Topband: K9AY Loop Questions

Fri Jan 7 10:27:16 EST 2022

Hi Don

That's a very interesting question. The K9AY is ground dependent.  The reason is simple, the Loaded loop of flag has a resistor in one side and the transformer on the other side. If you want to make it reversible you need two relays, one on each end of the loop.

What K9AY did was genius, he created a transmission line between the horizontal wire and the ground. Keeping the horizontal wire close to the ground it does work as a transmission line and you can move the resistor and transformer close at the center of the wire. With the resistor and the transformer closed to the center you can use just one relay to reverse direction. The switching for 4 direction became easy to implement.

The horizontal wire must be close to the ground, is you raise the ends of the K9AY the impedance of the transmission line also raise and deteriorate the SWR on the loop, deteriorating the pattern as well.

Same on the SAL the ground is part of the antenna. Very different of the Flag and WF that is ground independent. You can install a flag or WF at 50 FT high and pattern will be the same , not the case of the SAL or K9AY. Not because the loop, but because the transmission line that allows you to move the resistor and the transformer close to the center of the antenna.

The SAL is the same, the two transformers 1:X loaded the wire as a resistor and a transformer, there is no magic about that, electrically it is a resistor load and a transformer, changing the name of the device does not change how it works. You cannot install the SAL far from the ground, it does not work, the same way the K9AY does not work far from the ground.

73's
JC
N4IS

-----Original Message-----
From: Topband <topband-bounces+n4is=comcast.net at contesting.com> On Behalf Of Don Kirk
Sent: Friday, January 7, 2022 12:15 AM
To: Jose_Carlos <N4IS at comcast.net>
Cc: W0MU Mike Fatchett <w0mu at w0mu.com>; topband <topband at contesting.com>
Subject: Re: Topband: K9AY Loop Questions

Hi Jose,

To keep things simple, I say the K9AY is not like a pennant or flag since it has been demonstrated by many people to be more ground dependent (sometimes needing added ground radials).  Under certain conditions the K9AY should be identical to a Flag or Pennant but since ground radials have been shown to drastically impact the K9AY performance depending on the ground conditions this sure does not sound like this is always the case.

I won't debate the SAL (Shared Apex Loop), other than to say from a construction standpoint it's definitely not the same as the K9AY or other EWE type antenna (Flag, Pennants, etc.), and modeling the SAL definitely yields a different pattern than a single pennant or flag when used in the "in line direction" but as you said modeling does not always reflect reality (your example was EZNEC not doing a good job with loops close to ground).  I have never used an SAL and therefore my statements are only based on what modeling yields, but to say the SAL is the same as a K9AY is hard to believe regardless if it performs better or worse than the K9AY, just based on the design.

P.S. I believe there is a newer version of the SAL in which the two halves of the SAL share the same center vertical conductor, but again I'm not making any claims about the design.  Also note I'm using 4NEC2 for my modeling, not that it necessarily impacts my above statements.

73,
Don (wd8dsb)

On Thu, Jan 6, 2022 at 10:27 PM Jose_Carlos <N4IS at comcast.net> wrote:

> Don
>
> I’m afraid your information is not accurate, SAL is the same as a 
> K9AY, the two wires close to each other can be removed because they 
> cancel each other. The remain wires works like two vertical in phase, 
> as the same in any flag, loaded loop or pennant. The cardioid pattern is the same.
>
> The is no implementation of two SAL in phase because it does not work, 
> the phasing system is too complex to phase two SAL.
>
> If you know the people that actually tested the antenna, you know that 
> the claimed RDF was never achieved.
>
> The RDF of the K9AY is the same of the SAL, the EZENEC does a horrible 
> job with loops close to the ground.
>
> Saying that, both antennas are excellent receiver antennas if you 
> don’t have anything else.
>
> 73’s
> JC
> N4IS
>
> Sent from Mail for Windows
>
> From: Don Kirk
> Sent: Thursday, January 6, 2022 7:19 PM
> To: W0MU Mike Fatchett
> Cc: topband
> Subject: Re: Topband: K9AY Loop Questions
>
> Hi Mike and gang,
>
> It has been a long time since I looked at the SAL in which I modeled 
> it with the help of the designer of the SAL (KB7GF).  The SAL is 
> actually different than the K9AY and other EWE types of RX antennas 
> which have a typical RDF value of around 7.8 because the SAL (Shared 
> Apex Loop) antenna actively uses two of its loops which are "in line" 
> with each other for what you might call the primary direction 
> (direction in line with the loops), and these two phased loops can 
> provide an RDF value of around 9.2 depending on the coupler locations.  
> For the off axis directions (45 degrees to the
> loops) I believe all 4 loops of the SAL are active (phased together) 
> and they provide a pattern more like what you would expect from the 
> K9AY or other EWEs with an RDF of approximately 7.8.  Therefore in the 
> 4 primary directions of the SAL the SAL definitely has a better RDF 
> than the K9AY or other types of EWE receiving antennas.
>
> When used "in line" the RDF of the SAL is around 9.2 as mentioned 
> above which is similar to what you would obtain using two phased 
> verticals with
> 1/8 wavelength spacing.
>
> Just FYI,
> Don (wd8dsb)
>
> On Wed, Jan 5, 2022 at 9:43 PM W0MU Mike Fatchett <w0mu at w0mu.com> wrote:
>
> > The SAL is pretty much just an AY loop with a more functional 
> > controller?  I have had moderate success with a pennant at V31 as well.
> >
> > W0MU
> >
> > On 1/5/2022 7:23 PM, john at kk9a.com wrote:
> > > I tried an AY loop decades ago, without the Array Solutions 
> > > adjustable termination controller, and I do not remember it being 
> > > that useful for
> > RX.
> > > The antenna is ground dependant so perhaps it works better for 
> > > some
> than
> > > others. Even a short Beverage may be a better choice. From my P40A
> > station I
> > > used a Pennant with decent results. It was inexpensive to build 
> > > and not ground dependant however it only covered one direction. 
> > > The Array
> > Solutions
> > > Shared Apex Loop Array has great reviews and may be worth 
> > > considering,
> > Pete.
> > >
> > > John KK9A
> > >
> > >
> > >
> > > Pete Smith N4ZR wrote:
> > >
> > > I recently installed a K9AY loop (with the Array Solutions 
> > > controller), and have a couple of questions.  Installation is 
> > > pretty standard, with
> a
> > > fiberglass pole at the center, ground rod at its base, and on the
> ground
> > > radials under each direction of the loop.
> > >
> > > The antenna is directional, as demonstrated by tuning in broadcast 
> > > stations at the high end of the AM band and separating stations on 
> > > the same frequency so that I can hear one or the other.  
> > > Atmospheric noise is 1-2 S units more on my inverted L than on the 
> > > K9AY antenna, but signal strengths of stations in the favored 
> > > direction of the loop seem about the same or a bit lower than the 
> > > inverted L.  The Termination adjustment is working, to judge by 
> > > the switching transients, but seems to make little or no difference.
> > >
> > > How do these results compare with others' experience?  I didn't 
> > > expect
> a
> > > "magic bullet", but the K9AY loop seems a little bit underwhelming.
> > >
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