|Topic Review (Newest First)|
|2020-01-24 07:55 PM|
Thank you for the photo; that looks promising. Can you remove the small tree?
|2020-01-24 02:40 PM|
Years ago I did use a Directv dish here, but when they upgraded their equipment to use SWM that ended. Currently using an RCA preamp on the antenna, I started out with a CM 7777 but the power supply would get extremely hot and the RCA works just as well as the CM did.
The bowtie I've settled on is the holl_ands New UHF concept with the dimensions tweaked for max gain at my UHF frequencies of interest. At 16 dbi and a bit over I'm probably as good as it gets for a 4 Bay. Once this is in place I'll be playing with a Udi-Yagi for the VHF.
Thought you might like to see the 'ditch' I have to aim up through. The desirable direction is basically through the smaller tree at the end. Couldn't seem to get it to load vertical in my album though.
|2020-01-24 01:15 PM|
It would help if you could get your antenna above the trees on a tower or mast when aimed at Augusta, but that might be difficult.
Some people with a similar location have found improvement with a high gain Yagi like the Antennas Direct 91XG or the Solid Signal HDB91X and a preamp, but I'm not certain it would help you. You are using a preamp now, aren't you?
You can click on Map for a channel in your report to see the coverage map. If you click on Transmitter Distance for a channel, it will show the terrain profile.
|2020-01-24 01:13 PM|
IMO, as long as you don't have any interfering signals or noise from the rear, I would concentrate on maximizing gain (and return loss) at the frequencies of interest.
|2020-01-24 11:42 AM|
|orbot||You should be able to improve the F/B and F/R values by using a smaller grid spacing on your reflector. That also may increase gain a bit, but also swr, so you might want to move the 4-bay further away from the reflector if swr is "too high". The gain values in those pictures seem kind of high for a 4-bay, did you run the Average Gain Test before calculating the results?|
|2020-01-24 11:15 AM|
|ExDilbert||One thing the posted map doesn't appear to take into consideration is signal refraction. That could explain what is being observed. I can get a couple of channels several miles behind a hill due to refraction. It shows up on the channel coverage maps on TVFool.|
|2020-01-24 10:29 AM|
Thank you for the information,
The reception maps pretty much agree with real life, I can get Virtual channels 6 and 54 pretty good (even with the Hoverman I have up now). Used to get Virtual 26 too but ever since that station was bought by Spectrum they reduced power. Found it interesting that moving my antenna about 15 ft I can get 26 but 54 drops out.... move it back and 54 comes back and 26 drops out... still fishing for the sweet spot in this confined area.
My bad about Real channel 31, should be 36 so I'll have to do some more tweaking to broaden the peak gain to cover 569 through 604 MHz.
Cable available... that's funny, lucky to have power at the end of a power line. Only cellular service that's close to dependable is Verizon and that can be spotty.
I do find that these forecast reception maps can be a bit pessimistic about the stations you may be a able to get.
Would like to ask if you could comment regarding the F/B F/R projections and if these values affect the gain?
A big thank you for all the wisdom you have shared!
|2020-01-23 10:01 PM|
|2020-01-23 08:10 PM|
It is the real channel number (also called physical channel or RF channel) that determines what antenna is needed.
VHF-Low, real channels 2-6
VHF-High, real channels 7-13
UHF, real channels 14-51
The virtual channel number (like 5.1 or 5-1) is a holdover from the analog TV days to maintain the identity of the station, and is what the TV displays. By convention, the virtual channel number is given in the decimal form to keep it from being confused with the real channel number.
569: is real RF channel 30, WAGT ?
575: is real RF channel 31, ?
Virtual 6.1 is WJBF ABC, real 42, moving to 28 during Repack phase 8 1/18/2020 to 3/13/2020
Virtual 54.1 is WFXG Fox, real 36, staying there
Virtual 26.1 is WAGT NBC/CW, staying on real 30
Virtual 12.1 is WRDW CBS, staying on real 12; you will need a very good separate VHF-High antenna
Siting the antenna
scroll down to Trees and UHF
Umm, do you have cable in your area?
|2020-01-23 04:48 PM|
Oh my, you were so right... I hadn't checked the impedance setting, with it set to 300 it looks much better!
|2020-01-23 02:23 PM|
I was wondering about the affect of the nasty looking F/B F/R curve, any recommended cures? I attached the rabbitears info just to add a little humor to your day (I guess it'll work by pasting the link in?). All three frequencies of interest are at 300 ohms, sorry about the overlay there. The channels I can get most of the time are virtual 6 and 54 and I'm trying to add 26 which I can get when there's a low cloud ceiling. I can also get channel 12 but conditions have to be right. Very constrained on mounting location/height and by dense 100+ ft trees from 95 deg to 225 deg and another stand of trees from 270 deg over to about 70 deg. I've tried several time for the stations at ~ 222 deg but guess I can't get past the edge of trees that are blocking that direction.
|2020-01-22 06:33 PM|
Thank you for the images.
Your SWR of 6 is too high. It will cut your Raw Gain figure way down for less Net Gain.
Your previous post stated 300 ohms, but you have the ohms in the SWR curve window covered by a 540 MHz label. Did you set it for 50 ohms instead of 300 ohms?
Your design looks like a modification of holl_ands NEW-UHF [470-608 MHz] Free-Form 4-Bay (NU-FF4) Bowtie Antennas with Flat Screen Grid Reflector:
What are your whisker lengths?
I would still like to see a signal report.
What are the callsigns?
|2020-01-22 02:14 PM|
Thanks for the information. Constructive/instructive comments appreciated since I'm still learning. Created an album and uploaded pictures, now I'll try to add them...
|2020-01-21 04:23 PM|
You can make a forum photo album and post from that. The width is limited to 600 pixels. You can also use an image host like imgur.com and link from that.
How to create a photo album for use on the Digital Forum
|2020-01-21 02:19 PM|
|paxplant||Well I've messed with this long enough an have to push the button to start building. Getting ready for a repack scheduled for February. I may come back later and add a separate VHF, but for now this is the best I've been able to do with a simple 4 Bay bowtie with a flat screen grid tweaked for 557, 569, and 575 MHz. Gain of 16, impedance ~ 300, SWR ~ 6 at all three frequencies. I have the screen shots to post but I don't know what's involved in setting up a URL for them. For a 36 x 42 size it'll work out for me.|
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