[TowerTalk] modeling compare: 80M, 2EL vs 4SQ

[David Gilbert]

Well, the whole point of using elevated radials is to provide a return 
path for currents independent of whatever is below them (lossy ground, 
etc).  I have several times modeled a vertical with "tuned" radials at 
various points above ground (i.e., the vertical extends all the way to 
ground but the radials attach higher and the feedpoint is just above the 
radials) ... in every case, if the radials are "tuned" they choke off 
all current below them.  It's actually a relatively easy way to make a 
multiband vertical just by switching in/out the upper set of radials.  
I've only used EZNEC+ for this, but we're not talking the 
wires-near-ground limitation of NEC2 here.

So if the radials are indeed resonant, I don't see how whatever current 
might be induced into the ground screen ever gets back to the feedpoint 
to improve efficiency.  Maybe somebody smarter than me can educate both 
of us ...

73,
Dave   AB7E




On 3/17/2015 7:11 AM, Ed Sawyer wrote:
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> 3.  Elevated radials make sense versus using an extensive ground screen
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> over really poor ground, but again ... that only affects efficiency and
>
> not pattern, and doing both makes little sense.  The elevated radials
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> mostly shield the ground screen from providing any useful benefit unless
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> the ground screen is a lot larger than the area of the elevated radials.
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> Try listening to K3LR running EU on 80M and think again.  Ohio/Penn soil is
> not salt water and a 4 sq is a 4 sq.  So if the extensive ground screen over
> elevated radials is so useless - what is your explanation of the
> performance.
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>   
>
> Dave   AB7E
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>   
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