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Just did a scan and vhf 5 was audio only , 21 ch. between 6 & 69 very watchable picture if not near perfect. There were about 4 more with audio only. I also did a scan on digital ( been awhile ) and came up with some tropo stations up to 133 miles away from Ohio and Detroit . I was just testing a GH Wideband elements only and this thing is kicking it to pcs .
Now you mention the flatbar, that would be the way to construct this ant. The 1/4" rod is alittle tricky to hold proper postion. I`ll try the flatbar aswell this week and compare it to the 1/4" rod model and see if that brings my uhf up abit . Now would the 10" measurements with the flatbar be center to center?
 

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1/2 GH???

Very interesting...If it is down to 8" leg, then this antenna looks like SBGH get chopped into 1/2, I'll call it 1/2GH.

I'll make one and try it out since I have all the materials handy.
 

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Discussion Starter #23
All GH's, bowtie's, centipede's, etc.... :eek: They are all based on Chireix's diamond shaped antenna theories.

Pretty much!,... most of the antennas found in these threads are indeed similarly based on basic diamond element designs,... except for the fact that the bends/gaps in this one must be kept in the format of the squatty diamond and the bottom legs must resemble the geometry of the upper diamond's shape. The gap between the tips of the elements must be 2", so the actual angle at the bends within the diamond will be determined by whatever bend degree/radius you need to achieve that 2" gap.

The gap at the feed point can be 2" - 3" and the segmented leg lengths can be anywhere from 7" - 10" depending on what raw element material lengths are readily available [that's the length range that I have tried so far and it seems to be a safe range to work within]. It seems to be the balance of the geometric shape that makes it work, not the size of the element lengths.
 

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Beware of Tropo Ruining Your Test Results

Let's be very careful about our testing, folks. Some of you are in Southern Ontario tropo zones, and there have already been some doozies this year. My advice is to check for tropo events in order to try to avoid them while testing - see this thread: OTA DXing, Tropo, Odd Reception, Weird Weather: 2010

And of course Mr. Hepburn's wonderful prediction site is very accurate for tropo events around the world: http://www.dxinfocentre.com/tropo.html
 

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ION is my challenging channel from my location. I have a dedicated XG91 for it to get somewhat consistent reception, winter days is completely off.

If this antenna can outperform my XG91, I'm hat's off to you..Heck, I might even start build them for my neighbors.
 

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FWIW, I spent a few minutes building and testing one of these last night since I've run out of other types to build :). Here in the pretty much non tropo-influenced Vancouver area, it didn't work for me. I did receive my local analogs quite well, but the 5 Mt. Seymour digitals from my deep fringe location (47 mi., 2-edge, and all ~< -11NM) did not even register (see TV Fool below - 2 channels not yet in TV Fool).

http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d9c6b9e99d458f9

It was worth a shot but fortunately it was only wishful thinking. Anything more and I would have suspected some type of black magic... Let's hope it keeps working for those that have gotten good results for their situations!
 

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Discussion Starter #27
zapperman
WoW! Your tvfool looks quite a scattered and sparse market.:eek:

This antenna won't work in every situation, nor will any other antenna work in every situation. Like 300ohm has said, it's all about location, location, location. If the market isn't there, an antenna won't fix it. There are no silver bullets.

Pretty much anything 50-60 mile+ would most likely be tropo or due to some sort of favourable conditions. Any omni/bi-directional antenna has it's limits. Most omni antennas that I've ever seen or tried are usually only good for 20-30miles.

I get Cleveland stations quite frequently, sometimes lasting for a whole day, but at that distance, I would never expect them to be reliable to consider them as being regular obtainable reception markets.

It's almost impossible to install/aim and evaluate any antenna during tropo events, so discount anything 50miles+ that seems impossible as being inaccurate results.
 

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zapperman
WoW! Your tvfool looks quite a scattered and sparse market.:eek:
Yeah, I didn't expect this to outperform my existing setup (modded orig 4228 +7777), which CAN get most of those digitals, but I was curious about what it *would* get. Besides, I had a coworker in mind that is a little more suburban than me for which this antenna may be appropriate, especially given its small footprint and corresponding low WAF... :).
 

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To be fair, zapperman's house is where OTA signals go to die. :D
Yeah, yeah, yeah. Who said I wan't up for a challenge... I think the fact that I'm getting anything at all qualifies my as some sort of "signal whisperer". Good thing the neighbours that see me late at night and say "look, there's that guy up on his roof with his laptop again..." don't really see me talking to my 4228 :).
 

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I recognize Stealth Hawk as being the old Chireix 2-Square, except with the
bottom two legs splayed directly outwards:
http://imageevent.com/holl_ands/chireix/chireix
Although the UHF Gain runs circles aroung the Stealth Hawk, the 2-Square Chireix
has slightly negative Gain in the Hi-VHF band (so I didn't upload charts).

Recall that the old Hoverman is a 4-Square Chireix with the top and bottom legs
splayed directly outwards:
http://imageevent.com/holl_ands/grayhoverman/hovermantype1
Both UHF and Hi-VHF Raw Gains are considerably more than the Stealth Hawk,
but Hi-VHF SWR is a pathetic 20 or so across the entire band....a bit more
that Stealth Hawk's very poor Hi-VHF SWR....

Stealth Hawk has poorly formed, multi-lobed UHF Azimuthal Patterns,
esp at higher frequencies, where the SWR is ALSO increasing, reducing Net Gain.
Hi-VHF Gain is only so-so, with excessive SWR ranging from 14 down to 7:
http://imageevent.com/holl_ands/chireix/stealthhawk

SBGH WW-X0418-Mod0 is a higher Gain Omni-directional antenna, as was
discussed a while ago in Area 51:
http://imageevent.com/holl_ands/grayhoverman/widebw [Slides 46-54.]
Free Space Gain is nearly 6 dBi for Horizontally Polarized signals but
Hi-VHF SWR is even worse...about 30-40 across the Hi-VHF band.
[Can't use Vertical Dipole for DTV until more stations broadcast Circular Polarization.]

UHF Six-Whisker Bowtie is a good, simple to build Bi-directional antenna.
UHF 2-Bay Bowtie is even better and would still be almost as simple to build
as the Stealth Hawk but will provide a LOT more UHF Gain with slightly
better Hi-VHF performance:
http://imageevent.com/holl_ands/dipoles/uhfbowties
http://imageevent.com/holl_ands/multibay/uhf2bays/uhfm2
[These latter two results webpages are ALL NEW RESULTS....]

And of course, an M4 Super-4-Bay with NO Reflector works well for BOTH
UHF and Hi-VHF, without any SWR problems:
http://imageevent.com/holl_ands/multibay/4bay/superm4

But if you want the SIMPLEST, GOOD antenna for BOTH UHF and Hi-VHF
I think separate antennas and a UVSJ combiner might be easiest, such
as a UHF Loop plus a Hi-VHF Loop a few feet below:
http://imageevent.com/holl_ands/loops

Let me see, is there anything I haven't mentioned???
Oh Yeah, a couple others on the Loops webpage:

SBL - Shorted-Bowtie-Loop, NO Reflector (Hi-VHF Gain=3 dBi, but SWR is excessive 23-7).

BIL - Bowtie-In-Loop, NO Reflector
with moderate Gain on both UHF and Hi-VHF with SWR under 3.4:
http://imageevent.com/holl_ands/loops/bilnorefl
This is NEW UPLOAD of what I've done so far....it's a very tricky antenna and might not yet be "optimum".

Note that when a reflector is added to the BIL, it gets a LOT better for both UHF and Hi-VHF....
 

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Nice work Holl_ands, thanks for posting! Particularly enjoyed the 2-bay data. I have played with a 10x9.5 two bay with 1-3/4" spacing between phase lines (12 guage wire). Mclapp told me that two bay performance is better with 1-3/4" spacing rather than narrower such as 1-1/4". I roughly measured effects of aiming 35 degrees off axis for ch 15 and ch 36. The change in dropout margin matches your polar plots exactly for both channels! :) Your model appears to be spot on!
 

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Discussion Starter #34
Even within any of the bowtie designs, Chireix's diamond pattern is invisibly active within the spaces between the xbays. That is why element spacing, angles and gap distances are so critically influential to all of these flat panel style antennas.

eg; Bowtie antennas
In between the top 2 bowties and in between the bottom 2 bowties on a 4bay antenna, you will see active air spaces that are a small diamond shape. In between those pairs of bowties, at the feed point, there is a larger active air space that is in a diamond shape. whether it's an open loop or closed loop element design, Chireix's diamonds can be found somewhere on flat panel antennas.

X <1st bowtie
small diamond air space between top two bowties
X <2nd bowtie
larger diamond air space in middle at the feed point
X <3rd bowtie
small diamond air space between bottom two bowties
X <4th bowtie

___________________________

With that theory of active air space in mind,.. the Stealth Hawk has three diamond air spaces in play.
One within the diamond shaped elements on the top half, and one invisible diamond on either side of the bottom half.

My theory is that the single diamond at the top is dimesional to UHF and the two at the bottom are working together to enhance VHF.

The top diamond is made of four 7"segments in an enclosed form [7" being dimensional key to the UHF spectrum]
Bottom elements splayed outwards are 7"or 8"segments x four segments [28" to 32" is the key to the VHF-hi spectrum]

Problems: SWR? Finding the correct balance of the air space of those invisible diamonds.

:p maybe I have too much air space between my ears, but that is my theory and I'm stickin 2 it... :p


_______________________________________________

Einstien quotes;

"Any intelligent fool can make things bigger, more complex, and more violent. It takes a touch of genius -- and a lot of courage -- to move in the opposite direction."
"Imagination is more important than knowledge."
 

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Discussion Starter #35
I did some tweaking [thought&hack mods] on the flatwire elements
to try and improve on some higher UHF [for better 50.1 reception]
without losing any VHF 12.x.

I hacked the top element segments down to 7" lengths.

Seems to have helped somewhat.




Quick test results from tonight:

digital: 2.x, 4.1, 5.1, 7.1, 9.1, 11.1, 12.x, 15.1, 17.x, 23.1, 24.1, 26.x, 29.1, 36.1, 44.1, 49.1, 51.x, 54.x, 66.1

Plus some strong tropo from cleveland 3.1/.2, 8.1, 61.1, 43.2/.3, 5.1

WEWS 5.1psip[17.1RF] was trying to kick CBC[20.1RF] off the 5.1psip,so I had to rescan to get CBC back.
 

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Nothing tropo about my Erie stations . I have 18 miles of land to see through then 40 + miles of water . This Hawk is still holding ground day and night on the Erie stations. With the rotor working again i was able to improve ch 35 abit more and found ch 54 ( digital 50 ) in a wierd position but not strong enough for a clear picture .
I`ve been testing different GH elements "Only" and the GH8 was very strong on digital 50 , the other Eries were more than strong enough except digital 12 was rather weak. I think combining the GH8 elements and this Hawk at the top into my CM7777 would be MY perfect solution to a reflectorless ant. That would be much more efficient in several ways. Hopefully they wont interfere with eachother . Will find out in a day or 2 .
 

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It was a perfect day for playing outside . I joined my GH8 elements and the Stealth Hawk on the mast . I tested the GH elements first to see if anything changes with both ant. together . With both combined ( Hawk to vhf input ) through the CM7777 Ch 12 was still very strong, 24 dropped 5% , 35 stayed the same , 54 dropped 5% but still more than enough signal and 66 increased 5% .All my analogs are still there with good picture. This is what i`ve been looking for , something reflectorless that covers digital 12 & 50 and everything inbetween with virtually no need to touch the rotor . My XG 91 was tops for signal strength but was a real pain tuning from 1 ch to another. Next is to make permanent hardware for mounting it all, put it back up and forget about it.
This Steath Hawk complimented my GH perfectly .
Keep up the good work ota_canuck !

 

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I added some Feedline Separation parameter sweeps at three UHF freqs for the 2-Bay:
http://imageevent.com/holl_ands/multibay/uhf2bays/uhfm2
I like to say "Quasi-Optimized"....cuz it all depends on WHAT you want to optimize and the
tradeoffs in performance you're willing to accept....

To minimize SWR, considering worst-case frequency (698 MHz), FeedlineSep should be about 1-inch...
To maximize Gain, 1-inch is also best at 602 and 698 MHz, but Gain falls off a few tenths at 470 MHz....

So I think the "best" compromise" is somewhat larger than 1-inch, so looking at the Gain chart
at 470 MHz and all SWR Charts, I picked 1.5-inch for "Quasi-Optimum" Feedline Separation.

A few tenths of an inch one way or another doesn't cause very much difference....
So if you like 1.25 or 1.75-inch...that's still in the "Quasi-Optimum" ballpark.....
 

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Chireix and Hoverman patents stipulate 45-degrees angles for the zig-zag elements.
However, I found the Chireix provided slightly higher Gain at 40-degrees.

It appears the angle of the elements (wrt horizontal plane) in the Stealth Hawk is close to 30-degrees.
Was this the "best" angle for this antenna????
 

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Discussion Starter #40
Chireix and Hoverman patents stipulate 45-degrees angles for the zig-zag elements.
However, I found the Chireix provided slightly higher Gain at 40-degrees.

It appears the angle of the elements (wrt horizontal plane) in the Stealth Hawk is close to 30-degrees.
Was this the "best" angle for this antenna????
I started with 45deg bends, thinking that was the optimum for Chireix squares according to many posts that I've been reading. The problem at 40-45deg is that I can't seem to pick up 50.1RF. Out of frustration, I slammed the angle all the way to 30deg and wella, it worked. I was thinking that the separation at the tip has to be 1-2", whereas with the angles set at 45deg, that separation becomes 3.5" and then I lose the higher freqs. Maybe the angle can be increased to 40deg and the upper segments can be extended to keep the element separation at 1-2" apart. It seems that a squatty diamond shape gets better reception distance.

My objective behind this design is 7-51 UHF/VHF/OMNI/with lower threshold for stray interferences : basically I'm looking for 7-51 omni directional performance that will cover 40-60miles, but low enough on the gain that all the rouge interferences that I experience will disapear. High raw antenna gain doesn't seem to mean much unless your targeting with a rotor at 100 mile markets. Me thinks that, sometimes less is more.

This experiment has proven that higher raw gain is not the be-all and end-all of antenna performance. I have found that higher gain antennas such as the GH, centipede designs don't do well because of all the local interferences that cause pixelation, so if a low gain can get me 40-60 mile reception, then I'm better off to keep trying to develop an optimum low gain antenna design.

Maybe working on development of a quiet antenna with lower gain and balanced SNR is the key to finding the optimum digital reception.
 
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