Results 1 to 3 of 3

Thread: Affect of metal bolts on yagi

  1. #1

    Default Affect of metal bolts on yagi

    Hello,

    I am building a yagi with center frequency of 859 MHz for cell phone. It has 19 elements and is 80" long. It uses a conductive beam with the elements bonded. I have used VK5DJ yagi calculator for dimensions.

    I would like to support it near the center of the beam. I have made a non-metallic stub for it to mount to (pvc) which will be bolted to the mast with 2 quarter-20 bolts. I am wondering if using steel bolts to connect the stub to the beam will have an adverse affect on performance, as they will be in the path of the signal beam.

    Thanks...

  2. #2

    Default

    Anything in the same plane as the elements can cause issues if its physical dimensions allow for resonance.. I would recommend the shortest bolts possible, and if the bolt length necessary is anywhere near half a wavelength, id detune the bolts with an additional strip, wire or piece of metal so that the mounting hardware cannot accept or re-radiate power.

  3. #3

    Default

    Quote Originally Posted by brandon lind View Post
    Anything in the same plane as the elements can cause issues if its physical dimensions allow for resonance.. I would recommend the shortest bolts possible, and if the bolt length necessary is anywhere near half a wavelength, id detune the bolts with an additional strip, wire or piece of metal so that the mounting hardware cannot accept or re-radiate power.
    Thanks. I decided to go with non-metallic bolts. I'm using nylon for now as I just happened to have them lying around, but I'm going to look around for something stronger, FR-4 or something like that, which I think will be UV resistant as well.

Tags for this Thread

Bookmarks

Posting Permissions

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