Roof top aerial

fatbelly
fatbelly Forum Participant Posts: 438
100 Comments
edited October 2019 in Caravans #1

Hi All, we're currently on our favourite CL for a week. The TV reception on this site  through our roof top aerial has always been average. The person on the next pitch said my aerial was in the wrong polarity & I should tilt the aerial into the vertical. I did this & the reception greatly improved.  What determines which polarity we should put the aerial in. Can someone please explain it all to me.

Thanks 

Comments

  • SteveL
    SteveL Club Member Posts: 12,310 ✭✭✭
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    edited October 2019 #2

    With a horizontally polarised signal the electromagnetic waves vibrate / oscillate in a horizontal plane. Whilst in a vertically polarised signal they vibrate / oscillate in the vertical plane. Hence the reason the directional status aerial can be horizontal or vertical, as it enables it to aline with the signal. As far as I know the main transmitters are horizontally polarised, whilst local repeaters in more remote areas are vertical. This avoids signal conflict between the two. In general the local repeaters don't carry the full range of freeview programmes. So you only get 20/30 instead of 100 +.

  • Whittakerr
    Whittakerr Club Member Posts: 3,472 ✭✭✭✭
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    edited October 2019 #3

    Fatbelly.

    I have an app on my phone called Antenna aligner. It indicates which direction to point the aerial to receive the maximum signal and also tells me if it should be horizontal or vertical.

     

  • lornalou1
    lornalou1 Forum Participant Posts: 2,169
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    edited October 2019 #4

    I use the same app. Great tool for best reception aligning.

  • Freddy55
    Freddy55 Club Member Posts: 1,810 ✭
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    edited October 2019 #5

    That’s handy to know👍

  • Amesford
    Amesford Club Member Posts: 685 ✭✭✭
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    edited October 2019 #6

    The reason for the different polarisations is it helps to cut down the co channel interference between the different TV transmitters. Having the aerial wrongly aligned can cut the signal by many decibels as you have found out, so as already mentioned get the phone app or take a look at the aerials on the nearby houses 

  • Simon100
    Simon100 Club Member Posts: 666 ✭
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    edited October 2019 #7

    An app called 'freepoint UK' shows direction and polarity.

  • mickysf
    mickysf Forum Participant Posts: 6,474 ✭✭✭
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    edited October 2019 #8

    This website should answers all your questions  and more!wink

    https://www.aerialsandtv.com/touringaerials.html

  • richardandros
    richardandros Club Member Posts: 2,683 ✭✭✭
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    edited October 2019 #9

    I also use it and it's good.  Just make sure that when you use your compass App to work out where to point the aerial, that you get out of the van and away from any magnetic influences, to ensure that you get the aerial pointed in the correct direction. 

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