Hi Nick
I would say grounded both ends, don't need to be connected to the antenna
itself, right.
JC
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of Nick
Hall-Patch
Sent: Tuesday, December 13, 2016 11:42 AM
To: JC <n4is@comcast.net>
Cc: 'topband' <topband@contesting.com>
Subject: Re: Topband: Twist a Flag into a Bowtie?
So, is the ground wire just left "floating", JC? No electrical
connection to the antenna itself?
Thanks and 73,
Nick
VE7DXR
At 11:23 13-12-16, JC wrote:
>Hi Nick
>
>The wire will reduce loss on the transmission line given a better match
>and phase. In practice you can see change on the SWR and front back. If
>you have a good ground you probably won't see anything changing.
>
>Regards
>JC
>
>-----Original Message-----
>From: Nick Hall-Patch [mailto:nhp@ieee.org]
>Sent: Monday, December 12, 2016 10:59 PM
>To: JC <n4is@comcast.net>
>Cc: 'topband' <topband@contesting.com>
>Subject: Re: Topband: Twist a Flag into a Bowtie?
>
>What kind of improvement in performance is observed by providing a
>better ground, JC? And, where would a ground wire (counterpoise?) be
>connected with the DHDL antenna system?
>
>Thanks and 73,
>
>Nick
>VE7DXR
>
>
>
>At 15:38 11-12-16, JC wrote:
> >Hi Mike and Don
> >
> >The DHDL as well as few other antennas, has a hidden component. The
> >bottom wire parallel to the ground is a transmission line, actually,
> >any antenna parallel to the ground is a transmission line. A
> >beverage antenna a is good example.
> >
> >The ground is the second leg of the transition line, for a K9AY loop
> >it is the same, the bottom wire and the ground form a transmission
> >line. The transmission line allows the Resistor and the Transformer
> >to be moved to the center of the loop. The VE3DO loop is also exactly
> >the
>same.
> >
> >The same way, a DHDL antenna uses the ground to phase the two loops,
> >if you elevate the DHDL high far from the ground, the patter changes.
> >The DHDL is a ground dependent antenna, improving the ground with a
> >ground wire bellow the antenna can fix some ground problems.
> >
> >
> >My two cents.
> >
> >73's
> >JC
> >
> >N4IS
> >
> >-----Original Message-----
> >From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of
> >Don Kirk
> >Sent: Sunday, December 11, 2016 10:13 AM
> >To: D Michael <damichael@verizon.net>
> >Cc: topband <topband@contesting.com>
> >Subject: Re: Topband: Twist a Flag into a Bowtie?
> >
> >Hi Mike,
> >
> >Funny you should ask that.
> >
> >A few months ago (September) I was looking at building a smaller size
> >DHDL using 4Nec2, and there were a few things I saw that I thought
> >needed improvement (I saw things in the full size DHDL that I thought
> >needed improvement, it was not limited to the small size DHDL I was
> >trying to design). Then I started to play around with the location
> >of its termination resistor as well as routing of wires, and wound up
> >with what I called the Terminated Bowtie. I built one in my backyard
> >but my yard is pretty small and the antenna was too close to existing
> >objects (house and chain link
> >fence) and I did not realize the S/N improvement that I expected,
> >nevertheless based on modeling it looks like a winner (9.5 RDF and
> >front to back ratio versus elevation angle very robust).
> >
> >I have attached the preliminary document I put together a few months
> >ago for you and others to view (it might not be perfect, but should
> >convey my design / thoughts). I would love someone to build one of
> >these out in the open to see if the real life build provides results
> >similar to the 4Nec2 modelling I did.
> >
> >Note: Bringing the feedline away from the antenna properly needs to
> >be looked at to minimize distortion of the pattern. As I recall the
> >feedline should not drop down to the ground until it's at least 5
> >feet away from the antenna, and a greater distance would be best.
> >The feedline should also use choke with ground rod similar to what's
> >recommend for other RX antennas we use (beverages, flags, etc.) to
> >block common mode noise from making its way to the antenna feedpoint.
> >
> >Let me know what you think. It might not work, but sure looked good
> >on paper.
> >
> >73,
> >Don (wd8dsb)
> >
> >On Sun, Dec 11, 2016 at 9:41 AM, D Michael <damichael@verizon.net> wrote:
> >
> > >
> > >
> > > I have two flag rx ants and I was looking at the DHDL and DK6ED
> > > Double Loop System V2 and wondering if twisting my Flag rx ants
> > > into Bowties would improve the forward pattern and make them
> > > narrower with better front to back.
> > > I would just ""flip"" the termination resistor end to form a loose
> > > BOWTIE shape.
> > > I have no ant modeling software so I have no way to ponder this
change.
> > > Maybe someone could model doing this.
> > > TNX es 73, Mike W3TS
> > > _________________
> > > Topband Reflector Archives - http://www.contesting.com/_topband
> > >
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>
>Nick Hall-Patch
>Victoria, BC
>Canada
Nick Hall-Patch
Victoria, BC
Canada
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