Welcome to PhantomPilots.com

Sign up for a weekly email of the latest drone news & information

Antenna's

Discussion in 'General Discussion' started by justin00, Oct 14, 2014.

  1. justin00

    Joined:
    Sep 19, 2014
    Messages:
    1,143
    Likes Received:
    25
    Location:
    Australia
    So I'm trying to understand antenna's and all that stuff.. I have been reading wiki's and various pages on the internet
    to get a better understanding.. I'll admit I am having a tough time understanding and taking it all in.

    A question I do have.... In a lot of the pages I have read (and in a few threads here) people mention if you go from say
    LHCP to Linear you will get a 3db loss... Now my question is.. What sets the Phantom as LHCP ?

    Is it the 5.8GHZ TX transmitter that is configured for LHCP ? Or is the aerials on the Phantom that are LHCP
    and that is why the change to linear gets 3db loss ? Or is it something else I am not understanding ?

    Reallly just trying to get my head around this... :/

    Thanks heaps
     
  2. Happyflyer

    Joined:
    May 5, 2014
    Messages:
    1,805
    Likes Received:
    98
    Location:
    Cold, Cold, Michigan
    I could put my 2 cents worth of info on your question(s) but my knowledge is mostly with circular and linear polarization with satellite TV. I am sure one of the antenna people will give you some qualified answers soon.
     
  3. SteveMann

    Joined:
    Aug 27, 2014
    Messages:
    1,977
    Likes Received:
    653
    Location:
    Westford, MA
    It's the same in any medium. Receiving a CP signal on a linear antenna is at least a 3dB loss.
    Signal polarization is determined by the antenna.
     
  4. Happyflyer

    Joined:
    May 5, 2014
    Messages:
    1,805
    Likes Received:
    98
    Location:
    Cold, Cold, Michigan
    Interesting it is only a 3dB loss. Because if you try a linear LNB on your dish and try to get a CP signal from a satellite, you will get "0" or nothing.
     
  5. N017RW

    Joined:
    May 2, 2014
    Messages:
    6,257
    Likes Received:
    1,619
    Location:
    Palm Beach Co.- FL
  6. Happyflyer

    Joined:
    May 5, 2014
    Messages:
    1,805
    Likes Received:
    98
    Location:
    Cold, Cold, Michigan
    Purrrrrfect N017RW, well done.
     
  7. SteveMann

    Joined:
    Aug 27, 2014
    Messages:
    1,977
    Likes Received:
    653
    Location:
    Westford, MA
    I said "at least" 3dB. That's what the pure lab math would indicate barring all other losses. In real life I wouldn't be surprised to see a 6dB loss. Your satellite LNB is already so close to a signal dropout that a few dB from a rain shower will cause a temporary interruption.

    What satellite service uses linear LNB's?
     
  8. justin00

    Joined:
    Sep 19, 2014
    Messages:
    1,143
    Likes Received:
    25
    Location:
    Australia
    edit.. n/m can't delete post.
     
  9. justin00

    Joined:
    Sep 19, 2014
    Messages:
    1,143
    Likes Received:
    25
    Location:
    Australia
    If that is the case, why do I read there a 3db loss going from LHCP to Linear ???
    I don't get it.. or is the RX antenna (on the phantom) determining the polarization ??

    *edit* read articles and I think it says TX antenna needs to match RX antenna or there will be loss..sooo is the RX on the phantom not Linear ?? thought those 2 little cables dangling would be linear ?? are they LHCP ??

    Thanks heaps all for the responses :)

     
  10. Happyflyer

    Joined:
    May 5, 2014
    Messages:
    1,805
    Likes Received:
    98
    Location:
    Cold, Cold, Michigan
    F.Y.I
    It is called Free To Air or FTA. There are more channels coming from the satellites than you would ever believe that are not scrambled and 100% legal to receive if you have the correct equipment. They use linear transmission. I can receive programs from my dish farm that you can't even get from the popular providers. I also subscribe to Dish network.
    Providers like Dish and Direct use circular polarization.
     
  11. Buckaye

    Joined:
    Aug 24, 2014
    Messages:
    1,557
    Likes Received:
    420
    Location:
    Orlando
    oh no you didn't LOL LOL :lol:
     
  12. justin00

    Joined:
    Sep 19, 2014
    Messages:
    1,143
    Likes Received:
    25
    Location:
    Australia
    Can anyone tell me if 2 antenna's on Phantom are linear or polarized ?

    I'm still not getting this..... the page N017RW posted up said the tx/rx decide if its linear or polarized.. which makes sense... but then why do I lose 3db if I use my linear antenna ???
    Is the RX polarized ??
     
  13. SteveMann

    Joined:
    Aug 27, 2014
    Messages:
    1,977
    Likes Received:
    653
    Location:
    Westford, MA
    No, it doesn't. The only mention of the TX/RX was: "All antennas sold with video transmitters and receivers are linear polarized."
     
  14. justin00

    Joined:
    Sep 19, 2014
    Messages:
    1,143
    Likes Received:
    25
    Location:
    Australia
    Errrm so what is it then that decides?

    Im guessing the 2 wires dangling down legs are LHCP and that means the TX should also be LHCP ??
     
  15. N017RW

    Joined:
    May 2, 2014
    Messages:
    6,257
    Likes Received:
    1,619
    Location:
    Palm Beach Co.- FL
    Justin00,

    The short answer is the both the transmitter and the dual antennas on the receiver of the P2s are linear and which ever way the are oriented at any given time determines their polarity. They are intended to be oriented as vertical polarization. For best results keep both the Tx and Rx antennas parallel to each other.

    Please go to this link at RCGroups:
    http://www.rcgroups.com/forums/showthread.php?t=1494024

    It is well written and will save us a lot of typing :lol: