After doing much research, I have decided on two different antennas of the same breed.

Since my 12ft 2inch aluminum mast might not have enough real state to have two of these 8bay bowtie UHF antennas mounted on top of one another, AND since they will be pointing in two different directions anyways, I thought I might mount the two back to back facing in exact opposite directions.

I will benifit in two ways from this. I can get two high performing antennas that work different areas of the UHF band complementing one another and I also won't have to turn the rotor as much.
My only concern is will mounting these two antennas back to back have a negative impact on one another?

Below is the two antennas to be used.

ant1- Channel Master CM 4228 8-Bay Bowtie UHF Antenna. This antenna has good gain in VHF-hi, and better gain above channel 30 to 50 than ant2 (39.5 inches wide, 35 inches high) facing west

ant2- Winegard HD 8800 8-Bay UHF Antenna This antenna has twice the gain as ant1 on channel 14 , and better gain up to channel 30 where ant2 is lacking. (45 inches wide, 34 inches high) to be facing east

Both antennas will have cm 7777 preamps. Ant 1 will use the existing 7777 preamp with vhf/uhf amp and RG-11 like coax. Ant2 will use the 7777 amp with uhf only and RG-6 , or RG-11.

Since both antennas are pointed in opposite directions but screens are a different size, will the mounting of them back to back have a negative affect on gain, or change the bandwidth ? If I can pull this off, it will solve many issues as ant1 will deal with stations that favor it's band coverage (vhf-hi, UHF above ch 30) and ant 2 will cover between 14-30 which is the direction all those stations are.

If your eyes haven't glossed over by now, I could use some advise since mounting 70ft in the air is a one shot deal. I can't afford to pay someone twice.
Tnx guys.
..HM

Just another thought, since the continuous screen on the CM-4228 ant is actually using it
as a primary radiating element giving it high gain on VHF, won't this give the Winegard a similar effect since behind it's screen will be the channelmaster one? This might be unwanted if it changes the slope of the gain on UHF.

What you need to do is run both antennas into a coupler that has plenty of isolation bewteen the two ports. This is no problem at all for 50Ω systems (http://minicircuits.com/products/psc_coax_2_0.html), but I'm having no end of grief trying to find the equivalent for 75Ω operation. :(

A coupler so I can combine the two? I'm pretty sure I will just switch between the two. Its not really an issue to have both active at one time. One trick I used to do with another setup was to just switch the power off on the preamp I wasn't using and that worked great.

I'm more worried about the presence of the other antenna almost touching the back of the other somehow altering the DB gain curve. I really like where the gain is on both antennas and wouldn't want that to change.

it is really best to use an A-B switch for two "same frequency" antennas pointing in different directions. If you join or couple them, they can interfer with each other resulting in a 3db loss of signal. Channel Master makes a "join-tenna" coupler which works for specific channels, but needs to be custom made and is now hard to find. The other antenna, is not coupled to the first, should just act as an additional reflector behind the active antenna.

You'll get an interaction between the two.I wouldn't do it.Go ahead and put the 5ft dish on top,then put a 10 element highbander under that.You got about 7ft down to the Log mount to work with.The rotor you have is certainly up to the task,and I assume the 2 inch aluminum mast is 1/4 inch wall,so no problem there either.Do you know what the tower is specd for as far as windload? What size guy wires? The dish and the highbander should only be around 6 sq. ft. max. Not sure what your Log is.

iChannel Master makes a "join-tenna" coupler which works for specific channels, but needs to be custom made and is now hard to find. The other antenna, is not coupled to the first, should just act as an additional reflector behind the active antenna.

Yes, I read about that join-tenna. Sounds like just the ticket if you only had one channel in another direction you needed to receive. Basically it just eliminates having to turn the antenna under that condition.

You'll get an interaction between the two.I wouldn't do it.
Thats what I was wondering after reading about the CM-4228 UHF Bowtie and how the continuous screen affected the gain in different bands. I was hoping if it did interact, it would be in a positive way.


Go ahead and put the 5ft dish on top,then put a 10 element highbander under that.You got about 7ft down to the Log mount to work with.
unfortunately, I don't think I will get away with it. You see, the log is mounted vertical, so the end reflector is pointing skyward about 5 feet.
I think I will only have enough room for one antenna above the log, and since that bowtie seems to have gain in the areas that will benefit me the most, I might have to just go with that.

I wish these ant mfg would hurry up and cut some antennas for ch 7-60. I know terrestrial digital has one in he works but it will be months. All the other antennas I looked at seem to be great performers above channel 50, which serves me and most of the digital world no good.



The rotor you have is certainly up to the task,and I assume the 2 inch aluminum mast is 1/4 inch wall,so no problem there either.Do you know what the tower is specd for as far as windload? What size guy wires? The dish and the highbander should only be around 6 sq. ft. max. Not sure what your Log is.
I have no guy wires. It a self support Xbrace style delhi MD with 6sq ft of windloading. You are correct about the mast size Max HD.

Thats what I was wondering after reading about the CM-4228 UHF Bowtie and how the continuous screen affected the gain in different bands. I was hoping if it did interact, it would be in a positive way.

unfortunately, I don't think I will get away with it. You see, the log is mounted vertical, so the end reflector is pointing skyward about 5 feet.
I think I will only have enough room for one antenna above the log, and since that bowtie seems to have gain in the areas that will benefit me the most, I might have to just go with that.

I wish these ant mfg would hurry up and cut some antennas for ch 7-60. I know terrestrial digital has one in he works but it will be months. All the other antennas I looked at seem to be great performers above channel 50, which serves me and most of the digital world no good.


I have no guy wires. It a self support Xbrace style delhi MD with 6sq ft of windloading. You are correct about the mast size Max HD.


Ok, you can still put two above the Log.An XG91 and a highbander.About 2sq. ft. total windload.Seperation between mounts at 32 inches is ok.With this you'd have more of a spread than using an 8-bay.

Winegard has some UHF/highbands out now,but the above would work better.

Ok, you can still put two above the Log.An XG91 and a highbander.About 2sq. ft. total windload.Seperation between mounts at 32 inches is ok.With this you'd have more of a spread than using an 8-bay.

Winegard has some UHF/highbands out now,but the above would work better.
Hmm, I looked at the X91, and you are right, it probably would fit nice. I was all excited till I went to HDTV Primer site and looked at the "net gain" for that antenna. Correct me if I'm wrong, but I think it peaks around ch68 and performs worse than the bowtie between ch 20-50, even though it has incredible gain, sadly its in the wrong area. This is the same problem I have with my 5 ft CM dish. It apparently tops out at 21db gain, but its up on ch 83 lol.

Check it out and see what you think.
http://www.hdtvprimer.com/ANTENNAS/comparing.html

Thanks Max HD

Thats why I got the idea of the second bowtie back to back as if you look at antennas "A" and "E", they complement each other so well.
I'll take a look at some of the winegard highbanders. I really only need to receive channel 7 at about 48 miles max.