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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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