_lf_group@blacksheep.org>
References: <F607F91680294719BF83E8070F66B91D@AGB> <452F9ADDDA624E5EB9C8246BDDC6D264@gnat> <6FDC0CECCC3645EB922AF21E66965518@AGB> <AC509F93353848149D8E1E62C2D29305@gnat> <90E09B502D3D481992365586D42423DA@AGB> <5D772617FCC94283913EDABE7CB175FE@gnat> <5D44E645126C4841A77C08064C39E92C@AGB>
Date: Fri, 22 Jun 2012 01:22:10 +0100
MIME-Version: 1.0
Subject: Re: LF: Re: InV  L  Top  wire  config  - Best Option ??
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Hi Grahan .mmmmm 10 feet?? that could reduce your effective height to =
10feet makingi it 6dB (maybe not quite that bad) worse than the 40 foot =
pole on its own. The only plus point would be if that "radial" gives you =
a substantial reduction in ground loss.....which I doubt is the case.=20

Seriously you do need to measure it to get the best out of a difficult =
situation.......no amount of urban myth will give the right answer. =
Remember higher "aerial current" is no use if its going straight to =
ground (like a shunt cap across the feed point) and not traversing the =
radiation resistance. You want as much current as possible to flow =
though the radiation resistance (the vertical bit connected to the feed =
point) then you want a big cap (=3Dlow impedance) from the top of the =
loading coil  to earth for the "return current" (low loss resistance)  =
Not a very technical way of describing it :-))  even capacitance from =
the active pole to ground gives some loss....the inductive top load =
reduces that by reducing the voltage on that section.

Alan

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<DIV><FONT size=3D2 face=3DArial>Hi Grahan .mmmmm 10 feet?? that could =
reduce your=20
effective height to 10feet makingi it 6dB (maybe not quite that =
bad)&nbsp;worse=20
than the 40 foot pole on its own. The only plus point would be if that =
"radial"=20
gives you a substantial reduction in ground loss.....which I doubt is =
the case.=20
</FONT></DIV>
<DIV><FONT size=3D2 face=3DArial></FONT>&nbsp;</DIV>
<DIV><FONT size=3D2 face=3DArial>Seriously you do need to measure it to =
get the best=20
out of a difficult situation.......no amount of urban myth will give the =
right=20
answer. Remember higher "aerial current" is no use if its going straight =
to=20
ground (like a shunt cap across the feed point) and not traversing the =
radiation=20
resistance.&nbsp;You want as much current as possible to flow though the =

radiation resistance (the vertical bit connected to the feed point) then =
you=20
want a big cap (=3Dlow impedance) from the top of the loading coil =
&nbsp;to earth=20
for the "return current" (low loss resistance)&nbsp; Not a very =
technical way of=20
describing it :-))&nbsp; even capacitance from the active pole to ground =
gives=20
some loss....the inductive top load reduces that by reducing the voltage =
on that=20
section.</FONT></DIV>
<DIV><FONT size=3D2 face=3DArial></FONT>&nbsp;</DIV>
<DIV><FONT size=3D2 face=3DArial>Alan</FONT></DIV>
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