[Antennaware] Dual output K9AY

Pete Smith n4zr at contesting.com
Mon May 25 14:19:36 PDT 2009

Andrew, I am very suspicious.  Running this model in Multinec (NEC2) 
and 4NEC2, it appears to be very sensitive to the value of the 
assumed ground resistance.  At 200 ohms, it gives me a peak gain 
-18.4 versus average of -26.  At 100 ohms the figures are -15.4 and 
-23.2, and at 50 ohms -12.4 and -20.2.  At 5 ohms the values are -3.1 
vs -11.  The reference single-feed version gives -26 vs -34.

I ran the same dual feed arrangement with another model of the loop, 
as modified by W7EL.  He uses a pair of 50-foot radials perpendicular 
to the plane of the loop in lieu of a direct ground connection, 
Real-Sommerfeld ground and no series resistance to ground.  That 
model gives quite similar results, -9.8 dB vs -17.95.  The reference 
single-feed version gives -25.9 vs -33.94.

I can't explain the results, but I fortunately, it should be fairly 
easy to test. an 8 to 16 dB difference in signal strengths between 
the reference loop and the dual-feed design should really be 
obvious.  I'll be interested to see how your tests come out.

73, Pete N4ZR

At 04:57 AM 5/25/2009, you wrote:
>Pete, Guy, Gary and Terry;
>Please see attached files. The original K9AY model ( K9AY _ALT.EZ ) 
>is, I believe one from Terry but with the 200 Ohm res. in the ground 
>wire as per a model from Gary.
>The Dual opt K9AY.EZ is with the 390 Ohm load replace with a Source.
>Btw, I am going to test it this morning using a varible delayline 
>Phasing Unit . If the model is right then the correct phasing from 
>500kHz to 2MHz is a 54ns delayline!!!!
>Andrew (G8LUG not active )
>----- Original Message ----- From: "Pete Smith" <n4zr at contesting.com>
>To: "Andy Ikin" <andrew.ikin at btopenworld.com>
>Sent: Sunday, May 24, 2009 10:08 PM
>Subject: Re: [Antennaware] Dual output K9AY
>>Can you put the model file somewhere we can download it?  EZNEC or 
>>NEC-2 or?  This potentially looks very interesting, either with 
>>switchable phasing or maybe with a phaser in the shack, like the DX 
>>Engineering or MFJ units.
>>73, Pete N4ZR
>>At 04:53 PM 5/24/2009, you wrote:
>>>Hello guys,
>>>I have been trying to model a Dual Output K9AY I.e. taking another 
>>>output from where the termination is normally placed. Then combine 
>>>the two equal amplitude outputs with a small phased shift:
>>>10 deg. at 500kHz; 20 deg.at 1MHz; 30 deg. at 1.5MHz, 37 deg. at 1.85MHz.
>>>This provides the typical K9AY pattern. However, the gain 8dB 
>>>higher at 1.85MHz and 22dB higher at 0.5MHz compared to the K9AY.
>>>I have yet to verify the model. However, does the model change stack-up??
>>>Andrew Ikin
>>>Antennaware mailing list
>>>Antennaware at contesting.com

More information about the Antennaware mailing list