Results 1 to 7 of 7

Thread: Request RF/Groundplane info

  1. #1
    CarlOrton's Avatar
    Join Date
    Jul 2011
    Location
    DFW Area
    Posts
    729

    Request RF/Groundplane info

    Hi, All;

    I'm trying to decide on where to place the transponder antenna. This is a "regular" pre-ADSB small monopole antenna. This is going on a Zenith Cruzer, all aluminum.

    My question is: How close to the edge of the structure may I place the antenna? IOW, I don't know if I need to have a minimum distance in each direction from the mounting hole, or is having plenty of room in the other 3 directions sufficient. I *know* a center-placed antenna would be better, I just don't know how much I lose with an edge-mounted antenna.

    Thanks for any info you provide!

    Name:  Presentation1.jpg
Views: 907
Size:  7.5 KB

    Carl Orton
    Sonex #1170 / Zenith 750 Cruzer
    http://mykitlog.com/corton

  2. #2
    FlyingRon's Avatar
    Join Date
    Aug 2011
    Location
    NC26 (Catawba, NC)
    Posts
    2,627
    A quick calculation would tend to indicate that 8 cm (just over 3") would be fine.

  3. #3
    CarlOrton's Avatar
    Join Date
    Jul 2011
    Location
    DFW Area
    Posts
    729
    Thank You, Ron; may I ask how that number was calculated (I know digital. RF, ehhhhhhhh.....)

    Carl Orton
    Sonex #1170 / Zenith 750 Cruzer
    http://mykitlog.com/corton

  4. #4
    FlyingRon's Avatar
    Join Date
    Aug 2011
    Location
    NC26 (Catawba, NC)
    Posts
    2,627
    A quarter-wave vertical (what you have here) needs a quarterwave counterpoise. A quarterwave at 1030MHz is about 29m (neglecting velocity issues). So a quarter of that plus a little more fudge for velocity factor.

  5. #5
    Scooper's Avatar
    Join Date
    Jul 2016
    Location
    Santa Rosa, CA
    Posts
    65
    Quote Originally Posted by FlyingRon View Post
    A quarter-wave vertical (what you have here) needs a quarterwave counterpoise. A quarterwave at 1030MHz is about 29m (neglecting velocity issues). So a quarter of that plus a little more fudge for velocity factor.
    Ron, I think you mean a full wavelength at 1030 MHz is about 0.29 meters, so a quarter wavelength counterpoise would be 0.0725 meters, or 2.8543307 (~3) inches.
    - Stan Cooper (K4DRD), Private Pilot ASEL, LSR-I, EAA 115792 Lifetime Member, EAA Chapter 124
    Experimental AMD CH601XLi-B, N601KE, KSTS



  6. #6
    FlyingRon's Avatar
    Join Date
    Aug 2011
    Location
    NC26 (Catawba, NC)
    Posts
    2,627
    Yeah, 29 cm or .29m. Careless typing on my part. The answer is the same.

  7. #7

    Join Date
    Aug 2011
    Location
    Alabama
    Posts
    2,236
    Three inches? Cool.

    Why that?

    * Glassy eyed stare *

    Yeah, three inches. Cool.
    The opinions and statements of this poster are largely based on facts and portray a possible version of the actual events.

Posting Permissions

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