j-pole in PVC

[N9ZVV]

I'm building a 2 meter J-pole and it's going in a piece of PVC pipe,and all the stuff I have read they put the antenna inside a piece either 1/2" or 3/4",But I just happen to have a piece that is 1 1/4" in diameter,and was wondering if the diameter of the pipe makes any differance?(besides just being larger and heavier)

Thanx in advance.

 

[Hoofy]

Are you making the antenna from a piece of 300 ohm tv leadin wire? If you are, then you will need to support it inside the 1 1/4 pipe or it will sag down inside the pipe.

Depending which kind of plastic pipe you are using may make a difference in the performance of the antenna inside. The thicker side wall pipe may act like a mild attenuator.

Try it and see what happens you won't be out anything but some time.

 

[N9ZVV]

I forgot to mention, it will be made out of twin lead,it will also be supported by a wood dowel,I guess I didn't think about the thickness of the pipe,I'll just give it a try and see what happens.
Thanx for the reply.

 

[specman]

I've made many many j-poles, co-linears and other designs inside PVC piping. The diameter used will not affect the design, however the thickness of the pipe will. I can't remember the exact velocity factor of the PVC I used but I had to end up adjusting my designs slightly compared to the same antenna outside of the PVC; they were shortened slightly. In the case of a J-Pole make sure there is some allowance to adjust the feed slightly if you are using this for transmitting purposes.

The thing I like about these types of antennas is that they are very weatherproof and easy to hang off of trees etc.

Good luck!

 

[N5TWB]

Assuming it is easily available to you, fiberglass tubing is more transparent to RF than is PVC and might save you some of the steps described in the above posts.