: Stacking, Ganging, Combining TV Antennas
I currently have two cm4221's combined pointing in two directions about 85 degrees apart. They are on the same mast, one on top of the other. My lower antenna pointed to the closer broadcast tower. I want to move the lower antenna higher for better reception. I'm making a bracket, and was wondering if I may see less multipath if I install the two antennas in a t shape shielding the side of the one pointed at Buffalo, behind the reflector of the one aimed at Toronto. Or is it best to have them in an L shape like those 4228 knockoff's that have a hinge in the middle.
2011-09-23, 07:49 PM
If i can make a different suggestion, before you get carried away with moving or bracket making, try reducing the angle between them. Making the separation angle between them reduces multipath and they add together better. Most of the toronto stations are now a lot higher power than before. All toronto except Sun are now a lot easier to get.
I would point the buffalo antenna at NBC and the toronto antenna about 30-35 degrees east of that
2011-09-24, 11:48 PM
I live in East York & I want to combine 3 separate uhf antennas aiming in 3 different directions to avoid using an antenna rotator.
I have two Antennacraft U-8000's and one original Channel master 4221.
I have a 35' tower & a 10' mast. I want to aim one 8 bay U-8000 at Rochester, the other 8 bay at Erie Pa, and the 4 bay 4221 at Buffalo.
I have a Lindsay 3 way splitter with 6.8 db per tap that I will use to combine the three antennas. I will place one 8 bay at the top of the 10' mast the other 8 bay around half way down the mast & the 4 bay on the tower leg in order to separate the 3 antennas to prevent them from interfering with each other. I will feed the combined signal into a Channel master 7775 uhf preamp and I'm using Belden 1694A rg-6 coax as my feed.
Can anyone offer any further advise on my soon to be setup ?
2011-09-25, 09:15 AM
Two bits of advice for you, Bruce.
1) Don't fall off the tower.
2) Don't be surprised if it doesn't work the way you want it to.
2011-09-25, 09:46 AM
Bruce Rochester has 2 VHF stations. So I would not expect the U-8000 to get them. Also heed the advice of ProjectSHO89 #2. It may just be a frustrating effort and you will be up/down the tower repeatedly, hence advice #1. Make a spread sheet to document direction and results so you don’t get muddled. Have U got a tvfool report we can look at?
2011-09-25, 01:01 PM
I will be careful & I have been climbing tv towers since I was a kid
so the height does not bother me.
I'm using a cm4221hd aiming half way between Buffalo & Rochester & a cm4228hd aiming towards Hamilton right now. I have two separate coax cables
and use a switch indoors to switch between the two antennas.
I pick up all the Buffalo stations 90% of the time and Rochester 8.1 8.2 - 13.1 13.2 - 21.1 21.2 21.3 - 31.1 31.2 as well as 3.1 3.2 from Saracuse the odd time with the 4 bay. I pick up 24.1 54.1 54.2 54.3 from Erie Pa off and on as well as 67.1 67.2 67.3 67.4 from Buffalo once in a while & I'm not aiming at it.
I just tired of using a rotator so this is why I want to try the three antenna setup. Back in the analog days it would never work due to ghosting but I figure with digital, the tv will just show the station from whichever antenna it Picks it up from.
Who knows, maybe I'd be better off with one of those stupid flying saucer
antennas with a big preamp and just do the omni directional thing, lol.
I will let you guys know how it works out.
2011-10-05, 07:20 AM
I have an RCA ANT751 antenna outside in London Ont. about 10 ft above ground and am able to pickup CKCO 13.1 Kitchener with about 80% strenght on sunny days but when it rains I lose the signal, anyway to stabalize signal during rainy days?
Also would love to pickup Global 6.1 Paris, but nothing so far, any suggestions how I might be able?
The high UHF channels are giving me a bit of problems CHCH 51.1 Almost never a signal and 69.1 not stable. I am thinking of buying the CM4221HD Antenna, what woujd be the best way to join the RCA ANT751 and CM4221HD antennas together?
2011-10-05, 09:56 AM
Before worrying about stacking/ganging antennas, I'd try all single antenna options first. Not sure on the stats on the ANT751 but there should be antennas with higher gain out there for deep fringe.
Why not post your TV-fool so we can have a look at it and hopefully be able to help?
2011-10-05, 10:10 AM
I recently combined a Kross UHF/VHF to my existing Digiwav UHF antenna. They are separately masted horizontally in an upstairs bedroom, approximately 5 feet apart mast to mast. After the digital conversion I realized that I needed a VHF component to properly receive CFTO from my location in Oshawa. Previously I had to point the UHF Digiwav directly at the CN Tower to receive CFTO. Otherwise it would scan but was unwatchable. However, this adversely affected reception from Buffalo transmitters. Hense the second Kross antenna with a VHF component. The Kross is pointed south, directly at Buffalo, while the Digiwav is pointed south-west.
The plan worked. CFTO is now rock-solid and a number of other stations have improved, namely the Buffalo stations. All except FOX-29 which seems to have experienced some minor signal degredation but is still watchable.
However, while the plan worked, other possibilities did not materialize, namely CHCH (gone forever I guess), CTV-TWO (which would have been nice), and that WBBZ (an interesting curiousity).
I recently acquired 2 DB8s and had planned on keeping just one but decided to experiment with stacking them because we have our antenna in the attic. There is lots of head room in the attic so there was no problem with the height. I installed them so that the distance between the bow ties on the 2 antennas was the same as the distance between the bow ties on each antenna. There was a noticeable increase in the strength of signals from most channels and we also picked up some more channels. Overall I am quite happy with the results.
2011-10-25, 11:52 PM
I used to love my DB8 when I had it. I ended putting it up at my dad's.
For serious Dxing the beam width was killing me with Co channel so i replaced it with a XG91.
2011-10-26, 05:32 AM
I installed them so that the distance between the bow ties on the 2 antennas was the same as the distance between the bow ties on each antenna..
with the CM4228's (a similar antenna), some have used double this distance as the spacing
2011-11-10, 10:44 AM
I am the recent owner of an Antenna Direct DB8 and I am very satisfied.
I am in a deep fringe area. My current installation picks up quite a few stations from 65 miles away, along with the local stuff. Some of my digital signals from the distant stations are poor at times (even with a rotor and amps.), and I'm looking to improve my signal quality, especially in the UHF band. I was thinking of going with two antennas (two DB8) stacked (ganging). I'm looking for information on the signal gain increase by stacking two coupled antennas aimed at the same direction. Are there any specifications on how far they should be spaced apart vertically for optimum performance? Any special signal splitter coupling needs between antennas? Is there a specific brand and model of splitter coupling required? So far, the only thing I know is the cables between the antennas and the splitter coupling have to be the same length. I will fix an amplifier right after the splitter.
2011-11-10, 11:00 AM
2011-11-10, 12:28 PM
If you could find a method of combining the output of each antenna with no loss, you would hope to see gain increase by 3 dB. Perfect and lossless don't exist in this context. If you do an excellent job, 2 dB gain will be worth a hearty pat on the back.
In addition to old sparks excellent links: http://www.anarc.org/wtfda/stagger.pdf
Bill Thompson talks about several concepts including 1/4 wave transformer built using 450 ohm twin-lead. The benefit is low loss, the negative is that the antenna array becomes a narrow band antenna, optimized for only one channel.
2011-11-10, 02:09 PM
Here's what I would suggest trying.
Arrange your two DB8s as shown in the 16bay link. Remove the harness from both DB8 antennas.
Run 300 ohm twin lead from the 4 bay antenna on top of the left hand side of the stack to the 4 bay antenna on the bottom of the left hand side of the stack.
Do the same on the right-hand side between the top and bottom 4 bay antennas.
Make your own 150 ohm open line to run between the two runs of 300 ohm twin lead. Feed at the mid-point with 75 ohm coax. Wrap the coax around some ferrite to make a current balun.
Check out: http://www.zen70432.zen.co.uk/EME/EME_Array1.html
3rd and 4th photo down for an idea of what I'm clumsily trying to describe. Better yet, read:
2011-11-14, 10:04 PM
Has anyone tried a triple stack of 4221HD's.
I have some problems with my double stack of 4221HD's with some Buffalo channels (2.1/subs is not consistent, Fox (14.1) is tropo only, as is 49.1).
I have posted my reception results in the Hamilton/Stoney Creek/Brantford thread.
I'm wondering if the increased gain is worth the narrowing of beamwidth (as I use 2 stacked 4221HD pointed between Buffalo and TO, or if there are other problems to contend with.
2011-11-14, 10:39 PM
I believe the ratio is 1:1 narrowing the beam width and providing additional gain. In other words. If a certain antenna has 10 dB gain and a 40 deg beamwidth at a given frequency, two of those antennas stacked perfectly would have 13 dB gain and a 20 deg beamwidth at the same frequency.
You're kind of in a tough spot because you need a fair bit of gain to pull in buffalo stations reliably, but narrowing the beamwidth means you'll have to aim more directly at buffalo. There should be a sweet spot where you can aim slightly more towards buffalo vs. toronto, and a sweetspot of gain/beamwidth where you can pick up the most channels reliably. After that point you'll have to go with a rotor or a switch, or use a dual tuner setup.
Off topic: I used a dual tuner card HTPC in grimsby with one tuner card dedicated to Toronto, and one for Buffalo. Worked great! Individual amps for each tuner, separate cable runs, etc. etc. etc. :D
2011-11-19, 11:14 AM
I know your supposed to mount UHF above VHF but for my situation I only have 2 UHF channels to tune in both located in the same direction and the VHF stuff I get is more scattered and weaker therefore I want to keep my VHF up high and be able to use my rotator.. so I have my vhf probably 10+ feet above my UHF 8 bay.
now the problem I'm having is with both antennas hooked up I lose my PBS 10-1. I'm only using a common splitter to combine the signals but All my channels are working except that one.
IF I remove the splitter and just use my VHF antenna I get the channel back. so can I assume that the antennas will be ok mounted like this or is it possible it could only cause interference when they are both hooked up?
Right now both antennas feed into a common splitter in reverse then into a cheap ebay +10db amp. I'm hoping to ditch that junk and replace with a channel master titan 7777 amp with the separate VHF and UHF inputs or even just a proper VHF/UHF combiner then maybe I'll get my PBS back..?
OR is it more likely interference from the way I've mounted my antennas?
2011-11-19, 12:17 PM
I'm only using a common splitter to combine the signals but All my channels are working except that one.
That's your problem. You already know the solution....