NT1K – Welcome

Open Stub J-Pole Project – Completed (Many times)

by on Jan.03, 2011, under Projects, Uncategorized

I’ve constructed a 144/440 Dual band Open Stub J-Pole Antenna.

Assembled Open Stub J-Pole

I saw the plans for this on the internet (link to plans) by Allen Lowe (N0IMW). Since I had a Metal Fabrication backround I thought this would be an easy build.

Plans for Dual Band J-Pole 1

Plans for Dual Band J-Pole 2

I understand that everyone else in the world uses Metric, You can convert these numbers to MM and use 10mm aluminum rod and thread for the elements.
However I am not sure about the SO-239 adapter. I’ve read that it can be difficult to obtain the adapter in Europe.  Any EU/Metric users, please help me out and give me details on what you did.

 

I did some minor changes from the above. Instead of using nuts I used pressed “PEM” nut on the underside and used thread protecting vinyl caps on the tips

Aluminum J-Pole Base 2nd View

Here are some SWR Shots. I don’t have state of the art equipment so this will do for now

Testing the SWR on 440Mhz

Testing the SWR on 146Mhz

It was a really fun and quick build. Plus it works okay. It’s no Diamond X510. What else do you expect for around $20 in parts? I love it.

If for whatever reason you can not build this. It is manufactured by the designer of this antenna and has them for sale on his website for a reasonable price. So check out ARROWANTENNAS.COM for the OSJ and other quality crafted antennas.

Due to many e-mails, I just want to state that I do not and will not manufacture these antennas for sale. I think those sold at Arrow Antennas are well worth price.

EDIT (5/2/11): I’ve Also built a “Adjustable” version of the Open Stub ( OSJ ) J-Pole as seen HERE.

EDIT (10/20/2011): Someone let me use a MFJ Antenna analyzer so here is a reading from the VHF side of the Antenna.

@ 145.98Mhz I got a reading of 1.0SWR with a 51ohm impedance. The antenna was resting on a wooden chair so I am not sure what the value would be when fully installed but I don’t think it would change that much since it doesn’t need grounding.

Update 3/7/2014

Here is another reading on the VHF side of the antenna

NT1K-Jpole

NT1K-Jpole-page-001

 

Update 6/17/2014

Thanks to Jon (KI6RT), he provided some SWR plots from the VNA. What’s great is that he measured the UHF side of the antenna which I’m un-able to measure with the equipment I have.

JPOL144

VHF

 

JPOL440

UHF Side.

 

 

 

:, , , , , , , ,

8 Comments for this entry

  • Casey

    Wonderful build was able to hit many repeaters with it attached to a pole stuck in a sleave in my front yard. Can’t wait until I get it up on the roof.

    Thanks

  • Don

    thanks for the antenna plans and your contributions.

  • Marcos

    Wonderful work!
    Thanks.
    73 from Spain,Europe

  • Dr.Odat

    Hello there….
    Can I use a (10 millimeter) aluminum rod instead of [3/8"(9.5 millimeter)]….????
    and if there is a very minimal variation in the length will that affect the efficiency of the antenna???
    Thanks a lot.

  • Steve

    I purchased one of these from my local LDS HAM guy, works wonders.

    I was wondering if the antenna poles could be covered with electrical tape or any other kind of tape for camouflage?

  • Jeremiah-KC0IJY

    I am currently looking to build this antenna but have run into a problem locating the aluminum rod in the length needed. I live in Toledo, Ohio if anyone has any idea where I can locate it please post in the comments. BTW. Home Depot does not sell it in 8 ft long pieces.

  • David KC9JWO

    Take two smaller pieces, using a die cut threads on it and use a coupler nut. This can also help in any adjustments.

  • jeff

    i would like to have one just like a arrow antenna but collinear i think it would work grate i have no skills as far as antenna building so i am not even going to try lol

4 Trackbacks / Pingbacks for this entry

Leave a Reply

Looking for something?

Use the form below to search the site:

Still not finding what you're looking for? Drop a comment on a post or contact us so we can take care of it!