[Antennaware] Dual output K9AY

Andy Ikin andrew.ikin at btopenworld.com
Mon May 25 15:49:58 PDT 2009


Thank you for looking into the modelling feature.

The reason for trying to model the Dual output was to determine the phase 
relationship verses freq. required to increase the rear null by subtracting 
some of the front lobe from the rear. I did some work on this in May 2001, 
but ran into problems with the phasing. Misek uses this technique on his 
Steerable Wave antenna in his Beverage Handbook. However his Phasing system 
is not wide-band.

The test set-up was to use 2 x 9:1z xmfr at each ends of the loop at the 
junction of the ground wire. Both xmfr outputs connect to  Phasing box. One 
channel is a variable 0-165ns delayline (terminated 50R). The other channel 
has the amplitude control. The phasing box provides a constant 50 Ohm input 
for any phase or amplitude setting. Also the phase delay is constant for 
variations in Freq.

First I wired the K9AY xmfrs so that the Phasing box would combine in-phase 
plus the 0-165ns delayline. Result no increase in gain.

Next I re-wired K9AY xmfrs so that the Phasing box would combine anti-phase 
plus the 0-165ns delayline. The gain dropped by approx. 6dB, however, the 
rear null could be simply adjusted to upto -50dB with just tweaking the 
Phase and amplitude control. Across the MW band the average delay was 65ns, 
so most of the null adjustment was with the amplitude balance. The max null 
was far higher than using remote variable termination.  The results were 
much better than I had in 2001 with the improvement in the phasing system.

Btw, this technique doesn't work with RC phasers e.g. MFJ and Dxeng except 
over a narrow bandwidth i.e. the knob fiddling becomes tedious with changes 
with freq.

Getting back to the model, my thoughts are to simulate the Dual output K9AY 
is to model 2 K9AY close together and take the source from each antenna.



----- Original Message ----- 
From: "Pete Smith" <n4zr at contesting.com>
To: "Andy Ikin" <andrew.ikin at btopenworld.com>; <antennaware at contesting.com>
Sent: Monday, May 25, 2009 10:19 PM
Subject: Re: [Antennaware] Dual output K9AY

> 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 
>>>>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 
>>>>Andrew Ikin
>>>>Antennaware mailing list
>>>>Antennaware at contesting.com

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