Yes,.. Stealth Hawk aiming can be tricky until you understand the variables of the gain contours of the SH's multidirectional antenna characteristics.

Perhaps this could assist with your Stealth Hawk antenna aiming questions:



As you can see the contour changes with various frequencies. The VHF is pretty well straight forward & backward <---->, whereas the UHF contour is more of a 4way [ X ] cross pattern.

I borrowed these charts from one of hol_ands 1st nec modeling results of the Stealth Hawk design to demonstrate how the antenna aiming relates to the contour of the Stealth Hawk antenna's gain patterns.

I'll try the extra cable idea first since that's pretty easy to test out. At the end of the day I might be able to live without the station since I'm picking up all the Cincy ones so well.

I suppose it's a testament to the Stealth Hawk that it's pulling in some of my locals too well!

loveota,

Go back to post#184 & post #190:

I have made a few mods to your test model that takes VHF & nikiml's top diamond optimization into consideration. I made the following leg length changes.

The top diamond leg length is changed to 6.5"
The bottom diamond leg length is changed to 8.5"
The bottom splayed leg is 15"
All side bends are 80° and the top bend is about 120°
The diamond height to the feed point is 9.5"
The width of the diamond is 12"

This seems to give a stable full range 7-51 with good signal strength performance throughout the VHF & UHF bands +FM.

This is what I have on my tower now. It seems to perform quite stable with good gain on all my regular channels. It's a combination of loveota & nikiml Stealth Hawk mods.

ota_canuck, today I built the stealth hawk in the post above. I had several inches of extra wire left over when I got to the bottom, so rather than cut it off, I bent them up on each side at a slight angle. Works great, works better than my double diamond stealth hawk.

How much extra material? I tried one like that with 5" wing tips, it was good for some VHF gain, but I found that cars and trucks passing by caused some flutter and pixelation. I cut the 5" off and the flutter problem was gone.

ota_canuck,

Today I built the newest revised version of September 10, 2010. I built it out of 14 gage copper wire. What gage of wire do you recomend for the build of this antenna. Is flat wire better than round wire, or does it make any difference.

I Spent most of the afternoon rotating and taking notes on the progress. I cannot get the Stealth Hawk to be able to receive no more than 11 stations out of the normal 14 stations for this area.

I beleive that part of the problem might be that the pole or mast is only 18.5 ft in lenght. I like the simplicity and the easy build of this antenna, but some how it is not working for me in comparison to the 9 1/2" Wiskers type .

Will use and play with the 14" long leg lenght antenna tomorrow. Will see if this one works much better than the 15" leg lenght one.

Will report tomorrow on the testing progress.

avenger

I like the Nec pattern but it shows some tilt should be needed, for the forward gain is pointing just below center. Vhf gain is just over 2dbi with @ 4 swr, Uhf showed 5+ dbi with swr of 2 across the band. The 5" extra legs messed up the swr. I played with the height if the bottom legs and found 8" below the feedpoint was a good compromise of gain and swr. Opening the top sends the gain pattern downwards and swr up.
Its interesting to see how the patterns change as you increase frequency . The higher ones is where I`m seeing the most of the omni-like patterns. This model should do well in scattered UHF markets aimed just right.

ota_canuck,

Today I built the newest revised version of September 10, 2010. I built it out of 14 gage copper wire. What gage of wire do you recomend for the build of this antenna. Is flat wire better than round wire, or does it make any difference.

I Spent most of the afternoon rotating and taking notes on the progress. I cannot get the Stealth Hawk to be able to receive no more than 11 stations out of the normal 14 stations for this area.

I beleive that part of the problem might be that the pole or mast is only 18.5 ft in lenght. I like the simplicity and the easy build of this antenna, but some how it is not working for me in comparison to the 9 1/2" Wiskers type .

Will use and play with the 14" long leg lenght antenna tomorrow. Will see if this one works much better than the 15" leg lenght one.

Will report tomorrow on the testing progress.

avenger

The SH must be mounted at the very tip of the mast. The mast can not be any higher than the feed point. The SH antenna performs very bi-directional/multi-directional and nearly omni-directional on some frequencies. It will work with VHF and UHF channels from 7-51. The SH is very sensitive to any objects being too close to the element. It must be mounted away from any nearby trees/walls/people etc. If anything is near the antenna, then it will not work well.

I still don't understand why it's not working for you

What are you using to separate the feed points? Plastic? Wood?
Is the mast metal, plastic ?
What kind of balun?
Are you using an amplifer or splitters?
Are you using RG6 cabling?
How long is the downlead cable?

I use #10 galvanized wire [about 1/8" thickness]. I have used flat aluminium material, but I find that round wire works slightly better. You could try thicker wire, but I have no reason to believe that #14 wire should be a problem. There is something amuck with the build or the mast mounting or the antenna location. You should be getting as good as what you can get with a 4bay, but a lot less aiming is required with a SH antenna.
Rotating the SH antenna in very slight increments can make the difference in being in a null or a lobe.

loveota,

That may indicate that the top diamond may be a bit too big for the leg lengths. I've seen the reverse of this in some earlier SH models where a 7" diamond configured over a 8" lower leg configuration tilts the gain upward.
_______________________

Maybe taking 1" away from the top diamond legs would shift the gain upwards:

- top diamond legs 6"
- bottom diamond legs 8"
- bottom legs 15"
_______________________

I still believe the the longer 14-15" lower legs are needed to achieve VHF. When I've tried shorter lower legs, the VHF drops off. I agree that the 8" lower leg length is ideal for the UHF gain&SWR, but it defeats the purpose of the Stealth Hawk's VHF/UHF multiband capability.

ota_canuck,

The antenna is at the tip of the mast.
Am using plastic to separate the feed point.
The mast is wood. 1"x1"x8'
Radio Shack balun.
No amplifier or splitter.
Using RG6 cabling.
Are you reffering to the total run of cable?. Downlead cable?

Noticed that rotating the antenna ever so slightly does change the amount of stations received. I keeps flactuating between 9, 10, 11 stations. Loosing stations channel numbers like 13, 32, 47. and then channels 19, 49, 54. Never repeats.

The antenna is doing and showing many stations, but not as much as the Bow Tie type. I am not disapponted with its performance, but after reading some of the comments and reviews, I though that it would out perform the Gray-Hoverman and the Bow Tie.

Will reverify all the point that you made such as being in the top most part of the mast and so on. Will give it another try tomorrow, will report the findings.
avenger

avenger, get a signal amplifier and mount the stealth hawk as high up as you can get it. If you go to a Home Depot or Lowes, they have 16 ft telescoping poles, which you can attach a squeegee to and wash windows high up. Attach the stealth hawk to it extend it to the maximum and then attach it to your mast with a couple of U bolts. Stealth hawks are so small and light weight that wind is rarely a problem.

ota_canuck, I hate to do it, but tomorrow I will cut the excess wire off the bottom legs of the stealth hawk. Also, from my personal experiences, I have found that thicker wire helps with reception of channels. It doesn't necessarily help pull in new channels, but the ones you get come in better. I especially noticed it with the stealth hawk I made out of 1" copper pipe.

Avenger,

The Stealth Hawk is not a high gain antenna, so if your cable lengths are 30ft or more, you would definately require some sort of amplification. A 4bay antenna would be a higher gain, but being a more directional antenna it would have a higher gain to be able to deal with longer cable lengths up to 50ft without needing an amplifier. I think in your case, some kind of amplification will be needed if you intend to use the multi-directional SH antennas.

Holding an antenna in the air on a wooden stick won't get very consistent or stable results. An antenna must be mounted secure and steady to avoid any irratic movements. Rocking or shaking an antenna back and forth will cause pixelation and dropouts due to the induced multpath effect of the signals. Ideal height for antenna mounting would be 20ft+ or at least over the rooftop of your house to avoid reflected multipath issues.

I have always used a metal mast grounded properly. Antenna mast grounding is quite important for both safety and performance. If you're in a location where multipath is a local issue, then you'll have to stick with some of the more directional antennas like the XG91 with a good f/b ratio and using a rotor to aim at each transmitter to tune in specific channels.

ota_canuck is the man! I cut the bottom legs off and it made a huge difference in the number of channels I pulled in.