antenna material.

[sleeplesman1]

after reading what i can about antenna and frequencies i built a 1/2 inch copper pipe j pole antenna. it works great at the height i have it now.. looking forward to getting it above my roof line next. my question now it. that one is 1/2 inch copper pipe.. can anyone tell me what the effect is if I build one out of 3/4 inch copper pipe. i have enough kicking around to build one. is it worth my while to try it? I figure maybe it would be a real tough antenna to put atop a 30 foot tower.. the tower is empty anyway. any thoughts on this one?

thank you for any response.

 

[LtDoc]

I think either one of them would do fine on a tower. As for the larger diameter used to make one, I'm not so sure it would make any significant differences at all. If you've got nothing to do and wanna try it, why not? Then you tell us!
- 'Doc

 

[n5ims]

A larger diameter antenna (all other factors remaining the same) generally will have somewhat larger bandwidth than a similar antenna that's a smaller diameter. This may not matter since a normal J-Pole will fully cover the band they're normally used for on the VHF or UHF ham bands.

The larger diameter construction may also provide additional strength, but this is offset a bit by a greater wind load. Assuming the antenna is well made, the additional strength should well overcome the additional wind load moving from 1/2 to 3/4" pipe since the J-Pole design isn't a high wind load antenna.

 

[sleeplesman1]

3/4 pipe

think ill try the 3/4 pipe on the jpole this week. i have just enough to build. will test for the next few days and see what happens on the same mount as the 1/2 inch for comparison.
thanks for all replies.

 

[sleeplesman1]

so much for a 3/4 jpole from on site stuff.. ran over it today and ruined the piece.. ill wait till i get more. in the mean time.... any one know where to get twin lead antenna wire in ontario canada? its not to be found. Im looking at ordering it from a radio shack in the states at this rate.

 

[k3cfc]

I just built a vhf/uhf with aluminum angle and 3 3/8 inch rods. preforms well and very lite. could mount it on pvc pipe.

 

[mmckenna]

You can probably order the cheap 300 ohm twin lead TV stuff from Radio Schmuck, but you can get nicer stuff from any of the ham radio dealers.

Although, for what you are doing, the basic stuff will work just fine.

There was a local ham club that made J-poles and sold them at the local swap meets. Not sure if they still do it or not. They were mostly aluminum rod and very well made. I bought a 2 meter and a 70 cm version for probably less than $20 each. I used those for a long time. Good antennas. Not sure whatever happened to the 70cm antenna, but the 2 meter antenna is used on a pole with my brother in laws toy-hauler trailer.

I always liked the copper pipe versions, never did make one though. Maybe one of these days I will. I did make a lot of antennas in my earlier years, including a few beams.

 

[sleeplesman1]

made my first j pole for the house out of the 1/2 inch pipe.. works realy well. i can hear fire services from bellville ontario.. thats about 80 km/50 miles from here as the crow flies. cant wait to see what i get once its up above the roof line. Id just like to build a few antenna. one for the camper is next.. thats why i would like twin lead.. a slim jim for the camper.. quick and easy to put up once we get the camp set up.

 

[sleeplesman1]

im hoping to make a dipole from an old cb antenna and i have some 36 inch bronze rods for my radials, or ground plane.

 

[mmckenna]

Sounds fun. CB dipoles are easy to make and are great portable antennas. CB J-poles get to be pretty big, but could be done also, if you had a tall enough support. A ground plane CB antenna would probably be a good all around antenna. The ground radials will give it a nice radiation pattern.

As I'm sure you know, VHF and UHF likes to work line of site. The higher you can get your antenna up, the farther off the horizon is that it "sees".

A copper pipe J-Pole with soldered joints and capped ends, along with soldered electrical connections would be one nice set up. The copper will get a nice patina in the weather and help it blend in really nice. 3/4" pipe should work well and be rigid enough to last. It would be interesting to play around with something like 2" copper pipe and see what kind of bandwidth you could squeeze out of it. Setting one up at 160MHz or so would cover a pretty popular portion of the band. Another one on UHF, maybe up in the 460 range would cover UHF well. I had those ones for 2 meters and 70cm and they worked really well.

 

[LtDoc]

If you can't find any 'twin-lead' or 'ladder-line', then just make some. The kind of wire used isn't all that important. If it's to be a 'stand-alone' kind of antenna then it has to be able to 'stand' up with out support. Or, just provide that 'support' in some way. That 'support' thingy is fairly easy for 2 meters and up, not so easy for under 2 meters. That's a 'mechanical' thingy, not electrical. How about the size of the wire? Diameter can make some difference in 'bandwidth' but it isn't a 'miracle' worker and usually doesn't amount to a lot of benefit other than the 'mechanical' aspects.
- 'Doc

(You ran over that thing? I ain't never done that sort of thing! ... and I hope I never do again, aggravating, huh?)

 

[sleeplesman1]

i was thinking making the wire out of speaker wire mounted on something to keep the spacing even. I am looking at all different materials to build out of in the yard. I guess this is what ham radio is about.. invent and make what you can.. enjoying it so far.

 

[LtDoc]

It really amounts to what what you have available and what's most convenient to use in a particular circumstance. I have seen some pretty 'odd' antennas and made a few too. Ever see the aluminum step-ladders with rubber/plastic feet? It's insulated from 'ground', right? If it's the right length/height it'd made a usable antenna. How about loading a railroad track? Two rails, two terminals, it does work (done it). Not good by any means but possible. All an antenna is, is an electrical conductor of the right length and 'shape' for the frequency of use. From there, it can be almost anything... almost.
- 'Doc

 

[k3cfc]

I used a pair of crutches once. but had to give em back to gran mother.

 

[majoco]

Perhaps model railway "OO" or "N" gauge track would make good twin feeder........I feel an experiment coming on..... :roll: