[Lowfer] Small loop calculator

[Bill Ashlock]

Hi Laurence.....Long time!

 

Unfortunately 99% of my loop experimentation was in Andover, MA, at 185K and I can only conjecture what happens when a traditional LF loop is operated at 500K. One of my my 200ft diam Ashlock Loops up north uses 3/8s inch CU tubing and behaves at 500K fairly close to how it  behaves at 185K. Meaning that the measured Rac, results using ferrite step-down Xfmrs, resonating approaches, and radiation patterns are similar. The loss from resting on trees has yet to be measured.

 

Not sure what your soil conductivity will be like in Alaska but I have shown at 185K that soil conductivity has a marked effect on a loop's signal - both sky wave and surface wave. I have two I identical antennas set up to demonstraight this - one in Ellsworth and one in Andover running exactly the same current. Last winter the loop in Andover consistently showed up on the Grabulator (sky wave propagation) with over 6db of signal strength over the Ellsworth loop. Reports from approx 1000 mi, although far less regular, were similar. Also the falloff with distance in the 10 to 50mi surface wave range is much greater for the Ellsworth loop. Will be really interesting to run the same test at 500K and plan to do this next winter.

 

Wish I could offer more help. The house-building in Ellsworth which has turned into a 'supper green' design has all but consumed all my available time.

 

Bill 
 
> From: hellozerohellozero at hotmail.com
> To: lowfer at mailman.qth.net
> Date: Fri, 5 Jun 2009 22:38:50 -0800
> Subject: [Lowfer] Small loop calculator
> 
> 
> 
> 
> If been trying to calculate what sort of Voltages and impedances Im going to be faced with on my LF/MF loop in Alaska at 505-510kHz compared to 137khz and been fiddling with the values of
> 
> length diameter, capacitor values and voltages...
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> 
> 
> http://www.66pacific.com/calculators/small_tx_loop_calc.aspx
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> 
> 
> Im not sure given the real world of heights, ground permitivity, true conductor/skin whether it holds thru but plumbing in the figures for past oprations, in order of values it appears to give rationale figures. In all cases it tells me to keep the length less that 0,25Y...
> 
> 
> 
> Other good educational reading and the politicking of when a small becomes intermediate or large, and some good telling graphs on the links below.
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> http://personal.ee.surrey.ac.uk/Personal/D.Jefferies/loop.html and
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> http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=15200
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> 
> Anyone have any novel methods of feeding say a 470ft circumference loop at 505khz down to coax in the end welcomed....
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> 
> 
> Laurence WE2XPQ as of next week...
> 
> BP51 Wasilla AK
> 
> 
> 
> Presently OM89UA China.
> 
> 
> 
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