Topband: K3NA Loop Array

[Rick Karlquist]

The lumped element delays shown on my web site are
virtually identical to coax delay lines when used within
the recommended bandwidth.  They use additional elements
to get flat delay.  You might have been thinking of a
network with the minimum number of elements to get a
given delay at a given frequency.  Those designs do NOT
result in flat delay.  I have verified this by
SPICE simulations.  Whether to used lumped or transmission
line delays is purely an implemenation preference; there
is no performance issue.  I built an 8 element vertical
array that used these delay networks and it had a good pattern
over a 4:1 frequency range.

Rick N6RK


Eric Scace K3NA wrote:
> I thought about lumped components for the delays.  I did not have time
> to evaluate a lumped-component system for maintaining the desired
> phasing over the entire band.  Did you look into this aspect, Rick?
>
> -- Eric
>
> on 2010 Jun 20 22:12 Richard (Rick) Karlquist said the following:
>> 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
>>>
>>>
>>> _______________________________________________
>>> UR RST IS ... ... ..9 QSB QSB - hw? BK
>>>
>>>
>>>
>> _______________________________________________
>> UR RST IS ... ... ..9 QSB QSB - hw? BK
>>
>>
>
>