J-pole antenna

[Mark W.]

I have one on my roof made from reinforced 1/2 copper water pipe with a fiberglass temp. fence post shoved up inside it. I run a 50 ohm Mini 8 coax lead in.

some construction photo's are here:

http://s65.photobucket.com/albums/h217/UJ78/Antenna/

 

[John James]

Mark, tell us about performance if you don't mind.
Thanks.

 

[Mark W.]

Well not sure how to judge the performance. I can almost see the broadcast antennas from the station I listen to the most.

BUT the few times I have tried DXing I have been very impressed at the number of low power stations I have been able to pull in.

we have a 135watt college station KWBX 90.3 FM in Salem it is only 12.2 miles away but it is on the far side of a hill much higher then the antenna which is just a short tower on top of one of the buildings.

The Radio Locator site puts me on the very edge of fringe reception for this station and I can pull it in pretty good in Mono (not even sure they do Stereo it is a religous program)

I can also pull in a 10 watt station in Dallas, Oregon that has it's transmitter in Falls City about 35-40 miles away but almost in a straight line following a slot in the hills along the Willamette river. I see that that station is no longer listed on the Radio locator web site. So I don't have details.

I'm very happy with the way the stations I listen to come in if the stations signal is clean so is my reception. Compared to a 300 ohm wire Di Pole antenna the J Pole is outstanding.

I also have a Modified Qubic Quad (double square wire loop) antenn on the ceiling in my office and the J Pole and it are pretty close in pulling power.

My plans in the future are to go to a manually adjustable YAGI antenna. I have the ability to run a antenna mast through the roof into the Alcove under the stairs my system is in so that all I would need to do is manually turn the shaft to point the antenna. But that project is a ways off. Most likely I'll do it when I put on a new roof in a year or two.

And for those thinking about that. We are in a VERY low risk of lightning area and I will use a non conductive material for the mast.

 

[Paul C]

The J-pole needs to be vertical to match polarization of most stations.

Before you mount it, clean it well with steel wool, then spray it with clear lacquer (Krylon, other paint). Put a couple of coats on it. This helps keep down corrosion of both the antenna and surrounding metal.

The stub on the bottom of the J-pole may be grounded or not. If you are worried about lightning, grounding that stub should help. A direct strike would still kill your receiver.

You can also make a J-pole, for indoor use, from TV twinlead, 450 ohm ladder line, and even a couple of sections of HO "flex track".

Use this calculator on the Hamuniverse site.

http://www.hamuniverse.com/jpole.html

While on the site, explore the various antenna plans.

http://www.hamuniverse.com/antennas.html

Hey! My multiband ham radio antenna is there, too!

http://www.hamuniverse.com/ae5jumultibanddipole.html