Building The Stealth Hawk TV Antenna (See Post #304) - Page 25 - Canadian TV, Computing and Home Theatre Forums

ota_canuck · 2010-12-30, 06:03 PM

jakeru ,

That's pretty good for an indoor antenna installation. A small amplifier/booster may help to get a better lock on some of those problem channels. If you can get that antenna outside, that would be even better.

Nopaytv · 2011-01-03, 10:23 AM

I built a new double diamond stealth hawk antenna using #4 copper wire and am calling it the Mantis. The other one worked ok, but the wire was thinner and the legs were different. In this version, I modified the legs so that there is a diamond within a diamond (fractalized?). I have not tested the antenna yet. Anyone care to model it?

http://www.digitalhome.ca/forum/album.php?albumid=666

The top diamond is 7" on each side, the gap is 1", and the height is 5". The diamond below is 9.5" on each side, the feed gap is 2", and the height is 13.5". The dimensions in the legs are 9.5", 9.5", 7", 3.5", 3.5".

loveota · 2011-01-08, 09:47 AM

Swr isn`t that bad but alittle high on the bottom of the UHF band . Gain shows @ 5-7 dbi . The signal patterns aren`t so great caused by way too much wire below the feedpoints . You would be better off eliminating whats below the feedpoint and mirror the top diamond. Gain would be the same , better SWR and the pattern would be consistant from bottom to top of the band.
Never stop trying.

Nopaytv · 2011-01-08, 09:57 AM

loveota, thanks for the modelling. The feed point is actually the 2" gap below the 1" gap. There is equal amounts of wire above and below the feedpoint. Sorry if I didn't make that clear in the post.

guizmo1967 · 2011-01-08, 05:35 PM

Just to share my experience, I had a DIY bowtie combined with a GH10 and now I only have a Stealth Hawk optimized and I get all channels as before !!!

This is by far the best DIY antenna you can build and it's the cheapest.

I did mine with a aluminium flat bar 3/4 x 1/8

Nopaytv · 2011-01-08, 06:20 PM

Here is the Mantis with the balun attached to the feedpoint:

http://www.digitalhome.ca/forum/albu...pictureid=3415

ota_canuck · 2011-01-08, 08:43 PM

lovota.

This looks very interesting!

How did it look for VHF results? Can you revise that feedpoint and repost the results for midVHF and midUHF?

loveota · 2011-01-09, 08:24 AM

My Bad on the feedpoint location . I re-located the feedpoint . Looks better but the patterns still don`t look promising . Vhf is compareable to the Stealth Hawk however the SWR is very low . Mind you I didn`t optimize the AGT for this . That one is time consuming and I do that in final tweeking . Not a huge difference that I`ve seen so far anyway. This is just showing a rough idea.
I didn`t want to flood this thread so you can view a few sample patterns here
http://www.digitalhome.ca/forum/album.php?u=71446 .
I tried a couple things . Opening the top made matters worse. Removing the top diamond Made UHF-low better , Hi was worse.
What does look promising with this design is removing the top diamond , with what is left , leave the top open . Not good for VHF but UHF shows a pattern in the shape of an "X" ( 4 lobes) all the way through the UHF band . This can be very benificial to some areas . This would be somewhat similiar to my multi-lobed GH which is a big hit on each end of Lake Erie , North shore. Soon as the snow melts it will be tested in Longpoint (central north shore) . I think it would be worth my time tweeking this pattern and do some comparisons and fieldtesting to the multi-lobe GH .

Nopaytv · 2011-01-09, 12:08 PM

Thanks loveota, I appreciate your efforts so much. If we remove the top diamond the amounts of wire above and below the feedpoint wouldn't be equal. I think ota_canuck's research on the stealth hawk determined that that was very important. If the top diamond was removed what kind of tweak do you think could be done to make the top and bottom equal in wire length?

ota_canuck · 2011-01-09, 12:50 PM

Hmmm! The picture numbered 6 of 8 [the one that looks like Dolly Partons profile]

http://www.digitalhome.ca/forum/albu...pictureid=3421 seems to have some merit, however it also seems to demonstrate that the top diamond is a none contributor to the design.

I believe that lovota has previously discovered that closed top diamond is beneficial to VHF but at a slight cost to the UHF gain. The SWR as I recall can be fine tuned by slightly increasing or decreasing the feed gap distance once the UHF/VHF balance has been acheived. Raw gain matters but it 'is not' the most important factor.

That X pattern certainly would comply with the intended multidirectional purpose of the Stealth Hawk designs. Directional and bi-directional antenna requirements are already quite capable characteristics of the many bowtie and GH designs. The most important focus of the SH design is to balance UHF&VHF in a multidirectional pattern even if it means sacrificing a bit of overall raw gain.

Yes,.. in early Stealth Hawk trials, the equal top/bottom wire mass seemed to have the most desirable results, but that is not gospel. Don't be afraid to 'think outside of the box' because what works well for previous SH iterations may not be beneficial to newer creations of SH designs.

I would suggest focusing on reducing the lower wire mass on the one shown in picture number 1 http://www.digitalhome.ca/forum/albu...pictureid=3427

[just my personal opinion based on what I've previously experience throughout my own trial and error builds]

loveota · 2011-01-10, 10:24 PM

With these changes I was able to bump the gain up a tad and lower the SWR on most freq. Again this is for the " X " pattern throughout the UHF band. Forget about VHF unless you`re very close to the towers. If thats the case this design would be bi-directional off the sides . Combine the E.D. 100 as VHF with it.

ota_canuck · 2011-01-10, 10:47 PM

Using a cm7777 in the separate input mode with this Mantis for UHF only and then adding a simple VHF dipole design mounted below for VHF would make a good combo.

loveota · 2011-01-10, 11:03 PM

Or this .

ota_canuck · 2011-01-10, 11:16 PM

Yeah! The Eden 100 had 3+db on VHF

Nopaytv · 2011-01-11, 02:19 PM

ota_canuck has said that stealth hawks don't perform well with anything above them. Do you think that I should place my already built Eden below the mantis and hook them up to the vhf and uhf inputs on the cm7777 as described?

2010-12-30, 06:03 PM	#361
ota_canuck Veteran Join Date: Mar 2009 Location: Dunnville, Ontario on the Grand River, North shore Lake Erie Posts: 2,406	jakeru , That's pretty good for an indoor antenna installation. A small amplifier/booster may help to get a better lock on some of those problem channels. If you can get that antenna outside, that would be even better. __________________ 3D SSH III with ZZ4 refl. http://imageshack.us/user/jmsdigital

2011-01-08, 08:43 PM	#367
ota_canuck Veteran Join Date: Mar 2009 Location: Dunnville, Ontario on the Grand River, North shore Lake Erie Posts: 2,406	lovota. This looks very interesting! How did it look for VHF results? Can you revise that feedpoint and repost the results for midVHF and midUHF? __________________ 3D SSH III with ZZ4 refl. http://imageshack.us/user/jmsdigital

2011-01-09, 12:50 PM	#370
ota_canuck Veteran Join Date: Mar 2009 Location: Dunnville, Ontario on the Grand River, North shore Lake Erie Posts: 2,406	Hmmm! The picture numbered 6 of 8 [the one that looks like Dolly Partons profile] http://www.digitalhome.ca/forum/albu...pictureid=3421 seems to have some merit, however it also seems to demonstrate that the top diamond is a none contributor to the design. I believe that lovota has previously discovered that closed top diamond is beneficial to VHF but at a slight cost to the UHF gain. The SWR as I recall can be fine tuned by slightly increasing or decreasing the feed gap distance once the UHF/VHF balance has been acheived. Raw gain matters but it 'is not' the most important factor. That X pattern certainly would comply with the intended multidirectional purpose of the Stealth Hawk designs. Directional and bi-directional antenna requirements are already quite capable characteristics of the many bowtie and GH designs. The most important focus of the SH design is to balance UHF&VHF in a multidirectional pattern even if it means sacrificing a bit of overall raw gain. Yes,.. in early Stealth Hawk trials, the equal top/bottom wire mass seemed to have the most desirable results, but that is not gospel. Don't be afraid to 'think outside of the box' because what works well for previous SH iterations may not be beneficial to newer creations of SH designs. I would suggest focusing on reducing the lower wire mass on the one shown in picture number 1 http://www.digitalhome.ca/forum/albu...pictureid=3427 [just my personal opinion based on what I've previously experience throughout my own trial and error builds] __________________ 3D SSH III with ZZ4 refl. http://imageshack.us/user/jmsdigital

2011-01-10, 10:47 PM	#372
ota_canuck Veteran Join Date: Mar 2009 Location: Dunnville, Ontario on the Grand River, North shore Lake Erie Posts: 2,406	Using a cm7777 in the separate input mode with this Mantis for UHF only and then adding a simple VHF dipole design mounted below for VHF would make a good combo. __________________ 3D SSH III with ZZ4 refl. http://imageshack.us/user/jmsdigital

2011-01-10, 11:16 PM	#374
ota_canuck Veteran Join Date: Mar 2009 Location: Dunnville, Ontario on the Grand River, North shore Lake Erie Posts: 2,406	Yeah! The Eden 100 had 3+db on VHF __________________ 3D SSH III with ZZ4 refl. http://imageshack.us/user/jmsdigital

2011-01-03, 10:23 AM	#362
Nopaytv Join Date: Jun 2010 Posts: 50	I built a new double diamond stealth hawk antenna using #4 copper wire and am calling it the Mantis. The other one worked ok, but the wire was thinner and the legs were different. In this version, I modified the legs so that there is a diamond within a diamond (fractalized?). I have not tested the antenna yet. Anyone care to model it? http://www.digitalhome.ca/forum/album.php?albumid=666 The top diamond is 7" on each side, the gap is 1", and the height is 5". The diamond below is 9.5" on each side, the feed gap is 2", and the height is 13.5". The dimensions in the legs are 9.5", 9.5", 7", 3.5", 3.5".

2011-01-08, 09:47 AM	#363
loveota Join Date: Aug 2009 Location: Eden Ontario Posts: 213	Swr isn`t that bad but alittle high on the bottom of the UHF band . Gain shows @ 5-7 dbi . The signal patterns aren`t so great caused by way too much wire below the feedpoints . You would be better off eliminating whats below the feedpoint and mirror the top diamond. Gain would be the same , better SWR and the pattern would be consistant from bottom to top of the band. Never stop trying.

2011-01-08, 09:57 AM	#364
Nopaytv Join Date: Jun 2010 Posts: 50	loveota, thanks for the modelling. The feed point is actually the 2" gap below the 1" gap. There is equal amounts of wire above and below the feedpoint. Sorry if I didn't make that clear in the post.

2011-01-08, 05:35 PM	#365
guizmo1967 Rookie Join Date: Dec 2010 Posts: 9	Just to share my experience, I had a DIY bowtie combined with a GH10 and now I only have a Stealth Hawk optimized and I get all channels as before !!! This is by far the best DIY antenna you can build and it's the cheapest. I did mine with a aluminium flat bar 3/4 x 1/8

2011-01-08, 06:20 PM	#366
Nopaytv Join Date: Jun 2010 Posts: 50	Here is the Mantis with the balun attached to the feedpoint: http://www.digitalhome.ca/forum/albu...pictureid=3415

2011-01-09, 08:24 AM	#368
loveota Join Date: Aug 2009 Location: Eden Ontario Posts: 213	My Bad on the feedpoint location . I re-located the feedpoint . Looks better but the patterns still don`t look promising . Vhf is compareable to the Stealth Hawk however the SWR is very low . Mind you I didn`t optimize the AGT for this . That one is time consuming and I do that in final tweeking . Not a huge difference that I`ve seen so far anyway. This is just showing a rough idea. I didn`t want to flood this thread so you can view a few sample patterns here http://www.digitalhome.ca/forum/album.php?u=71446 . I tried a couple things . Opening the top made matters worse. Removing the top diamond Made UHF-low better , Hi was worse. What does look promising with this design is removing the top diamond , with what is left , leave the top open . Not good for VHF but UHF shows a pattern in the shape of an "X" ( 4 lobes) all the way through the UHF band . This can be very benificial to some areas . This would be somewhat similiar to my multi-lobed GH which is a big hit on each end of Lake Erie , North shore. Soon as the snow melts it will be tested in Longpoint (central north shore) . I think it would be worth my time tweeking this pattern and do some comparisons and fieldtesting to the multi-lobe GH .

2011-01-09, 12:08 PM	#369
Nopaytv Join Date: Jun 2010 Posts: 50	Thanks loveota, I appreciate your efforts so much. If we remove the top diamond the amounts of wire above and below the feedpoint wouldn't be equal. I think ota_canuck's research on the stealth hawk determined that that was very important. If the top diamond was removed what kind of tweak do you think could be done to make the top and bottom equal in wire length?

2011-01-10, 10:24 PM	#371
loveota Join Date: Aug 2009 Location: Eden Ontario Posts: 213	With these changes I was able to bump the gain up a tad and lower the SWR on most freq. Again this is for the " X " pattern throughout the UHF band. Forget about VHF unless you`re very close to the towers. If thats the case this design would be bi-directional off the sides . Combine the E.D. 100 as VHF with it.

2011-01-10, 11:03 PM	#373
loveota Join Date: Aug 2009 Location: Eden Ontario Posts: 213	Or this .

2011-01-11, 02:19 PM	#375
Nopaytv Join Date: Jun 2010 Posts: 50	ota_canuck has said that stealth hawks don't perform well with anything above them. Do you think that I should place my already built Eden below the mantis and hook them up to the vhf and uhf inputs on the cm7777 as described?

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