NB., I had excellent results in the past with a half-size K9AY loop, only
about 12 ft high, vs the normal 25 ft or so as seen depicted on websites and in
the literature. At this size, its also 'good', that is, it is still directive,
as high as the 40 m band. I was using this half-size K9AY on the 630m band to
actually null a strong transmitting station one county south, as groundwave
from this station was quite potent!
One thing one will need is a 1:1 isolation transformer on the coax in the
shack, otherwise noise DOES make its way back down the coax to the 1/2 size
K9AY loop. Also, I only constructed 1/2 of this 'loop' and didn't really need
any relays, as, I had it positioned or fixed in only one direction. As it was
physically rotatable (though not on a rotator), I checked its performance
against a local AM radio station for F/B ratio and was satisfied it would yield
at least 20 dB or so F/B.
PS I needed no preamp between this antenna and a modern ham radio like an
IC-706 Mark II or a IC-756Pro3.
de AA5CT Jim
---------------------------------
On Wednesday, February 1, 2023, 5:04:12 PM GMT-6, Dave (NK7Z)
<dave@nk7z.net> wrote:
Cool... I am thinking of comparing it to a Mag loop. I am setting up a
RX only antenna for my K4, and suspect the cardioid pattern will do far
better than the pattern from a mag loop. Half the noise... :)
73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources
On 2/1/23 13:39, Don Kirk wrote:
> Hi Dave,
>
> I have not but I believe it should work (especially since a diamond
> works). You can look at other configurations that are known to work by
> reading the original article about Pennant and Flag receive antennas by
> Earl K6SE (SK) in the July 2000 issue of QST. I designed my portable DF
> antenna as a rectangle because I wanted the most gain possible that
> would still fit easily in my car.
>
> 73,
> Don (wd8dsb)
>
> On Wed, Feb 1, 2023 at 3:50 PM Dave (NK7Z) <dave@nk7z.net
> <mailto:dave@nk7z.net>> wrote:
>
> Don,
> Have you tried your design with a loop as opposed to the rectangle?
>
> 73, and thanks,
> Dave (NK7Z)
> https://www.nk7z.net <https://www.nk7z.net>
> ARRL Volunteer Examiner
> ARRL Technical Specialist, RFI
> ARRL Asst. Director, NW Division, Technical Resources
>
> On 2/1/23 12:09, Don Kirk wrote:
> > Hi Bob,
> >
> > Dave (W0LEV) provided you good insight. Normally I say just stay
> away from
> > wire wound resistors as we know they are definitely inductive,
> and carbon
> > resistors are just fine.
> >
> > Any value of termination resistor between 680 ohms and 820 ohms will
> > provide good results for use on my portable flag. There are just
> slight
> > trade offs between how a 680 and 820 resistor perform and you can
> see front
> > to back ratio versus elevation plots showing how the 680 ohm
> resistor and
> > 820 ohm resistor model. I actually have two identical portable
> flags, one
> > with a 680 ohm termination resistor and one with a 820 ohm
> termination
> > resistor and you would be hard pressed telling the difference
> unless I told
> > you what to look for in performance. You can see the plots on my
> portable
> > flag website at
> https://sites.google.com/site/portableflagantenna/
> <https://sites.google.com/site/portableflagantenna/>
> >
> > 73,
> > Don wd8dsb
> >
> > On Wed, Feb 1, 2023 at 2:26 PM Bob Kozlarek WA2SQQ
> <wa2sqq@gmail.com <mailto:wa2sqq@gmail.com>> wrote:
> >
> >> I started putting together one of your portable flag antennas.
> Regarding
> >> the resistor that is used by notice it’s called out as a
> non-inductive
> >> resistor. Is this something special or with a standard carbon
> comp or
> >> carbon film resistor work? If this is something that is super
> critical I’m
> >> thinking that I could put two or more larger values in parallel
> to arrive
> >> to desire value.--
> >>
> >>
> >>
> >> *Best 73 de WA2SQQElmwood Park, NJ"The only dumb questions are
> those we
> >> don't ask"*
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