Topband: K3NA Loop Array

[Richard (Rick) Karlquist]

I built a loop the same size as in the forum paper and the bandwidth
was something like 10% of what was shown.  I used critical coupling
(ie a conjugate match).  In order to cover the whole 160 meter band,
it would have been necessary to greatly over-couple to drastically
lower the loaded Q.  This is easy to do by simply reducing the
turns ratio.  This would result in a sensitivity reduction of 10
or 20 dB.  This might be OK in the usual noisy environment.   OTOH,
I'm not sure that many people need the whole 160 meter band.  My
loop is described in the Sept/Oct 2009 National Contest Journal.
It is not intended to use in an array.

In the forum article, I don't understand the impedance step
from 1 to 2 on page 49.  It appears that the resistor is more
like 20 ohms than 2 ohms.  In any event, considerable degeneration
is happening somehow.  The forum article criticizes W8JI's
swamping technique but seems to follow suit.

The combining network uses 100's of meters of phasing lines.
These are easily replaced by their lumped element equivalents:

http://www.n6rk.com/Lumped_LC_Delay_Networks.gif

Rick N6RK



Luis Mansutti IV3PRK wrote:
> Hi Topbanders,
> 
> I read the very fine presentation by Eric Scace, K3NA, at 2009 Dayton 
> Antenna Forum on a new Rx Loop Array.
> http://www.kkn.net/dayton2009/dayton-2009-antenna-forum.html
> 
> I like to test every kind of Rx antenna, but the matching of this array 
> seems (to me) not as simple as with verticals or flags.
> I don't understand the 4-stage network and the related K2TJ monte carlo 
> analysis.
> 
> Did anybody get inside this project, or tried to build it ?
> 
> Thanks in advance for any comment.
> 
> 73
> Luis IV3PRK
> 
> 
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