Dual UHF Antennas?

[Sonnie Parker]

Is it possible to take two UHF antennas mounted together and combine the signal into one cable for reception of OTA digitals where the towers are located in opposite directions?

I don't want to have to rotate the antenna everytime I change to a certain local channel and an omnidirectional will not pick up a couple of my OTA channels.

[Mark Lamutt]

The answer is maybe. Usually you'll have to use filters to filter out the channels that you don't want to receive on each antenna because both antennas are receiving at least some signal from all of the channels, even if the signals are coming from different directions. The two different signals from the same channels interfere with each other.

You can install a rotor on your antenna mast to automatically rotate your antenna for you, or you could put the 2 antennas on an A-B switch and then use the switch to control which antennna you are using for each channel.

[Sonnie Parker]

I have a rotor now but I was just thinkin' it would be nice to not have to rotate the antenna at all if there was a simple solution.

What kind of filters am I lookin' for?

[Mark Lamutt]

From what I understand, the filters are expensive and not easy to find.

Something like these I think (this is the first time I've ever tried to do any research on it): http://web1.triax.dk/ifs/files/triax/is/presentation/home/Satellite_x_terrestrial/dth_(direct_to_home)/maste_elektronik/filters_and_combiners/channel/channel.jsp

[Sonnie Parker]

Is there anything to this: (20db isolation?)



2-Way Joiner/Splitter
UHF/VHF/FM
Model # 0538 2-WAY JOINER USED TO COMBINE ANY 2 (54-900MHz) TV ANTENNA SIGNALS AND COME DOWN ON ONE WIRE $7.36 (75 Ohm) High-quality ferrite hybrid splitter circuit gives lowest loss and excellent isolation. One port DC pass permits use with a preamplifier.
Input 1 54-900 MHz Loss 3.5 dB
Input 2 54-900 MHz Loss 3.5 dB
Isolation 20 dB

[Mike123abc]

I have played with filters in the VHF band and have to say they open up their own set of problems. A better solution may be channel cut UHF antennas. They are cut to only pick up a small range of channels (usually a range of 5 or so). So, if the channel numbers are not adjacent, you could get 2 cut antennas and then combine them.

[jimisham]

Is there anything to this: (20db isolation?)



2-Way Joiner/Splitter
UHF/VHF/FM
Model # 0538 2-WAY JOINER USED TO COMBINE ANY 2 (54-900MHz) TV ANTENNA SIGNALS AND COME DOWN ON ONE WIRE $7.36 (75 Ohm) High-quality ferrite hybrid splitter circuit gives lowest loss and excellent isolation. One port DC pass permits use with a preamplifier.
Input 1 54-900 MHz Loss 3.5 dB
Input 2 54-900 MHz Loss 3.5 dB
Isolation 20 dB

That should work IF one antenna is a VHF and other one is a UHF but if you try to use 2 of the same kind you're probably going to experience ghosting and other interference.

[DBSPaul]

For your situation, you would be looking for a high-pass filter for one UHF antenna, and a low-pass filter for the other antenna, and then you would combine the filter outputs. Depending on how close the channels are to each other in frequency, it could be somewhat tricky setting the frequency points for each filter. I agree that channel cut UHF antennas would be the best solution, however I've never gone looking for those.

[dishrich]

Sorry guys, but using cut to channel antennas isn't going to work that good. If you get decent reception with a standard antenna, a cut to channel antenna is only going to attenuate some of the "other" channels you want to reject. Also, cut to channel antennas are NOT exactly cheap, either.

Mark's idea of the A-B switch makes the most sense for your situation. I have done this here many times, since we can pull the off air channels in from Peoria, where they all come from the north, while our locals all come from the east. Economically, it's almost a wash compared to the cost of a rotor & wiring, plus it's much fast to flip a switch, then wait for a turning antenna. Also, if you have multiple TV's in the house, all sets could be set up to switch between 2 antennas. (thought this would obviously involve more wiring for each one) But, if you're using a rotor, then all the sets could only watch from that same direction.

[Sonnie Parker]

This is what we have right now:

Currently we have a remote controlled rotor, a Channel Master antenna (not sure of model but it's not deep fringe-maybe a fringe), and a Channel Master 7777 Titan 2 amp (26db gain UHF). We are up on a hill top with clear line of sight to most all towers.

ABC is our only digital station as of today and we can get it fairly good on VHF although it is the weakest station. I can not receive it on the 6000... it flashes 50-55% signal strength.

Below is an image of the 4 network tower locations and distance from me.

http://www.snapbug.ws/images/towers.jpg

I think I'm gonna need a bigger UHF antenna to get ABC 51.

[dishrich]

If you really want that distant station, I would suggest going with something like this, plus maybe a preamp:

If you want a UHF only antenna:
http://www.winegard.com/offair/pdf/pr-9032.pdf

If you want a deep fringe V/U ant:
http://www.winegard.com/offair/pdf/pr-7052.pdf

If you're looking for something a little fancier:
http://www.winegard.com/offair/pdf/hd8200p.pdf
This is Winegard's top of the line V/Y ant...

[DVDDAD]

Sorry guys, but using cut to channel antennas isn't going to work that good. If you get decent reception with a standard antenna, a cut to channel antenna is only going to attenuate some of the "other" channels you want to reject. Also, cut to channel antennas are NOT exactly cheap, either.

Mark's idea of the A-B switch makes the most sense for your situation. I have done this here many times, since we can pull the off air channels in from Peoria, where they all come from the north, while our locals all come from the east. I thought I'd jump in and give you my 2 cents... At 50-55 miles a cut to channel antenna might be the difference in receiving an acceptable signal while combining two antennas. It was the only way I was finally able to pull in a week signal and get good results while combining two antennas. Yes, the cut to channel antennas aren't cheap; mine cost me about $175, but I felt it was worth it in order to pull in Monday Night Football and not have to use a rotor. As far as an A-B switch is concerned, it may also be a good solution if the signals from the two antennas interfered with each other and the filters either didn't provide acceptable results or were too costly. Try RadioShack's remote controlled A-B switch if you don't want to have to get up and flick the switch.

Sonnie, I must say that from Mark's initial reply to your post throughout this thread you have received some great advice and some options and I'm sure with some tinkering you'll get the solution you were looking for. Good luck!

[Sonnie Parker]

I agree Adam... good info to work with.

It appears that the UHF only antennas will have better reception capabilities than a combined antenna.

Maybe a super strong UHF only to reach out and get channel 51 would grab 14 and 16 since they are the strongest and closest signals. Then rotate to 55 when CBS is needed....which is quite a bit.

Reading my manual on the rotor remote I can program in channels. It moves fairly quick when I was testing it earlier and it would have far to move from 51 to 55. This would eliminate an A/B switch.

I really wouldn't need a VHF antenna.

Is the Winegard 9032 the strongest UHF antenna available? Can it be amplified with the Channel Master 7777?

Thanks guys! I really appreciate your help.

[DBSPaul]

Okay, with more detailed info it's now a lot easier to address your situation. Obviously you want a VHF antenna aimed at channels 14 and 16. 51 and 55 are fairly close to each other (frequency-wise), so a 6-pole Chebychev filter may not be completely out of passband (in other words, there would be some signal overlap between the high-pass and low-pass filters) which your amp is going to worsen.

Also, filters have an insertion loss (as well as combiners), so if you're dealing with a weak signal to start with, unless you increase your originating signal strength you're just going to make a weak signal worse. So this would definitely point toward getting a good, high-gain UHF-only antenna.

As for the CM 7777, I've got that exact amp and am running seperate VHF and UHF antennas into it (along with sets of filters for each .. LONG story), so yes it will work with basically any antenna, VHF or UHF.

[Sonnie Parker]

Obviously you want a VHF antenna aimed at channels 14 and 16.Am I confused... I thought 14 and 16 were UHF not VHF.

Looks like the CM 4228 bow antenna is going to be the strongest UHF only antenna I can find. I believe I can install it above my original VHF/UHF antenna, disconnect my original UHF from the combiner and connect the new UHF or if I can get a better signal I will run a separate cable.

I'd like to keep my VHF though. As I understand it the digital UHF channels may well transfer back to VHF at some point in time to save power.

[dishrich]

Am I confused... I thought 14 and 16 were UHF not VHF.

They ARE - ALWAYS have been...

Looks like the CM 4228 bow antenna is going to be the strongest UHF only antenna I can find.

Hardly, THIS is MUCH bigger & better than that:

http://www.winegard.com/offair/pdf/hd9095p.pdf

I believe I can install it above my original VHF/UHF antenna, disconnect my original UHF from the combiner and connect the new UHF.

How are you going to "decouple" the UHF section from your V/U combo to do this???
I don't think this is going to work, unless you plan on going UHF only.

[Sonnie Parker]

Yep, the Winegard 9095 has better gain and beamwidth than the CM 4228. Thanks for the reference... I missed it somehow.

I noticed the "Front to Back" ratio is lower on the Winegard. Is this good or bad (not understanding F/B)?


How are you going to "decouple" the UHF section from your V/U combo to do this???
I don't think this is going to work, unless you plan on going UHF only.
I am thinkin' there are two wires coming into the coupler or amp... seems like I remember two wires at the antenna... one for VHF and one for UHF that have can be disconnected. BUT, and a BIG BUT, I could be wrong. I plan to visit the antenna in the morning to find out what I have up there. It's been 4 years and I just can't remember and didn't keep anything on the antenna that I can find.

[DBSPaul]

They ARE - ALWAYS have been...

Whoops. Brain fart.. It's been a few years since I did my antenna setup. The frequency lists obviously fell out of my brain's long-term storage.

How are you going to "decouple" the UHF section from your V/U combo to do this???
I don't think this is going to work, unless you plan on going UHF only.

Actually, if he sets the CM 7777 preamp to separate VHF and UHF inputs, then the preamp's filters will take out the UHF component of his V/U combo antenna. He would then just run another wire to the 7777 from the new UHF antenna.

[Sonnie Parker]

I think that's what I was thinkin' DBSPaul. Via the amp but I couldn't remember.


I did a search on F/B ratings and found that this will indicate how well the antenna rejects signals from the rear (and some more stuff too but really sounded irrelevant in my situation). I don't believe I'll have to worry to much about signal from the rear as they are well over 100 miles from me.

[Sonnie Parker]

Hmmmm... just found this test, although performed in 2001 it is still interesting.


Test Results - 4221, 4228, 4248, 4251, 3017, 9095, 8800

Results Definition:

XX-XX = Measured signal strength level

0-XX-XX = Signal locks on briefly but keeps dropping out

0-50 = Signal was detected but not able to lock

N/A = No signal detected



Note: Signal level refers to the Dish 6000 indicator which measures the signal quality based on percentage of errors. As long as the indicator stays above 48-50%, the signal will lock. I assume that if you have over 50% errors, the Dish 6000 does not have enough good signal to decode properly. A reading of 100% would indicate no errors in signal. I have found that at 47% I will see pixelation in the picture and below 46% the picture will drop out completely. Date: 04/24/01

Updated list with the addition of the 4228 and 4221. I was very disappointed by the performance of these antennas in severe multipath. I was hoping to get better reception and more channels, but the 4228 could not even get KNBC. The 4221 could not get any local channels. I only re-tested the 4228, 4221, 4248. I tested them all within 1 hour and on three seperate days, with and without amp. Results were always the same. Without amp, signal strength is less, with more drop outs.



**************************************************
****Channel Master 4248 (Long Range Yagi) With CM-7775 Pre-amp

MT. WILSON, LOS ANGELES, DIST= 15.5 MILES

KTLA 31...62-63, solid signal, no dropouts
KCOP 32...N/A
KNBC 36...58-59, decent signal, some dropouts
KCAL 43...N/A
KABC 53...0-50
KCET 59...0-50
KCBS 60...0-49-57, can lock in on good days with antenna angled 10 degrees up?
KTTV 65...0-50

MT. SOLEDAD, SAN DIEGO, DIST= 113 MILES

KGTV 25...74-79, very strong signal
KFMB 55...65-72, strong signal



**************************************************
****Channel Master 4228 (8-Bay Bowtie) With CM-7775 Pre-amp

MT. WILSON, LOS ANGELES, DIST= 15.5 MILES

KTLA 31...52-53, steady signal, but lower power
KCOP 32...N/A
KNBC 36...0-50
KCAL 43...N/A
KABC 53...0-50
KCET 59...N/A
KCBS 60...0-50
KTTV 65...0-50

MT. SOLEDAD, SAN DIEGO, DIST= 113 MILES

KGTV 25...69-76, steady signal
KFMB 55...68-72, fairly steady signal, some drop outs



**************************************************
****Channel Master 4221 (4-Bay Bowtie) With CM-7775 Pre-amp

MT. WILSON, LOS ANGELES, DIST= 15.5 MILES

KTLA 31...0-50
KCOP 32...N/A
KNBC 36...0-50
KCAL 43...N/A
KABC 53...0-50
KCET 59...N/A
KCBS 60...0-50
KTTV 65...0-50

MT. SOLEDAD, SAN DIEGO, DIST= 113 MILES

KGTV 25...85-87, strong signal, even gets 64-68 without amp?
KFMB 55...64-68, fluctuating signal, drops out when veiwing



**************************************************
****Winegard 9095 (Long Range Yagi) With CM-7775 Pre-amp

MT. WILSON, LOS ANGELES, DIST= 15.5 MILES

KTLA 31...48-51, steady signal, marginal strength
KCOP 32...N/A
KNBC 36...46-60, no lock, rapid fluctuations
KCAL 43...N/A
KABC 53...N/A
KCET 59...N/A
KCBS 60...0-50
KTTV 65...0-50

MT. SOLEDAD, SAN DIEGO, DIST= 113 MILES

KGTV 25...68-71, very steady signal, no dropouts
KFMB 55...48-54, locks in, but drops out 3-4 times a minute



**************************************************
****Winegard 8800 (8-Bay Bowtie) With CM-7775 Pre-amp

MT. WILSON, LOS ANGELES, DIST= 15.5 MILES

KTLA 31...0-50
KCOP 32...N/A
KNBC 36...0-50
KCAL 43...N/A
KABC 53...0-50
KCET 59...0-50
KCBS 60...0-50
KTTV 65...0-50

MT. SOLEDAD, SAN DIEGO, DIST= 113 MILES

KGTV 25...64-72, good signal
KFMB 55...68-70, fair signal in good weather, drops out in bad weather



**************************************************
****Channel Master 4251 (Long Range Parabolic) With CM-7775 Pre-amp

MT. WILSON, LOS ANGELES, DIST= 15.5 MILES

KTLA 31...0-50
KCOP 32...N/A
KNBC 36...0-50
KCAL 43...N/A
KABC 53...0-50
KCET 59...N/A
KCBS 60...0-50
KTTV 65...0-50

MT. SOLEDAD, SAN DIEGO, DIST= 113 MILES

KGTV 25...75-78, steady signal
KFMB 55...53-55, drops out 3 times a minute



**************************************************
****Channel Master 3017 (Medium Range Yagi) With CM-7775 Pre-amp

MT. WILSON, LOS ANGELES, DIST= 15.5 MILES

KTLA 31...N/A
KCOP 32...N/A
KNBC 36...0-50
KCAL 43...N/A
KABC 53...N/A
KCET 59...N/A
KCBS 60...0-50
KTTV 65...0-50

MT. SOLEDAD, SAN DIEGO, DIST= 113 MILES

KGTV 25...56-64, good signal, can drop out in bad weather
KFMB 55...40-50, can lock in good weather only



Conclusion:

4248 best for multipath rejection, good long distance signal strength. 4228 ok antenna, but did not work as well as the 4248 in multipath conditions. 4251 best long distance capability, but not good for multipath. 4221 could not lock in any multipath signals, ok for line of sight stations. 9095 Winegard quality, but not as good as 4248 in severe multipath. 8800 high quality construction, but average performance. 3017 Good medium sized UHF/VHF antenna when used with a clear line of sight.
I'm not sure if I have much multipath problems though... this could make a difference in the antenna I need according to these results.

[dishrich]

I noticed the "Front to Back" ratio is lower on the Winegard. Is this good or bad (not understanding F/B)?

Unfortunately, the HIGHER the ratio, the better. :( :(

[Sonnie Parker]

I climbed up on the roof and tried to figure out what kind of CM antenna I had but there was no label anywhere. It is obviously an older model because I can't find a match for it on CM's site nor Stark Electronics.

Here's a pic of the antenna:

http://www.snapbug.ws/images/antenna.JPG

I did verify that I can not decouple the VHF and UHF signals. I can amplify the VHF ONLY or COMBINED signal via the 7777, but that's about it for flexibility.

I need to keep the VHF but need a stronger UHF.

Will it work if I extend the mast above the VHF/UHF antenna about 5 feet and install a UHF only antenna?

I have an extra 75 ohm cable already ran into the attic that I can use for the UHF and it will be connected only to the 6000u receiver. I'll keep the VHF/UHF antenna connected to the 5000.

Should I be concerned about interference if they are run on separate cables?

Thanks!

[dishrich]

Why don't you just do what dbspaul suggested, & run your existing combo ant into the VHF in of your 7777, then run the NEW UHF into the UHF in of your 7777 & you're all set. Or, better yet, if you can spring for the money, get a new separate VHF antenna & just put both up through the separate inputs of your amp.

[Sonnie Parker]

Yes I can do this but the signal will then have to be separated again once it gets back to the 6000u and 5000.

I was figuring I'd just pick up another amp for the UHF only antenna and run it separate as to keep my VHF/UHF analog channels on the 5000.

[dishrich]

Yes I can do this but the signal will then have to be separated again once it gets back to the 6000u and 5000.

With a preamp on the ant, a 2-way splitter isn't going to drop your signal level enough to matter... ;) ;)

[Sonnie Parker]

Good, I'll take that route then.


Thanks to all of you for the help.

I'll post the outcome of my set up once completed.

[oljim]

Sonnie the ant in the picture is a CM Quantum 1162 or 1165, I have the 1160 about 2 times as big. It is listed at Stark CM ref chart.

[Sonnie Parker]

Yeah I figured out it is an 1162.

But, I decided not to do anything until our locals get to full power. The one channel that is offering digital is only outputting 5.8kw power right now and it's 50 or so miles away. The others were supposed to have already started broadcasting digital but haven't yet. Once they all get going I'll know better if I really need to add or change antennas.

[Nick]

You can combine signals from 2 or more antennae as long as no two signals are on the same frequency (channel), which is the happy situation you seem to have. Using separate 75 ohm downleads for each antenna, try combining the feeds first without filters, which occasionally will introduce their own interference. This is your simplest solution. If you do have a problem, then use an A/B switch.

Go here (http://www.abc.net.au/reception/tv/co_channel.htm) to get some tips on resolving reception problems.

[Sonnie Parker]

Thanks Nick!

[TV Tech]

Stacking antennas PROPERLY will yield 3db gain MAXIMUM.

And it will make the beamwidth much more narrow.

Also the tests you site done pointed at MT Wilson, look to be questionable.

If you check the site, their tests claim that the 4 bay bowtie antenna outperformed both the 8 bay bowtie AND the 7 foot diameter 4251 that is WELL documented to produce well over 21db gain!

These results are QUITE flawed and were not done under controlled conditions.

The Winegard HD-9032 antenna is by far the highest performance for the buck antenna.
The Winegard HD-9095 is a very heavy duty antenna that holds up better in
harsh areas and since it is end mounted doesn't suffer from pattern distortion from the mast pipe.

What is MUCH more important than number of elements and gimmicks is BOOM length.

In yagi style antennas, boom length is the ONLY sure predictor of performance.

Thus the Winegard HD-9032 at 114.5 inches is the CLEAR king of the corner reflector yagis.

[Jim5506]

Those tests were done with a high power pre-amp on a high sensitivity antenna at 15 miles!!

Most failures were probably due to tuner overload.

No indication of signal without pre-amp - this test is bogus.

[jclewter79]

Ya'll do realize that this thread is 5 years old right? I am sure Sonny has figured out his problem by now.

[Sonnie Parker]

I would like to think I have... :D

[Stewart Vernon]

Your mileage may vary of course... but here's what I have:

I am using a dual antenna setup... One antenna is a directional Terk-style from Radio shack. I have it on top of a bookshelf pointed at the major antenna farm that has most of my local channels.

My 2nd antenna is the 1/4 wave UHF antenna that actually came with my Dish receiver to be used for the UHF remote (I use IR instead). I have this one up on top of my TV, mainly because my PBS station is in a different direction than most of the other local stations.

Both antennas are joined through a standard UHF/VHF splitter. I do have a signal amplifier installed, but it doesn't make much difference on vs off I've found.

Ultimately, I always recommend trying different combinations and buying parts from a place like Radio Shack that has a liberal return policy to allow you to return something that doesn't work until you find a scenario that does.