Pete,
If I leave the 390 ohm load in the model the Dual output model gain is okay.
In fact this is what I have done by using 2 matching transformers i.e. the
matching transformer is the load!!
I believe that Gary's explanation in his QST article of the loop pattern
being the result of both the E and H field is correct. Because the K9AY
appears to have a near field response to both fields, when compared to
active H-Field loop and a active E-Field dipole. I don't accept the short
vertical explanation.
73
Andrew
----- Original Message -----
From: "Pete Smith" <n4zr@contesting.com>
To: "Andy Ikin" <andrew.ikin@btopenworld.com>; <antennaware@contesting.com>
Sent: Tuesday, May 26, 2009 10:59 AM
Subject: Re: [Antennaware] Dual output K9AY
> Thanks for the quick reply, Andy. I am no theoretician, but I recall a
> discussion of the K9AY loop in which one well-qualified engineer asserted
> that it could/should be viewed as a close-spaced array of two short
> near-verticals, phased by the wire between them. If this is in fact the
> mode of operation, then feeding each "vertical" separately, while
> retaining the top connection between them, seems like a real muddle from
> the standpoint of phasing. Modeling two side-by-side loops also wouldn't
> really be faithful to the real-world antenna, would it?
>
> 73, Pete
>
> At 06:49 PM 5/25/2009, Andy Ikin wrote:
>>Pete,
>>
>>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.
>>
>>73
>>
>>Andrew
>>
>>
>>
>>
>>----- Original Message ----- From: "Pete Smith" <n4zr@contesting.com>
>>To: "Andy Ikin" <andrew.ikin@btopenworld.com>;
>><antennaware@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!!!!
>>>>
>>>>73
>>>>
>>>>Andrew (G8LUG not active )
>>>>
>>>>
>>>>
>>>>----- Original Message ----- From: "Pete Smith" <n4zr@contesting.com>
>>>>To: "Andy Ikin" <andrew.ikin@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??
>>>>>>
>>>>>>73
>>>>>>
>>>>>>Andrew Ikin
>>>>>>_______________________________________________
>>>>>>Antennaware mailing list
>>>>>>Antennaware@contesting.com
>>>>>>http://lists.contesting.com/mailman/listinfo/antennaware
>>>>
>>>>
>>>
>>
>
>
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