Mike ~
I don't know how well the Flag Loop hears compared to a magnetic loop.
But, both are usually used with preamps and attenuators - so that you can
adjust the noise levels down to where the S-meter readings are most
sensitive.
WD8DSB (Don) has posted some pretty interesting videos on YouTube
showing how he uses his loops (with preamplifiers) for 160 meter DX'ing.
~ Alan K0AV
On Mon, Apr 12, 2021 at 11:37 AM Michael Aust <wb6dji_dx@icloud.com> wrote:
> Alan
> Does the Flag loop antenna hear noise
> ( Noise Sense Antenna ) better than say a
> Small 2 foot Magnetic Loop That resonates at 40meters ?
>
> Trying to use a loop than say a Magnetic Loop
> or a Vertical Mobile CA-HV 40meter coil type HF Whip with a DXE NCC-1 that
> acts as a noise Cancellation system with Amplitude and Phase
> adjustments
>
> Any comments appreciated
>
> Mike
> WB6DJI
>
>
>
> Sent from my iPhone
>
> > On Apr 12, 2021, at 8:57 AM, Alan Higbie <alan.higbie@gmail.com> wrote:
> >
> > In the past few days I've started using a Flag Loop antenna (designed by
> > WD8DSB).
> >
> > I supplement it by also using a National RF HF-DF bidirectional loop.
> >
> > The patterns on both have been confirmed by using a known signal source
> (RF
> > signal generator).
> >
> > Having a unidirectional antenna is very helpful. The null of the
> > cartioid pattern is quite pronounced.
> >
> > Example: for years now, I have had a noise source which seemed to be
> coming
> > from 40 deg. at times - and other times coming from 220 deg. I believe
> > that the results had been confounded by re-radiation along the power
> lines. Now
> > I have now definitely determined that it is from 220 deg. (i.e. a giant
> > step closer to location and resolution).
> >
> > An ** interesting feature ** of the Flag Loop is that it is broadbanded -
> > maintaining its directional properties over a big chunk of spectrum.
> > Unlike a tuned loop (or tuned yagi), a broadband antenna allows you to
> view
> > a huge piece of spectrum at once. And with an SDR this is quite easy -
> and
> > very interesting.
> >
> > Dave, NK7Z, has a blog where he describes using an SDR to make site RFI
> > survey. He was using a fixed broadband antenna.
> >
> > Look at Dave's work on this subject:
> > https://www.nk7z.net/rfi-site-survey-part-ii-interpretation/
> >
> > Having a broadband and unidirectional ROTATABLE antenna allows us to
> > quickly and more definitively see associations among the various sources.
> > And, simultaneously begin to find the RFI source.
> >
> > Yesterday I set my SDR to receive a section of spectrum from 3.0 to 11.0
> > MHz. Then I rotated the Flag Loop - - and the results were very
> > interesting: I could see some very strong and wide signals. These
> > appeared across the spectrum and which rose-and-fell together (meaning
> they
> > are from the same device). I had not realized that junk was there.
> >
> > Still don't know if these wide signals are ACTUALLY AFFECTING MY
> RECEIVER'S
> > NOISE FLOOR on any band. To be determined. Interesting nonetheless.
> >
> > *Why this matters*: a broadband / unidirectional antenna with SDR now
> > allows a view of what kind of RFI is really out there.
> >
> > 73, Alan K0AV
> > _______________________________________________
> > RFI mailing list
> > RFI@contesting.com
> > http://lists.contesting.com/mailman/listinfo/rfi
>
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
|