TV antenna selection

Discussion in 'General Electronics Chat' started by Georacer, Aug 21, 2012.

  1. Georacer

    Thread Starter Moderator

    Nov 25, 2009
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    In my grandmother's house, we need to replace the old TV antenna whose performance is starting to drop over the last years.

    As you can read, I live in Greece. The house is in a mountainous area, quite surrounded by mountaintops. The closest transmitter isn't exactly visible. I 'm interested in the UHF band.

    What type of antenna should I look for?

    Thanks in advance.
     
  2. bertus

    Administrator

    Apr 5, 2008
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    Georacer likes this.
  3. Georacer

    Thread Starter Moderator

    Nov 25, 2009
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    bertus: linking you to sites of your own country.

    Gotta love him.
     
  4. cork_ie

    Member

    Oct 8, 2011
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    I assume Greece is going Digital like the rest of Europe before the end of 2012.

    What is the channel spacing ?
    . If the channel frequencies are close together then a directional Yagi should do,
    Channels, Aerial Group, Colour Code:
    21-37 A Red
    35-53 B Yellow
    48-68 C/D Green


    If you have wide channel spacing you will need a wideband aerial
    21-48 K Grey
    21-68 W Black
    35-68 E Brown

    If I were getting an aerial for my Granny I would see what the neighbours are using in the same location. They will also give you an indication of direction and polarity.
     
  5. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    The Netherlands, where I live has gone digital already.
    We use a DVB-T system called Digitenne.
    When you do not have a subscription, you can look to the 3 non-commercial stations.
    With a subscription (wich cost about 9.5 euro a month), you will get about 20 stations.

    Bertus
     
  6. Wendy

    Moderator

    Mar 24, 2008
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    I used to live in that kind of environment. Best solution is a directional antenna and a rotor, so you select the best set up. If the signal is weak you also need a booster, they used to be common, not sure today. Basically an antenna preamp, to amplify weak signals.
     
  7. #12

    Expert

    Nov 30, 2010
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    When I had to eliminate reflections from nearby mountains I used a log-periodic antenna...the kind with saucers on the front. They can have an aiming window as small as 5 degrees. (That means a huge front to rear ratio.) That was Los Angeles. When I had to get Chicago, I used the antenna in the first post...we call it a "screen door with bow ties". I picked up 3 different cities. Not as directional as you might like.
     
    Last edited: Aug 21, 2012
  8. Georacer

    Thread Starter Moderator

    Nov 25, 2009
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    There is already a commercial signal amplifier in the existing setup, but it's pretty old too and a bit weather-beaten.

    Greece is indeed supposed to turn to digital by the end of the year. It's been 6 months that some areas of the country receive digital signal and last month, one of the two major transmition spots in Athens turned digital too.
    I simply turned my antenna to look to the other one.

    I really doubt if the analog signal will be abandoned coutry-wide by the end of the year. Schedules isn't exactly the strong point of this country.

    Thank you all for your suggestions. Too bad the answer isn't a straighforward one, judging from the diversity of your responses.
     
  9. cork_ie

    Member

    Oct 8, 2011
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    The Bowtie grid is a variation of the Colour King aerial .
    It is a superb aerial , great for wideband but unfortunately very prone to reflections.
    I live inside in a Glen , with very difficult reception and after a huge amount of trial and error found a very long Yagi the best option by far.

    An ideal 20 element Yagi can theoretically give 19 dBd forward gain.
    20 element is rare and expensive so you could try something shorter first, 10 or 12 element should do in most cases.

    As mentioned above , I would definitely agree that a signal booster is well worth fitting. Especially when the transmitter is out of your line of sight.
    They are widely available at small money. Variable gain is best in your situation
     
  10. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    A signal booster will only help if you already can receive some signals.
    You can not boost nothing to something.

    Bertus
     
  11. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    Do you know what channels you are trying to receive? The new "digital" antennas are built to receive all the UHF channels (14 -83) and the upper VHF band (7-13).

    If you have no channels of interest in the low VHF band (2-6) just get a new digital antenna. If you have some in low VHF, you need a broadband antenna.

    Here is an example of a high gain digital antenna for upper VHF-UHF:

    http://www.solidsignal.com/pview.as...tdoor-HDTV-Antenna-(HBU44)&c=TV Antennas&sku=

    another good one:

    http://www.amazon.com/Winegard-HD7698P-HDTV-VHF-UHF-Antenna/dp/B001DFTGRY
     
  12. cork_ie

    Member

    Oct 8, 2011
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    She has already been receiving a signal for years , but the performance has dropped off and he is replacing the aerial with a new one.
    It is a fair assumption that the signal level is adequate but with DVB-T pixalation can become an issue in rain.
     
  13. Georacer

    Thread Starter Moderator

    Nov 25, 2009
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    Roughly from 21-69. The upcoming digital transmitions are in that range too.

    For now I am aiming to reach the analog channels. To my experience so far, digital channels reach the antennas much more clearly in the same distance and without interference so I don't think the transitions from one format to another will be an issue. Do I assume wrong?
     
  14. cork_ie

    Member

    Oct 8, 2011
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    Hi Georacer,
    You assume right , just that the bit of "snow" in analogue reception when it rains or if you have trees etc. growing in the signal path is not very noticeable.
    With Digital it is either perfect picture or breaking up called pixelation (see attached image) , when the signal level drops.
     
  15. KJ6EAD

    Senior Member

    Apr 30, 2011
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    Assorted additional antenna adjustment advice:

    If all of your transmissions come from the same location, you don't gain anything with a rotor.

    If your signal is knife-edging over a hill then angling the antenna above or below horizontal as well as rolling the polarity slightly may be optimal.

    It's a lot easier to adjust the antenna if you have a small TV connected on the roof while adjusting it to directly observe the effect of adjustments.

    Go through the adjustments in order: azimuth (yaw), elevation (pitch) and polarity (roll) then repeat to fine tune.
     
    Last edited: Sep 20, 2015
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  16. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    It's very odd that an antenna's performance would degrade, it's usually caused by a bad transformer or deterioration of the cable downlead.

    My antennas are 25 years old and have never had any degradation, but the coax lines do have to be replaced about every 8 - 10 years. But going to a newer antenna with higher gain will give better reception.

    BTW: use best quality RG-6 cable to minimize signal loss. Use "weatherproof" transformers at the antenna and seal them very well with grease and tape to keep water out.
     
    #12 likes this.
  17. Georacer

    Thread Starter Moderator

    Nov 25, 2009
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    The antenna is so old we have lost track of its age. My father found it installed at his father's-in-law house 30 years ago.

    I 'm willing to drop a penny or to for the local economy to replace a generation-old apparatus.

    Edit: The coax has been replaced relatively recently.
     
    Last edited: Aug 21, 2012
  18. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    Last edited: Aug 21, 2012
  19. crutschow

    Expert

    Mar 14, 2008
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    The advantage of a booster mounted at the antenna is that it amplifies the signal before any losses from the cable between the antenna and the TV.

    Look for one with a low noise figure.

    The degradation you are observing with the old antenna may be due to the amplifier failing as well as the antenna weathering.
     
  20. #12

    Expert

    Nov 30, 2010
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    I'm with bountyhunter. I never throw an antenna out until I can't replace the bolts that hold the connections on. If you can install it in the attic, it will never wear out.

    AntennaCraft and Wineguard are both good brands but, the Wineguards are always more expensive for the same size antenna.

    I use, "electricians putty" on the connectors. The connections will be good as new after 10, or maybe even 20 years. The "best" cable right now is RG-6 Quadshield.

    Radio Shack used to sell an adequet pre-amp with FM trap/or not, and adjustable gain. I don't rememeber when because I've had the same one working for over 30 years.

    Yes, I'm too cheap to pay for cable TV.
     
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