FPVLAB

image
Results 1 to 5 of 5

Thread: New double stacked dipole antenna looks very promising

  1. #1
    Forum Member
    Join Date
    Aug 2011
    Location
    Italy
    Posts
    46

    Exclamation New double stacked dipole antenna looks very promising

    Guys I have been testing with the IBCRAZY turnstile in the past few days.
    My need was (is) to have a decent gain in a CP omni, for both uhf and video.
    I have used a 1/4 wave matching stub to stack two dipoles at 1/4 wavelength distance. Needless to say this antenna can be buried in a wing with horizontal polarization if side fed, and it can be also buried in a zephir wing if set with vertical polarization which I prefer, as the antenna is showing a 2.12db gain.

    My tests so far are ground based and it beats the hell out of the vertical whip on the fatshark 100mw transmitter.

    In fact with a stock whip on 2.4 on the tx and a stock whip on the fatshark gogles, I would leave the video transmitter and cam in the attic (all brick and cement walls with steel ), and walking down the stairs I'd get some disturbances already, then on the middle floor I'd have picture intermittently, as I moved my head around, I'd continue to the bottom floor and picture would degrade even further, with only occasional locks in certain positions of the head.

    I put the double stacked antenna on and I had perfect picture all the way through the three floors.

    Outside picture is perfect up to 2KM. with stock whip on the fatshark.

    I don't know if I've been lucky, but something I did with this is def. right.

    If there are any more beta testers out there, please let me know if you try it what the quality is like.Click image for larger version. 

Name:	double stacked dipoles.jpg 
Views:	466 
Size:	89.4 KB 
ID:	3120Click image for larger version. 

Name:	double stacked dipole 2.jpg 
Views:	292 
Size:	64.9 KB 
ID:	3121

  2. #2
    Forum Member
    Join Date
    Feb 2011
    Location
    Charlotte, NC
    Posts
    1,150
    Do you have instructions on how to build this? I would like to maybe try it for a 5.8g 200mw system. I currently have self-made SPW an CL on it, but am only getting about 1km out of it in the air, and I'm looking to try another omni option before trying a helical on the ground.

  3. #3
    Forum Member
    Join Date
    Aug 2011
    Location
    Italy
    Posts
    46
    I can come up with instructions, even though it's very simple, just make a normal dipole for your frequency and solder it, measure the length, for 5.8g it's 24mm tip to tip.
    Than you make another dipole identical to it, and solder a small piece of coax (possibly 75ohm) cut the coax to 1/4 wavelength, which is about 6mm for your frequency, and solder the ground to the ground of the other dipole, and the feed to the feed of the other dipole at 90 to it.
    At your frequency it's a bit difficult to match the 1/4 wave stub, but that's why we have many channels!

  4. #4
    Forum Member
    Join Date
    Aug 2011
    Location
    Italy
    Posts
    46
    this is 1 db more than your cloverleaf, if the antenna works well you should be able to go 1.2km from the extra db.
    Keep your cables short.

    And if you use a SWP on the reciever, I would try with a standard whip on the receiver first.

  5. #5
    Forum Member
    Join Date
    Aug 2011
    Location
    Italy
    Posts
    46
    The first test of the antenna is in. A friend of mine built one and tested it, but results are not entirely satisfying. I will have to change the matching solution with 2 stubs of 75 ohm cable for each of the dipoles, set at 1/4 wave apart from each other, all feeding from a 50ohm line.
    Hopefully I will have a better match.
    My friend was experiencing multipath problems and also video got bad when banking left with the motor on.
    10,000 ft, 3km was reached but the quality is not as I expected.
    Gotta go back and do my homework. I am waiting for swr/power meter so I can tune an antenna and send it to a few people for testing.

Similar Threads

  1. Sander style (dipole) or Thomas Scherrer style antenna for Rx
    By Sp1k3 in forum Video Aerial Systems
    Replies: 6
    Last Post: 9th March 2014, 03:43 PM
  2. Build IBCrazy's 10dbic CP Double Quad antenna
    By IBCrazy in forum Video Aerial Systems
    Replies: 101
    Last Post: 27th October 2012, 12:29 PM
  3. Video TX connector / dipole antenna query
    By Ian Davidson in forum IFR - Video Link Discussion
    Replies: 0
    Last Post: 16th November 2011, 02:29 PM
  4. Replies: 0
    Last Post: 13th September 2011, 05:52 AM
  5. The 9dbic CP double Quad
    By IBCrazy in forum Video Aerial Systems
    Replies: 10
    Last Post: 22nd March 2011, 04:33 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •