2 Meter J-Pole
Classic Copper Cactus
For my 2 meter FM station I needed an antenna. When I bought my Kenwood TM-281 I was on a strict budget and while I didn't want to compromise on the ariel I didn't have ready cash to buy a $300.00 vertical either. I used the 'Copper Cactus' in teh past as an indoor antenna for my HT and got reasonable results so I deceided to use it as a starter antenna.
Two years later it's still up and it still works great. Attached are the plans I used to construct the antenna
I started with a design I found on the web originally posted by W6MHE and modified it slightly. I will link to the original article at the bottom of the article.
For those that have never built an antenna before this one is pretty easy. If you can turn on a torch and use either a hacksaw or a tubing cutter you can do this!
Supplies for this project are small: (1) 10'piece of 1/2" copper water line, (1) 1/2" elbow, (1) 1/2" tee, (3) 1/2" caps, solder and flux, and two hose clamps.
The tools needed are very basic and you probably have them or can borrow them: Either a tubing cutter or hacksaw, a propane torch, a piece of scotchbrite, and a screwdriver.
So let's start by precutting the pieces of tubing you will need:
- (1) 60" piece. This is the long radiating element.
- (1) 20" piece. This is the short radiating element.
- (1) 1 1/8" piece. This piece connects the two elements.
- (1) 3" (to 4") piece. This is the mounting stub.
I cleaned the outside ends of the pieces that were just cut with scotch brite. This will help the solder adhere and make a good connection. I cleaned the inside of the elbow and tee for the same reason.
I layed out the pieces as shown in the drawing below and then started to assemble the antenna. I used flux at every joint and assembled the entire antenna before I started soldering so that everything was aligned but also to make sure it fit.
Once everything was soldered togther (and cool) I used a couple of clamps to hang my antenna on one of our clothesline poles and attached the coax about 2 1/2" above the cross bar as shown in the picture below. I attached the center conductor to the short radiator and the ground from the coax to the long radiator using hose clamps. I didn't get a good connection the first time so I cleaned everything wth a scotchbrite pad and tried again.
It took only a few adjustments to get the SWR acceptable on most of the 2 meter band so it met my needs. I sealed up the hose clamps with Vulcowrap and added a layer of electrical tape for good measure
The original article can be here.