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Dual UHF Antennas?

Discussion in 'Local Reception' started by Sonnie Parker, Oct 2, 2003.

  1. Oct 2, 2003 #1 of 35
    Sonnie Parker

    Sonnie Parker Legend/Supporter DBSTalk Gold Club

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    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.
     
  2. Oct 2, 2003 #2 of 35
    Mark Lamutt

    Mark Lamutt Your Neighborhood Liasion

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    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.
     
  3. Oct 2, 2003 #3 of 35
    Sonnie Parker

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    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?
     
  4. Oct 2, 2003 #4 of 35
    Mark Lamutt

    Mark Lamutt Your Neighborhood Liasion

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  5. Oct 2, 2003 #5 of 35
    Sonnie Parker

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    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
     
  6. Oct 2, 2003 #6 of 35
    Mike123abc

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    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.
     
  7. Oct 2, 2003 #7 of 35
    jimisham

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    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.
     
  8. Oct 2, 2003 #8 of 35
    DBSPaul

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    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.
     
  9. Oct 2, 2003 #9 of 35
    dishrich

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    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.
     
  10. Sonnie Parker

    Sonnie Parker Legend/Supporter DBSTalk Gold Club

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    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.

    [​IMG]

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

    dishrich Hall Of Fame

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  12. DVDDAD

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    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!
     
  13. Sonnie Parker

    Sonnie Parker Legend/Supporter DBSTalk Gold Club

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    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.
     
  14. DBSPaul

    DBSPaul Mentor/Supporter DBSTalk Gold Club

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    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.
     
  15. Sonnie Parker

    Sonnie Parker Legend/Supporter DBSTalk Gold Club

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    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.
     
  16. dishrich

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    They ARE - ALWAYS have been...

    Hardly, THIS is MUCH bigger & better than that:

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

    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.
     
  17. Sonnie Parker

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    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)?


    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.
     
  18. DBSPaul

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    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.

    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.
     
  19. Sonnie Parker

    Sonnie Parker Legend/Supporter DBSTalk Gold Club

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    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.
     
  20. Sonnie Parker

    Sonnie Parker Legend/Supporter DBSTalk Gold Club

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

    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.
     

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