Date: Fri, 11 Jun 2010 12:07:23 -0800
From: Roger Brown <rogerbrown@gci.net>
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Subject: RE: LF: LF/VLF
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What kind of input power to the loop and vertical?

Roger KL7Q

-----Original Message-----
From: owner-rsgb_lf_group@blacksheep.org
[mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Mike-WE0H
Sent: Friday, June 11, 2010 10:59 AM
To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: LF/VLF

I did testing several years ago with a 200' TX loop and a 45' vertical 
with a 72' flattop. The band was 1750 meters. The loop and the vertical 
were mounted in the woods with 70' plus oak trees. What was found was at 
outside air temperatures of 32F and above, the vertical's signal hardly 
radiated groundwave or skywave. The signal from the vertical was barely 
audible at 75 miles and not visible in ARGO at 1000 miles. The TX loop 
signal was S-9 at 75 miles and showing real well in ARGO at 1000 miles. 
The groundwave receive station was at 75 miles from the TX site. The 
skywave station was at roughly 1000 miles from the TX site. As the 
temperature went down from 32F, the vertical's radiated signal increased 
until the temperature was roughly 10F where the vertical's signal 
matched the TX loops signal on both the 75 mile & the 1000 mile receive 
sites.

The TX loop was a Bill Ashlock loop design, series resonated with low 
loss caps and transformer coupled with a -43 material ferrite core. The 
transformer turns ratio was set to match a 50 ohm amplifier output 
impedance. This TX loop was in a vertical plane laying in the tree tops 
and running 6' off the ground on the bottom side.

Similar testing proved a TX loop was not necessary on the 600 meter band 
as trees do not significantly affect a 600m signal. Other US Amateur's 
have tested TX loops and verticals around trees on the 2200 meter band 
and found the TX loop was necessary on that band when there was a lot of 
trees nearby.

Mike
WE0H
WD2XSH/16
WD2XGI