Hi, Bill.
On Thu, 14 Nov 2002, Ashlock,William wrote:
My present loop is constructed from .63" OD copper pipe. The figure of merit
for 50/50 loop antennas is the total AC resistance (Rac), including ground
losses, and this one measures under 0.4 ohms. An RG-8 loop of the same
dimensions will have a dry Rac of 0.60 ohms and is one that has more appeal
to the average Lowfer. Signal is down just 1.7db from the pipe loop.
The loop perimeter is 60 meters.
Wire resistance:
R1 [Ohm/m] = ( 0.084 / d[mm] )*sqrt(F[MHz]) =
( 0.084 / 16 )*sqrt(0.185) = 0.0023 Ohm/m
Rac (copper) = 60*0.0023 = 0.14 Ohm.
You get Rac = 0.4 Ohm . So enviroment loss resistance should be
0.4 - 0.14 =0.26 Ohm.
Someone wrong?
You get 0.6 Ohm if RG-8 used. Enviroment loss should be the same,
0.26 Ohm. So 0.60 - 0.26 = 0.34 Ohm is copper resistance of RG-8.
Then diameter should be 16*(0.14/0.34)= 6.6 mm. I am not familar with
RG-8. Is it diameter about 7 mm?
If TX power is about 1 kW it seems posible to get about 1 W ERP. Not
very bad...
73 de RA9MB/Alex
http://www.qsl.net/ra9mb
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