Correction to my previous comment.
I didn't realize that the mini-flag
impedance is close to 50 ohms resistive
at all frequencies of interest.
Therefore, the 50 NF of any amplifier
is also the NF that applies when connected
to the loop.
The 50 ohm source impedance is a due to a physical
...@gmail.com]
Sent: Wednesday, February 24, 2021 3:33 PM
To: john.kaufm...@verizon.net
Cc: TopBand List
Subject: Re: Topband: The WD8DSB mini-flag antenna
Hi John,
You started this mess (or maybe I did), and finally here is my response to a
few of the questions you had and thanks so much
>> 1. I am specifically talking about "small" loops.
The antenna in question is not a "loop" it is a terminated loop, the diagram
is a cardioid, it is very broadband 1-10, like 1 MHz to 10 MHz or 3 o 30 MHz
with the same irradiation diagram. The behavior is comparable a two dipoles in
On 2/24/2021 12:26 PM, n...@comcast.net wrote:
Hi Rich
" The problem here is that any loop antenna inherently has a noise
temperature of 300K, because it is lossy, and because it "sees"
the earth"
Would you elaborate on that? Small loop 1/10 of wave length works very
different from a loop
On 2/24/2021 12:54 PM, kol...@rcn.com wrote:
But I can recommend this: LAN-IQ SDR (Stand-alone SDR) (afedri-sdr.com)
Studying the fine print, the stand-alone unit needs either USB power or
7.5-10VDC. I've got a couple of 3 Ah Motorola-branded outboard cell
phone battery packs that look like
: Re: Topband: The WD8DSB mini-flag antenna
Hi Dave,
I hate to recommend anything and others have given you some good
recommendations, nevertheless I will make a few comments.
My workhorse radio for direction finding is the good old Realistic DX-440
(also sold as a Sangen ATS-803A) and you can
> Tim K3LR
>
>
> -Original Message-
> From: Topband [mailto:topband-bounces+k3lr=k3lr@contesting.com] On
> Behalf Of Don Kirk
> Sent: Wednesday, February 24, 2021 3:33 PM
> To: john.kaufm...@verizon.net
> Cc: TopBand List
> Subject: Re: Topband: The WD8DSB min
On 2/24/2021 12:33 PM, Don Kirk wrote:
As I have mentioned in a few other responses I suspect having the short
10 foot feedline helps to negate common mode noise
YES!
and direct signal
ingress into the feedline that often haunts us. I do have one
recommendation about pattern distortion as
To: john.kaufm...@verizon.net
Cc: TopBand List
Subject: Re: Topband: The WD8DSB mini-flag antenna
Hi John,
You started this mess (or maybe I did), and finally here is my response to
a few of the questions you had and thanks so much for waiting in line for
my response.
1) As I have mentioned
was
surprised how soon it arrived!
73, Kevin K3OX
- Original Message -
From: Don Kirk
To: David Raymond
Cc: topband
Sent: Wed, 24 Feb 2021 14:23:17 -0500 (EST)
Subject: Re: Topband: The WD8DSB mini-flag antenna
Hi Dave,
I hate to recommend anything and others have given you some good
Hi John,
You started this mess (or maybe I did), and finally here is my response to
a few of the questions you had and thanks so much for waiting in line for
my response.
1) As I have mentioned in a few other responses I suspect having the short
10 foot feedline helps to negate common mode
Original Message-
From: Topband On Behalf Of
Richard (Rick) Karlquist
Sent: Wednesday, February 24, 2021 12:50 PM
To: GEORGE WALLNER ; Don Kirk ;
topband@contesting.com
Subject: Re: Topband: The WD8DSB mini-flag antenna
On 2/24/2021 6:32 AM, GEORGE WALLNER wrote:
> Don,
> I put tha
because the width of the DXE mini-flag just
> > manages to fit inside the trunk of my mid-size sedan. A wider flag would
> > not fit.
> >
> > 73, John W1FV
> >
> > -Original Message-
> > From: Topband
> > [mailto:topband-bounces+john.kaufmann=
any pattern effects
>
> that
>
> > might be attributable to common mode degradation.
>
> Don, maybe you can
>
> > comment here as well on this aspect of the antenna.
>
> >
>
> > As I also mentioned in my earlier post, the dimensions of the DXE
>
> >
On 2/24/2021 6:32 AM, GEORGE WALLNER wrote:
Don,
I put that note out because friends were asking if with a
"ultra-low-noise" pre-amp they could use it for DX. Unfortunately,
that's not the case. (I have tried.)
George,
AA7JV/C6AGU
The problem here is that any loop antenna inherently has
Don's directional loop should significantly reduce my tracking time for most
common switching noise in the neighboring area. I currently use a National RF
loop + preamp with an SDR-IQ receiver strapped with Velcro to a notebook PC.
The SDR-IQ is powered from the PC's USB port.
It's very
On 2/23/2021 6:18 PM, David Raymond wrote:
Don. . .thank you for the very nice loop article in QST. And, thank
something portable to home in on it. Do you or anyone here any
suggestions for a reasonably good portable receiver with an external
antenna jack (might be hard to find?) that
uld
> not fit.
>
> 73, John W1FV
>
> -Original Message-
>From: Topband
> [mailto:topband-bounces+john.kaufmann=verizon....@contesting.com] On
Behalf
> Of Don Kirk
> Sent: Tuesday, February 23, 2021 5:22 PM
> To: wb6r...@mac.com
> Cc: Top Band List List
> Subject
Hi Rob,
Front to back ratio all depends on the arrival angle of the signal, and the
portable flag directional properties are just like full size flag
directional properties assuming you select the appropriate termination
resistor. On my portable flag website I show front to back ratio vs
Bi-directional loops lose their directivity for the most part, when
being applied to skywave signals. Is this mini-flag still
unidirectional on skywave? I would think not, but must ask.
73
Rob
K5UJ
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
> On 24 Feb 2021, at 02:18, David Raymond wrote:
>
> anyone here any suggestions for a reasonably good portable receiver with an
> external antenna jack (might be hard to find?) that will cover the 160m band
> . . .and maybe up to 30 MHz?
Hi Dave,
How about an SDR (e.g. RSP1A, Funcube
width of the DXE mini-flag just
> > manages to fit inside the trunk of my mid-size sedan. A wider flag would
> > not fit.
> >
> > 73, John W1FV
> >
> > -Original Message-
> >From: Topband
> > [mailto:topband-bounces+john.kaufmann=verizon@contestin
. A wider flag would
not fit.
73, John W1FV
-Original Message-
From: Topband
[mailto:topband-bounces+john.kaufmann=verizon@contesting.com] On Behalf
Of Don Kirk
Sent: Tuesday, February 23, 2021 5:22 PM
To: wb6r...@mac.com
Cc: Top Band List List
Subject: Re: Topband: The WD8DSB mini-fl
ld
not fit.
73, John W1FV
-Original Message-
From: Topband
[mailto:topband-bounces+john.kaufmann=verizon@contesting.com] On Behalf
Of Don Kirk
Sent: Tuesday, February 23, 2021 5:22 PM
To: wb6r...@mac.com
Cc: Top Band List List
Subject: Re: Topband: The WD8DSB mini-flag antenna
HI Stev
esting.com] On Behalf
Of Don Kirk
Sent: Tuesday, February 23, 2021 5:22 PM
To: wb6r...@mac.com
Cc: Top Band List List
Subject: Re: Topband: The WD8DSB mini-flag antenna
HI Steve,
Thanks for the nice implementation comment.
The portable flag front to back ratio is highly related to the eleva
HI Steve,
Thanks for the nice implementation comment.
The portable flag front to back ratio is highly related to the elevation
angle and frequency of operation (just like any terminated loop), and
therefore I did not want to overstate the front to back ratio in my
portable flag article. I
For finding 160 meter noise sources, I use a C-Crane or Sangean
pocket AM band radio tuned to 1710 kHz. It also has a very sharp
null due to the ferrite loop stick antenna built in. The QST
antenna does have the advantage of being unidirectional, but I
can often triangulate with the pocket
Yes very nice article and design by Don.
Flags/loops do not exhibit gain but rather directivity. The larger the loop the
greater the capture area and the less of a need for a preamp. I routinely use
my full size flag without any preamp external to the rig.
A correctly designed and built full
Some of you may have seen the article by WD8DSB in the latest issue of QST.
I believe WD8DSB is on this reflector. His article describes a mini-flag
antenna that can be used for direction-finding. The neat thing about this
antenna, besides its compact size, is that it is unidirectional and is
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