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-boun...@contesting.com] On Behalf Of Nick Hall-Patch Sent: Tuesday, December 13, 2016 11:42 AM To: JC <n...@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:n...@ieee.org] >Sent: Monday, December 12, 2016 10:59 PM >To: JC <n...@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-boun...@contesting.com] On Behalf Of > >Don Kirk > >Sent: Sunday, December 11, 2016 10:13 AM > >To: D Michael <damich...@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 <damich...@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 > > > > >_________________ > >Topband Reflector Archives - http://www.contesting.com/_topband > > > >_________________ > >Topband Reflector Archives - http://www.contesting.com/_topband > >Nick Hall-Patch >Victoria, BC >Canada Nick Hall-Patch Victoria, BC Canada _________________ Topband Reflector Archives - http://www.contesting.com/_topband _________________ Topband Reflector Archives - http://www.contesting.com/_topband