Topband: Twist a Flag into a Bowtie?

[Nick Hall-Patch]

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 at ieee.org]
>Sent: Monday, December 12, 2016 10:59 PM
>To: JC <n4is at comcast.net>
>Cc: 'topband' <topband at 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 at contesting.com] On Behalf Of Don
> >Kirk
> >Sent: Sunday, December 11, 2016 10:13 AM
> >To: D Michael <damichael at verizon.net>
> >Cc: topband <topband at 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 at 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
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>Nick Hall-Patch
>Victoria, BC
>Canada

Nick Hall-Patch
Victoria, BC
Canada