It's time to start working on the UHF/VHF 'Super-Hawk' [the next generation]
Vertical Stacked SH--> one up + one down, but where to put the balun feed points?
Option A] Center fed with a 4" gap at the 4:1 balun feed point .
Option B] Upper & lower fed using 2" feed gaps and phase lines with the 4:1 balun at the center point of the phase lines?
Feed gap:
Option A] 4" gap at center feed
Option B] 2" feed gaps using phase lines
Element leg spacing & heights will remain the same as the SH#289 design.
Leg lengths from top to bottom of the individual left element & right element:
15", 6.5", 8.5", 8.5", 6.5", 15"
All bends are approx. 85° bends
The four [top/bottom/left/right] 15" legs stick outward at approx 45°
I'm going to run a hard-test mock-up version first to see if it even works, then I'll post a sketch for the DHC's NEC gurus.
It probably will become more directional than omni/multi-directional.
Super Hawk (two Stealth Hawk#289 antennas combined)
Built this new improved antenna to defy all that media rubbish about
"rabbit-ears won't work anymore"
Well, I certainly didn't feel like messing around with just the rabbits ears, so rather than waste anymore effort disputing the rabbit-ear theory , I have used the theory of the Stealth Hawk design and built myself the world's first DTV-Rabbit antenna and it works just awsome.
So,... here's the debut of the GH&SH_hybrid VHF/UHF antenna!
Note: Each side is made of one continuous 60" strip of #10 galvanized merchant wire.
No, it's an outdoor or attic size that is a bit of a hybrid of the Hoverman&Stealth antennas.
I stated that I "didn't feel like messing around with just the rabbits ears", so I built the whole damn bunny,.. it was a 'pun' related to media's recent 'rabbit ears are obsolete' misinformative reporting
No, it's not rabbit ears
So,... here's the debut of the GH&SH_hybrid VHF/UHF antenna!
I just built these Super Hawk#473 elements yesterday afternoon to do an initial trial-test run to check out if my theory of combining two Stealth Hawk#289 antennas would work.
Yes it is doing very well on both VHF & UHF reception.
The single-bay Stealth Hawk and the classic Stealth Hawk designs of the past did not work with reflectors, but I suspect that this 2bay design just might be workable with a reflector. My goal is to build an antenna that is multi-lobed, multi-directional with a wide enough beam-width to eliminate the need for a rotor, therefore the use of reflectors were not in my planned testing.
I currently have it mounted on my shop at 20ft and I get much stronger overall reception than I did with the single-bay Stealth Hawk antenna. This thing still seems to have quite a wide beam-width, with the signal strengths coming in stronger, though I expect that this antenna will prove to be more bi-directional than multi-directional. If someone models this design, with/without reflectors, we'd probably find some need for additional frequency tuning and SWR optimization.
I am interested in the new design. Please can someone mock it up and post the nec file to see it all. Been looking at what new design I want to try (either the GH6n3 or this design for fun).
Yeah, it's similar to that Hoverman element design, but with the Stealth Hawk #289 leg & bend-angle dimensions. The result is this Super Stealth UHF & VHF antenna with a very wide beam-width found during initial real-life test performance.
The SH design criteria is:
UHF channels 14-51,
VHF channels 7-13,
Very wide-beam bi-directional or, multi-directional, or omni-directional.
I don't know what the beam-width configuration is. This antenna has not been modeled yet.
I have done many antenna tests at my location GH,M4,4221,HBU33, etc,.. and the SH289 outperformed them all in my area. I need a very wide beam-width to cover the scattered broadcast market. The GH,M4, etc are not comparable because they are too directional compared to the SH antennas.
Super Stealth antenna vs the SH289 antenna:
From the real-tests I've done so far, I would quess that this 2bay design has very similar multi-lobe characteristics as the single bay SH antenna design, but the signal strengths are a bit stronger. It appears to be full range for VHF-Hi & UHF
Yup, I have that antenna. I re-discovered it in my basement a few weeks ago, and then when I saw the diagram of the antenna in this thread I thought - wait a minute, I've seen that before - and I unfolded it and took that picture. Do you want me to measure it? It's never been used. It still has the tag on the lead connector screw.
The pattern is a standard figure 8 pattern, except where the gain goes below 4 and then it becomes multi-lobed. So in that aspect, youre no better off than a single SH 289.
Is it possible to tame the SWR with feed gap adjustments, eg: reduce the feed gap to 1.5".
The classic stealth hawk antenna had a 1" gap at the top end [or no gap in some models] which seemed to help with VHF gain. That top end is now being used as the feed point in this double SH design.
Vertical Stacked SH--> one up + one down, but where to put the balun feed points?
Option A] Center fed with a 4" gap at the 4:1 balun feed point .
Option B] Upper & lower fed using 2" feed gaps and phase lines with the 4:1 balun at the center point of the phase lines?
Feed gap:
Option A] 4" gap at center feed
Option B] 2" feed gaps using phase lines
Reducing the feed gap from 3" to 1.5" makes the uhf SWR a bit better but reduces uhf gain a bit.
For vhf-hi, its the opposite, it increases the vhf-hi swr but increases vhf-hi gain a bit.
For stacking the SH, the Winegard SD3700 300ohm to 75ohm outdoor coupler may be the ticket. With it, you could tweak out the spacing between the two and adjusting directions for sidelobes without having to worry about phasing lines.
The vhf-hi net gain, while negative, doesnt mean you wont get the very strong stations. The crappy rubber ducky antennas sold with portable TVs and some pc tuner cards also have negative net gain.
The tophat spacing is 1" from the elements. When its 1/2" apart there is lower SWR but it affected the top half of the UHF band abit more than what 1" did to the UHF . Some time tweeking would be needed to flatten out the SWR across the band . However at 195 Mhz there is a beamwidth of 84 degrees . Very impressive .
This looks pretty wild when you get to the higher UHF ranges. Maybe the legs lengths are too long. The UHF range needs to be centered a little higher to bring the drop-off a bit closer to 700Mhz.
UHF Gain:
VHF Gain:
I will attempt adding the top-hat [using 1" gap] on my test antenna tomorrow.
Centering the UHF range a bit higher:
I think the 3" center feed gap and the upper & lower element spacing gap is OK, but maybe the leg lengths should be shortened from 15", 8.5", & 6.5" to 14",8",6" to shift the UHF range up a notch to get the UHF curve centered better. I had expected that the gain would have been a bit low at ch14 and then ramp up throughout the mid range and then drop off again at ch51.
I seem to recall, with other experimental trials, that the total wire length of an integrated element effects the center of the UHF range. I believe that 56" was the magic number for centering the UHF range. Maybe I will build a new pair of elements using 1/2" shorter leg lengths @ [14" 8", 6", 6", 8", 14"] [that would be 56" total wire length per side]
The one you posted is with the 1/2" spacing . This is the 1" spacing . I need to label those pics yet .
Without the tophats there is an issue from 590Mhz to 660Mhz where the pattern is moreso out the top and bottom rather than out the front and back . Here`s the worst case .
This needs to be corrected . Off hand I dont know what It`ll take to fix that . Once done the tophat would change aswell . Unfortuately I`m starting to re-do my roof today so time isnt there to play around with it . I`d take a good look at 300ohm`s idea of the SD3700 and do some calculations on which would give the best gain .
I haven't tried the top-hat yet, but I did make two new elements using the shorter leg lengths.
The revised leg lengths are:
14", 8", 6" [3" gap feed-point] 6", 8", 14" = 56"total wire length per element.
Initial trial results of this shorter wire length demonstrates a slight shift upward in the UHF range. I can now get WNYO49RF and I still get WUTV14RF.
There was a significant drop around channel 40 with the longer legs, and now I can get Global Toronto41RF.
Note: Global Toronto41RF and WNYO49RF have been difficult to catch from my shop location. Signals are restricted by two groups of tall pine trees.
Using NARODS:
I will try loveota's top-hat @1" gapped narod design this afternoon and I'm going to try a similar test using a 'V' shaped narod.
I tried the narod idea, but it resulted in significant signal losses and flutter across the UHF band and it didn't show any improvement on VHF. CHCH 11RF and CTV 9RF actually lost some signal strength.
With the antenna made with shorter legs and no-narods, I get better UHF range and I can also actually get a signal from Global 6.1 Paris. That's the first time I've ever seen Paris 6.1 since the transition. With the shorter legs, I can also get 49.1, which is the highest RF channel available in my area right now. WQLN broadcasts on 50RF, but they are either off-the-air or on their low power backup antenna again today.
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