UHF antenna pulled up a tree

[dickie757]

My idea is based on a project I did a few years ago.

Today's project: put a UHF 443 MHz antenna on a rope and haul it up tree.

Years ago project: get an interface/connection for a discriminator tap for a Bearcat 760 scanner.

The interface I ended up using was the remnants of an old wifi router and antenna. I salvaged the router case RP-SMA panel mount jumper from radio board, and disassembled the antenna to use that to connect to the audio input.

Here is the relevance to today: the wifi antenna is constructed in such a way that the coax from the connector goes into a small pipe. The distance from the O.D. of the coax to the I.D. of the pipe is approx the diameter of the coax. The coax shield connects to the pipe, then the center conductor continues to free space. The free space center and pipe are roughly equal in length.

I think this is a dipole, no?

Today's idea is make a UHF antenna the same way, so it can be pulled up into a tree.

I have made several antennas of differwnt types following directions, and they worked perfectly. The closest I can find to this idea is a collinear.

Eventually, I do want to make a multi-element collinear from scratch, but "Not today!"

I look forward to responses.
Dickie

 

[mmckenna]

I think this is a dipole, no?

Sounds like a sleeve dipole.

 

[dickie757]

Those are the words I needed. Thanks.

My plan: LMR400 up through center of pool noodle through pipe. N male bonded to pipe. N barrel connector. N male with only center conductor at proper length. Center conductor tied to rope. Tree.

 

[K7MEM]

That kind of antenna is also known as a Coaxial Antenna. I know your looking for a much higher frequency, but this article on a 10 Meter Coaxial Antenna may provide some help, construction wise. I have a Coaxial Antenna that was made by Radio Shack for 11 Meters (18' tall). I use a coax stub to give me a match on 10 Meters.

 

[dickie757]

Awesome. At some point, I do want to put a 10m antenna up. I have a length of copper fuel pipe left over that has radiator written all over it. For the sleeve, I plan on using expanding flex duct, like dryer vent tube.