Sorry, the invention was in 1938 and the patent issued 1941
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of JC
Sent: Tuesday, December 13, 2016 6:28 PM
To: 'Don Kirk' <wd8dsb@gmail.com>; 'Mark Connelly' <markwa1ion@aol.com>
Cc: 'topband' <topband@contesting.com>
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-bounces@contesting.com] On Behalf Of Don Kirk
Sent: Tuesday, December 13, 2016 2:08 PM
To: Mark Connelly <markwa1ion@aol.com>
Cc: topband <topband@contesting.com>
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 +0000, Nick Hall-Patch wrote:
>
> What specific improvements did you note when the Delta was raised Bruce?
>
> Thanks,
>
> Nick
> VE7DXR
> >>
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