Re: Topband: Bowtie Flags

[JC]

Sorry, the invention was in 1938 and the patent issued 1941

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of JC
Sent: Tuesday, December 13, 2016 6:28 PM
To: 'Don Kirk' ; 'Mark Connelly' 
Cc: 'topband' 
Subject: Re: Topband: Bowtie Flags

Hi Mark

Terminated loops are very old, the first patent belongs to Harold Beverage 

Harold Beverage invented wide band receiver antenna, loaded loop in 1941

https://docs.google.com/viewer?url=patentimages.storage.googleapis.com/pdfs/
US2247743.pdf

Most variations of this kind of antennas like this was used by military
during WWII. Some commercial versions started to come up on the 60's, Tom
W8JI worked the first JA using a similar RX antenna with multiple loops
phased end fire.

You see, the loaded loop is a Beverage antenna too.

73
N4IS


-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Don Kirk
Sent: Tuesday, December 13, 2016 2:08 PM
To: Mark Connelly 
Cc: topband 
Subject: Re: Topband: Bowtie Flags

Hi Mark,

I had no idea a terminated bowtie previously existed, but does not surprise
me.

Thanks for posting.
Don

On Tue, Dec 13, 2016 at 2:00 PM, Mark Connelly via Topband <
topband@contesting.com> wrote:

> As Nick undoubtedly knows, Bowtie antennas have been in use by medium 
> wave broadcast band DXers for some time now.
>
> One I tested here in 2010 is shown in this sketch:
> http://www.qsl.net/wa1ion/pictures1/bowtie_s_yarmouth.gif
>
> Some use a dual feedline scheme so the pattern can be reversed.  This 
> would be implemented by 16:1 transformers at each end if 50-75 ohm 
> coaxial cable is used or 9:1 transformers if using 90-150 ohm balanced 
> feed (CAT-5, speaker wire, two conductor zip / lamp cord, twisted pair
> etc.) as recommended by Dallas Lankford and others.  In the balanced 
> feedline case, a 1.8:1 or 2:1 transformer (e.g. #73 binocular core 
> with 4 turns : 3 turns or 7 turns : 5 turns) is used in-shack to get 
> to unbalanced coaxial en route to the receiver / transceiver, RPA-1 or
similar amp, or phasing unit.
>
> Dual feedline split flag is another variant:
> http://www.qsl.net/wa1ion/pictures1/dual_feed_split_flag.gif
>
> Dual feedline antennas have a 4-pole 2-throw switch at the shack end 
> so either end can be switched to the receiver path and the opposite 
> end to a
> 250 or 500 ohm pot that facilitates in-shack null termination adjustment.
>
> Some people go with a single orientation antenna and put a preamp such 
> as the Wellbrook FLG100LN ( http://www.wellbrook.uk.com/FLG100LN-1 ) 
> right at the forward side.  This tends to overwhelm any feedline 
> pick-up (common-mode or otherwise) although common-mode choking is 
> still advisable near the antenna when longer runs (over 60m / 200 ft.) 
> of feedline are involved.
>
> In the case of a single orientation set-up, you then get to figure out 
> what termination end scheme is best.  These basically boil down to the 
> following options:
> (1) Fixed resistor in the 680-1200 ohm range either modelled / 
> guessed-at or determined by use of a potentiometer if it can somehow 
> be adjusted midway up the side of the antenna while monitoring a 
> target
station to null.
> (2) "Vactrol" termination: a photoresistor adjusted by a DC voltage 
> applied on a control line from the shack: see page 9 of 
> http://www.durenberger.com/documents/PRESBT2016.pdf
> (3) Potentiometer adjusted by a motor drive: see 
> http://www.bamlog.com/ remotepotbox.htm
>
> My experience with the Bowtie I installed in 2010 was that it was 
> about
> 10-12 dB less sensitive than a Flag or Kaz Delta occupying the same 
> rectangular "box" of air space.
>
> Nulling off the back could be wider than that of a Flag but the 
> bandwidth at which the null stayed optimum at a particular terminating 
> resistance was not as wide as with the Flag (or its SuperLoop base-fed
variation:
> http://www.bamlog.com/superloop.htm ).
>
> Seeing that the MW broadcast band 530-1710 kHz has a greater max/min 
> frequency range ratio than the 1800-2000 kHz of 160m, issues that 
> might be problematic for broadcast DXers could matter a lot less on 160.
>
> Some of the perceived problems of low gain and null bandwidth could 
> easily have been cured by a combination of rigorous common-mode 
> choking as done on the Waller Flag ( 
> http://www.kkn.net/dayton2011/N4ISWallerFlag.pdf ) and high gain
at-antenna amplification.
>
> Mark Connelly, WA1ION
> South Yarmouth, MA
>
> <<
> Nick,?
>
> ?
> Although I did not measure it, the front to back, and front to side is 
> better, overall more quiet.
> ?
> It is receiving toward the Caribbean.?
> Europe, and USA stations, are lower in signal strength.
> ?
> Can often work?Caribbean and South American stations through a small 
> pile up when they are not working split.
> ?
> In my case it was a worth while 

Re: Topband: Bowtie Flags

[JC]

Hi Mark

Terminated loops are very old, the first patent belongs to Harold Beverage 

Harold Beverage invented wide band receiver antenna, loaded loop in 1941

https://docs.google.com/viewer?url=patentimages.storage.googleapis.com/pdfs/
US2247743.pdf

Most variations of this kind of antennas like this was used by military
during WWII. Some commercial versions started to come up on the 60's, Tom
W8JI worked the first JA using a similar RX antenna with multiple loops
phased end fire.

You see, the loaded loop is a Beverage antenna too.

73
N4IS


-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Don Kirk
Sent: Tuesday, December 13, 2016 2:08 PM
To: Mark Connelly 
Cc: topband 
Subject: Re: Topband: Bowtie Flags

Hi Mark,

I had no idea a terminated bowtie previously existed, but does not surprise
me.

Thanks for posting.
Don

On Tue, Dec 13, 2016 at 2:00 PM, Mark Connelly via Topband <
topband@contesting.com> wrote:

> As Nick undoubtedly knows, Bowtie antennas have been in use by medium 
> wave broadcast band DXers for some time now.
>
> One I tested here in 2010 is shown in this sketch:
> http://www.qsl.net/wa1ion/pictures1/bowtie_s_yarmouth.gif
>
> Some use a dual feedline scheme so the pattern can be reversed.  This 
> would be implemented by 16:1 transformers at each end if 50-75 ohm 
> coaxial cable is used or 9:1 transformers if using 90-150 ohm balanced 
> feed (CAT-5, speaker wire, two conductor zip / lamp cord, twisted pair 
> etc.) as recommended by Dallas Lankford and others.  In the balanced 
> feedline case, a 1.8:1 or 2:1 transformer (e.g. #73 binocular core 
> with 4 turns : 3 turns or 7 turns : 5 turns) is used in-shack to get 
> to unbalanced coaxial en route to the receiver / transceiver, RPA-1 or
similar amp, or phasing unit.
>
> Dual feedline split flag is another variant:
> http://www.qsl.net/wa1ion/pictures1/dual_feed_split_flag.gif
>
> Dual feedline antennas have a 4-pole 2-throw switch at the shack end 
> so either end can be switched to the receiver path and the opposite 
> end to a
> 250 or 500 ohm pot that facilitates in-shack null termination adjustment.
>
> Some people go with a single orientation antenna and put a preamp such 
> as the Wellbrook FLG100LN ( http://www.wellbrook.uk.com/FLG100LN-1 ) 
> right at the forward side.  This tends to overwhelm any feedline 
> pick-up (common-mode or otherwise) although common-mode choking is 
> still advisable near the antenna when longer runs (over 60m / 200 ft.) 
> of feedline are involved.
>
> In the case of a single orientation set-up, you then get to figure out 
> what termination end scheme is best.  These basically boil down to the 
> following options:
> (1) Fixed resistor in the 680-1200 ohm range either modelled / 
> guessed-at or determined by use of a potentiometer if it can somehow 
> be adjusted midway up the side of the antenna while monitoring a target
station to null.
> (2) "Vactrol" termination: a photoresistor adjusted by a DC voltage 
> applied on a control line from the shack: see page 9 of 
> http://www.durenberger.com/documents/PRESBT2016.pdf
> (3) Potentiometer adjusted by a motor drive: see 
> http://www.bamlog.com/ remotepotbox.htm
>
> My experience with the Bowtie I installed in 2010 was that it was 
> about
> 10-12 dB less sensitive than a Flag or Kaz Delta occupying the same 
> rectangular "box" of air space.
>
> Nulling off the back could be wider than that of a Flag but the 
> bandwidth at which the null stayed optimum at a particular terminating 
> resistance was not as wide as with the Flag (or its SuperLoop base-fed
variation:
> http://www.bamlog.com/superloop.htm ).
>
> Seeing that the MW broadcast band 530-1710 kHz has a greater max/min 
> frequency range ratio than the 1800-2000 kHz of 160m, issues that 
> might be problematic for broadcast DXers could matter a lot less on 160.
>
> Some of the perceived problems of low gain and null bandwidth could 
> easily have been cured by a combination of rigorous common-mode 
> choking as done on the Waller Flag ( 
> http://www.kkn.net/dayton2011/N4ISWallerFlag.pdf ) and high gain
at-antenna amplification.
>
> Mark Connelly, WA1ION
> South Yarmouth, MA
>
> <<
> Nick,?
>
> ?
> Although I did not measure it, the front to back, and front to side is 
> better, overall more quiet.
> ?
> It is receiving toward the Caribbean.?
> Europe, and USA stations, are lower in signal strength.
> ?
> Can often work?Caribbean and South American stations through a small 
> pile up when they are not working split.
> ?
> In my case it was a worth while change.
> ?
> The original plan was to be able to drive my car under it.
> ?
> 73
> Bruce-K1FZ
> ?
>
> On Mon, 12 Dec 2016 16:35:14 +, Nick Hall-Patch wrote:
>
> What specific improvements did you note when the Delta was raised Bruce?
>
> Thanks,
>
> Nick
> VE7DXR
> >>
> _
> Topband Reflector Archives - 

Re: Topband: Bowtie Flags

[wb6rse1]

Mark’s observation feeds my skepticism of a bowtie vs a flag in the specific 
circumstance where a ground independent RX antenna is your only option.

A bowtie would be about half the capture area of an equivalent “box” flag and 
consequently at a immediate disadvantage. If I was going to replace the flag 
with another ground independent design in about the same footprint, it would be 
a Waller flag.

73 - Steve WB6RSE

 
On Dec 13, 2016, at 11:00 AM, Mark Connelly via Topband 
 wrote:

My experience with the Bowtie I installed in 2010 was that it was about 10-12 
dB less sensitive than a Flag or Kaz Delta occupying the same rectangular "box" 
of air space.

_
Topband Reflector Archives - http://www.contesting.com/_topband

Topband: Bowtie Flags

[K1FZ-Bruce]

 
 
Earl, K6SE (sk)  advanced loop antennas on 160 meters. For 
information-See Page 34, July 2000 QST magazine. 
The small 160 meter bandwidth allows loop optimization k6SE gives 
dimensions. 
 
George Walter AA7JV  helped the TX3A Chesterfield DXpedition group 
with interconnected  two half delta loops. 
For more information  check "low Band DXing"  5th edition  page 7-106. 
 
Loop antennas optimized for the 160 meter band have been used in 
various folded loop   configurations for some time.. 
 

73
Bruce-k1fz
 


_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: Bowtie Flags

[Don Kirk]

Hi Mark,

I had no idea a terminated bowtie previously existed, but does not surprise
me.

Thanks for posting.
Don

On Tue, Dec 13, 2016 at 2:00 PM, Mark Connelly via Topband <
topband@contesting.com> wrote:

> As Nick undoubtedly knows, Bowtie antennas have been in use by medium wave
> broadcast band DXers for some time now.
>
> One I tested here in 2010 is shown in this sketch:
> http://www.qsl.net/wa1ion/pictures1/bowtie_s_yarmouth.gif
>
> Some use a dual feedline scheme so the pattern can be reversed.  This
> would be implemented by 16:1 transformers at each end if 50-75 ohm coaxial
> cable is used or 9:1 transformers if using 90-150 ohm balanced feed (CAT-5,
> speaker wire, two conductor zip / lamp cord, twisted pair etc.) as
> recommended by Dallas Lankford and others.  In the balanced feedline case,
> a 1.8:1 or 2:1 transformer (e.g. #73 binocular core with 4 turns : 3 turns
> or 7 turns : 5 turns) is used in-shack to get to unbalanced coaxial en
> route to the receiver / transceiver, RPA-1 or similar amp, or phasing unit.
>
> Dual feedline split flag is another variant:
> http://www.qsl.net/wa1ion/pictures1/dual_feed_split_flag.gif
>
> Dual feedline antennas have a 4-pole 2-throw switch at the shack end so
> either end can be switched to the receiver path and the opposite end to a
> 250 or 500 ohm pot that facilitates in-shack null termination adjustment.
>
> Some people go with a single orientation antenna and put a preamp such as
> the Wellbrook FLG100LN ( http://www.wellbrook.uk.com/FLG100LN-1 ) right
> at the forward side.  This tends to overwhelm any feedline pick-up
> (common-mode or otherwise) although common-mode choking is still advisable
> near the antenna when longer runs (over 60m / 200 ft.) of feedline are
> involved.
>
> In the case of a single orientation set-up, you then get to figure out
> what termination end scheme is best.  These basically boil down to the
> following options:
> (1) Fixed resistor in the 680-1200 ohm range either modelled / guessed-at
> or determined by use of a potentiometer if it can somehow be adjusted
> midway up the side of the antenna while monitoring a target station to null.
> (2) "Vactrol" termination: a photoresistor adjusted by a DC voltage
> applied on a control line from the shack: see page 9 of
> http://www.durenberger.com/documents/PRESBT2016.pdf
> (3) Potentiometer adjusted by a motor drive: see http://www.bamlog.com/
> remotepotbox.htm
>
> My experience with the Bowtie I installed in 2010 was that it was about
> 10-12 dB less sensitive than a Flag or Kaz Delta occupying the same
> rectangular "box" of air space.
>
> Nulling off the back could be wider than that of a Flag but the bandwidth
> at which the null stayed optimum at a particular terminating resistance was
> not as wide as with the Flag (or its SuperLoop base-fed variation:
> http://www.bamlog.com/superloop.htm ).
>
> Seeing that the MW broadcast band 530-1710 kHz has a greater max/min
> frequency range ratio than the 1800-2000 kHz of 160m, issues that might be
> problematic for broadcast DXers could matter a lot less on 160.
>
> Some of the perceived problems of low gain and null bandwidth could easily
> have been cured by a combination of rigorous common-mode choking as done on
> the Waller Flag ( http://www.kkn.net/dayton2011/N4ISWallerFlag.pdf ) and
> high gain at-antenna amplification.
>
> Mark Connelly, WA1ION
> South Yarmouth, MA
>
> <<
> Nick,?
>
> ?
> Although I did not measure it, the front to back, and front to side is
> better, overall more quiet.
> ?
> It is receiving toward the Caribbean.?
> Europe, and USA stations, are lower in signal strength.
> ?
> Can often work?Caribbean and South American stations through a small
> pile up when they are not working split.
> ?
> In my case it was a worth while change.
> ?
> The original plan was to be able to drive my car under it.
> ?
> 73
> Bruce-K1FZ
> ?
>
> On Mon, 12 Dec 2016 16:35:14 +, Nick Hall-Patch wrote:
>
> What specific improvements did you note when the Delta was raised Bruce?
>
> Thanks,
>
> Nick
> VE7DXR
> >>
> _
> Topband Reflector Archives - http://www.contesting.com/_topband
>
_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: Twist a Flag into a Bowtie?

[JC]

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 
Cc: 'topband' 
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 
>Cc: 'topband' 
>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 
> >Cc: topband 
> >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  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 - 

Re: 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:n...@ieee.org]
Sent: Monday, December 12, 2016 10:59 PM
To: JC 
Cc: 'topband' 
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 
>Cc: topband 
>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  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

Re: Topband: Twist a Flag into a Bowtie?

[JC]

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 
Cc: 'topband' 
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 
>Cc: topband 
>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  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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> >
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Nick Hall-Patch
Victoria, BC
Canada  

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