From: andrew.ikin@xxxxxxxxxxxxx
To: irca@xxxxxxxxxxxxxxxx
Date: Mon, 20 Apr 2015 09:34:20 +0100
Subject: Re: [IRCA] Station #500! (Big Loop antennas)
Hello Chuck,
In the early days of the K9AY antenna someone ( I think it was a Swedish
Ham ) mentioned in the Yahoo K9AY groups that the E and H Fields were 90
degrees. No one offered a satisfactory explanation as to how this phase
difference would affect the pattern.
This is what I believe as to how the K9AY works.
The antenna is basically two aerials; a loop ( H Field ) and a Vertical
( E
Field ) due to the loops antenna return path being the ground
The induced current/EMF of the E/H Fields is 90 degrees out of phase or
put
it another way, the phase difference is +/- 45 degrees for example +45 for
the H field and -45 for the E field.
Each aerial shares the same termination resistance and is in series with
the
induced current/EMF and hence this modifies the resultant phase angle to
be
equal to Tan x loop reactance divided by the termination resistance.
Hence,
the resultant phase difference will be diminished.
Therefore, if the loops reactance is equal or less than the termination
resistance, the phase difference will be near to zero for signals off one
end of the loop and maximum off the other end. This due to the loops end
to
end phase difference being 0 and 180 degrees. Additionally the termination
resistance will amplitude balance the phase shifted induced current/EMF.
Hence, the cardioid pattern.
73
Andrew
-----Original Message-----
From: Chuck Hutton
Sent: Sunday, April 19, 2015 11:44 PM
To: irca@xxxxxxxxxxxxxxxx
Subject: Re: [IRCA] Station #500! (Big Loop antennas)
Hi Andy -
In my mind there are both E and H contributions to the total pattern.
But.....
Using AutoEZ and EZNEC, the H field signal is 12 dB below the E field at 1
MHz over average ground for the K9AY version of the K9AY antenna (30 feet
base and 25 feet high). Furthermore, the H field pattern is at right
angles
to the E field pattern. The H field therefore contributes nothing in the
forward direction.
> From: andrew.ikin@xxxxxxxxxxxxx
> To: irca@xxxxxxxxxxxxxxxx
> Date: Sun, 19 Apr 2015 21:45:58 +0100
> Subject: Re: [IRCA] Station #500! (Big Loop antennas)
>
> Hello Chuck,
>
> W8JI's words as to the operation of terminated loops is disputed by
> K9AY.
> Gary Breed K9AY is quite correct when he states the antenna relies on
> the
> both interaction of the E and H Fields. The H field response of any loop
> is
> proportional to the antenna area.
>
> The termination resistance performs two functions; to balance the
> resultant
> EMFs induced in the antenna and reduce the phase difference of these
> EMFs.
> Hence, the antenna gain is dependant on the loop area. BS Collins, who
> designed a Terminated loop array in the 70s and R Keen in the 1927 ed.
> of
> Wireless Direction Finding when describing a French design of the
> Terminated
> loop similar to the K9AY, both describe the antenna operation in a
> similar
> manner as Gary Breed.
>
> As a matter of interest one can double the loop area of the K9AY by
> using
> a
> two turn loop to increase the gain by approx. 5dB.
>
> 73
>
> Andrew Ikin
>
> -----Original Message-----
> From: Chuck Hutton
> Sent: Sunday, April 19, 2015 8:26 PM
> To: irca@xxxxxxxxxxxxxxxx
> Subject: Re: [IRCA] Station #500! (Big Loop antennas)
>
> For those interested, http://w8ji.com/k9ay_flag_pennant_ewe.htm has a
> paragraph describing the fact that the pickup for K9AY and other
> "terminated loops" depends solely on the "vertical" aspect of the
> slanted
> wires and no pickup is contributed by the horizontal section on the
> bottom.
> Area of the antenna (as referenced in the article below) is therefore
> meaningless.
> Chuck
>
> From: charlesh3@xxxxxxx
> To: irca@xxxxxxxxxxxxxxxx
> Subject: RE: [IRCA] Station #500! (Big Loop antennas)
> Date: Sat, 18 Apr 2015 20:11:26 +0000
>
>
>
>
> Guy -
> The John Bryant article is only about KAZ antennas and doesn't touch the
> DKAZ version.I have some issues with the article - using a "surface
> area"
> concept to compare antennas whose gain is largely dependent only on the
> height of the vertical sections is not right.
> Chuck
>
> > From: dx@xxxxxxxxxxxxx
> > Date: Sat, 18 Apr 2015 13:03:33 -0700
> > To: irca@xxxxxxxxxxxxxxxx
> > Subject: Re: [IRCA] Station #500! (Big Loop antennas)
> >
> > Hi Nick,
> >
> > John's article on large DKAZ antennas is the one that came to mind for
> > me
> > in this discussion of Super Loops. Although I believe a Super Loop is
> > rectangular, the big DKAZ may be of interest to Brian:
> >
> > http://www.dxing.info/equipment/kaz_bryant.dx
> >
> > John compared 112 Ft. X 28 Ft.and 40 Ft. X 10 Ft. DKAZ antennas for
> > this
> > article.
> >
> > 73,
> >
> > Guy Atkins
> > Puyallup, WA
> >
> >
> >
> >
> > > ---------- Forwarded message ----------
> > > From: Nick Hall-Patch <nhp@xxxxxxxx>
> > > To: Mailing list for the International Radio Club of America <
> > > irca@xxxxxxxxxxxxxxxx>
> > > Cc:
> > > Date: Sat, 18 Apr 2015 15:46:32 +0000
> > > Subject: Re: [IRCA] Station #500!
> > > Too big? Never say that.
> > >
> > > John Bryant ran some supersized Ewe antennas, for example 70 feet
> > > high
> > > by
> > > 100 feet horizontal at Orcas Island, but it suffered from grounding
> > > difficulties insofar as nulling was concerned compared with a
> > > Wellbrook
> > > array. I can't find any reference that he ever tried it as a
> > > Superloop..
> > >
> > > When he ran one closer in size to what you're doing in Oklahoma (27'
> > > high
> > > by 100' horizontal) over a good ground, he was suitably impressed,
> > > so
> > > I
> > > suspect the loop version will do you fine.
> > >
> > > This is based on e-mails exchanged. I can't find any formal
> > > articles,
> > > at
> > > least with a brief search. Seems odd, as John was a great
> > > documenter..
> > > Perhaps someone else can point us in the direction of a formal
> > > article..
> > >
> > > At any rate, I'd say that you should run with the big 'un. It
> > > might
> > > be
> > > good to run a smaller one too if you can, as my own experience with
> > > a
> > > larger one was that the nulls weren't as good as a smaller one, but
> > > that
> > > was queered by being on a city lot, and one end of the Superloop
> > > being
> > > very
> > > close to the house and its electrical wiring.
> > >
> > > best wishes,
> > >
> > > Nick
> > >
> > >
> > _______________________________________________
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> >
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> >
> > To Post a message: irca@xxxxxxxxxxxxxxxx
> >
>
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