0
$\begingroup$

Speaking of the antenna in this question: What kind of 2 meter antenna is this?

The connections are rusted and corroded so I'd like to rewire it. If I move the shield from where it is currently attached, down to the base, will it change the characteristics appreciably?

My hope is to be able to replace the coax and install an SO-239 at the bottom, then just wire up the center conductor back where is was originally attached.

(There are a few more pictures with the original question.)

The antenna Connections Base

$\endgroup$
  • 1
    $\begingroup$ For what purpose, exactly? Operation on which bands? Both the 440 MHz and 146 MHz, or just either of them? Are you sure it's worth the effort, ie. aren't there well-known designs that, with the hardware that you can get by scrapping this antenna, would work at least as well? $\endgroup$ – Marcus Müller Jul 30 '17 at 19:34
  • $\begingroup$ @MarcusMüller It works on both 2m and 440 currently. And yes, it could probably be reworked and made better. But it was built around 35 years ago by a friend who is now SK. We are going to keep the antenna as-is because of that. I just want to clean it up a little. It may never actually be placed into service again but I would still like it to work if need be. $\endgroup$ – Lance Jul 30 '17 at 23:47
2
$\begingroup$

Currently, there's a section of coax transmission line that runs from the base to the feedpoint where the center conductor exits the vertical tube.

If I'm understanding correctly, you propose to replace that section of coax with a single conductor. In that case, you'll still have a coaxial transmission line in effect, with the vertical tube acting as the "shield".

The fields within this transmission line do not radiate, so the radiation pattern would remain unchanged. However, since this transmission line isn't designed to be any particular impedance, the feedpoint impedance will not be what it was before modification.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.