After researching and looking at all the possible solutions for a antenna that I either wanted to build or buy for 2 meter and 70cm use, I decided to attempt building a Super J-Pole. I figured the cost of me building on was more economically sound and the experience gained in the process would be priceless. One question I have, is would anyone be interested in seeing me do a step by step tutorial on the build here, or would I be better off just writing a document and then posting it here as a pdf? I also plan on hopefully making a video of the build for my YouTube channel.
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2 Meter - 70cm Super J-Pole
- Thread starter Peter Walker
- Start date
Great idea! A step by step tutorial works a lot better than posting as a PDF 
Of course, you can also put up the link to your video on youtube when that is done.
BTW, this project can qualify you for the spring contest if you get it done in time
Of course, you can also put up the link to your video on youtube when that is done. BTW, this project can qualify you for the spring contest if you get it done in time
When is the contest deadline? I hope to have it finished by Sunday morning, Tuesday afternoon at the latest.
I just built on and got it installed last weekend. Works great! Have a 1.1 to 1.4 match across both bands (2m & 70cm). Got the plans for it here:
Copper Cactus J pole antenna - 2 metter 70 Cm dualband
By the way, I left 1 1/4" between the tuning section between the 57 1/2" and 38" lengths of copper.
It works great!
A good detailed, step by step construction guide would be great, with pictures and video.
Have fun building it, give you a good feeling and helps build your confidence.
Copper Cactus J pole antenna - 2 metter 70 Cm dualband
By the way, I left 1 1/4" between the tuning section between the 57 1/2" and 38" lengths of copper.
It works great!
A good detailed, step by step construction guide would be great, with pictures and video.
Have fun building it, give you a good feeling and helps build your confidence.
Hi Peter, Yes these antennas do work and you'll probably have fun making one.
I have found them to be best made cheaply with wire construction and then used as a camping antenna.
Why? Well they do WORK, but are low gain antennas. If you're wanting to end up with a permanent base antenna for these bands you are going to want one that has much more gain. A commercially built co-phased 5/8 dual band base vertical such as those made by Comet, Diamond and Hustler, like you see at the ham stores or catalogs, are EXPONENTIALLY better performers.
So you need to decided how GOOD of an antenna you want to end up with for permanent home operations.
Good luck with whatever you decide.
I have found them to be best made cheaply with wire construction and then used as a camping antenna.
Why? Well they do WORK, but are low gain antennas. If you're wanting to end up with a permanent base antenna for these bands you are going to want one that has much more gain. A commercially built co-phased 5/8 dual band base vertical such as those made by Comet, Diamond and Hustler, like you see at the ham stores or catalogs, are EXPONENTIALLY better performers.
So you need to decided how GOOD of an antenna you want to end up with for permanent home operations.
Good luck with whatever you decide.
WW is right, kind of depend on what you are planning on doing with it, just hitting a repeater or simplex. The main reason I built mine was my radio room is downstairs in my home and the rubber duck on my HT was not sufficient to hit the repeaters. Now I have no problem hitting many repeaters in my area.
Hey Peter, I built one of these antennas about a year ago and works awsome. I can hit any of the repeaters in the area with no problem. 30+ miles easy. It is a copy of an arrow j-pole. take a look it was a fun build and cost only about 25$ in material. Here's the link: J Pole Antenna . What ever you decide to build have fun.
The one I'm constructing is not like the Arrow Antenna. The one I'm making is what the call a Zeppelin Antenna because its the same design the Germans used during WWII. It can be found Here and Here. I cut out the parts last night and fit it all and I was really surprised at how really easy it all was. In parts only I have about $30 invested and everything I have read about them is all good. I'm really looking forward to getting it hooked up this coming week.
Personally, I think there are some misnomers out there about what these antenna are and can do.
The true copper "cactus" j-pole was so named because it consisted of two j-poles, one for 2-meter and one for 70-cm. The top part of the main element was the 70-cm j-pole and was fed via coax through the main element. It literally looked like a cactus and had some variations including 1.25-meter (tri-band).
The "super" j-pole is a co-phased 1/2-wave over 1/2 wave, and can perform accordingly, but as with all j-pole designs, has an irregular radiation pattern.
Personally, I think these are more trouble than they are worth, unless you make one out of wire twinlead as a portable antenna. That is because you could build a standard 5/8-wave antenna with a similar effort and get slightly better results than with a standard j-pole, which is basically a limited 1/2 wave antenna.
But these are just my opinions gathered over years of research and experimentation.
The true copper "cactus" j-pole was so named because it consisted of two j-poles, one for 2-meter and one for 70-cm. The top part of the main element was the 70-cm j-pole and was fed via coax through the main element. It literally looked like a cactus and had some variations including 1.25-meter (tri-band).
The "super" j-pole is a co-phased 1/2-wave over 1/2 wave, and can perform accordingly, but as with all j-pole designs, has an irregular radiation pattern.
Personally, I think these are more trouble than they are worth, unless you make one out of wire twinlead as a portable antenna. That is because you could build a standard 5/8-wave antenna with a similar effort and get slightly better results than with a standard j-pole, which is basically a limited 1/2 wave antenna.
But these are just my opinions gathered over years of research and experimentation.
I am making some final checks on the antenna that I built and according to my multimeter I'm only measuring 000.4 ohms resistance across the antenna. Is that a good thing or bad thing?
That is potentially a good thing.
The J-pole is a DC grounded antenna and you should measure a direct short.
It is only potentially good because you don't know if the feed (coax) is shorted anywhere else. You could verify by removing one of the conductors from the antenna.
Remember, a DC grounded antenna appears as a direct short at DC, but should look like an ~50 ohm load at the designed RF frequency.
Take a deep breath and key your expensive rig right into that DC short...
BTW, some note better performance on a regular J when the coax center is connected to the short stub, not sure about the super J...
The J-pole is a DC grounded antenna and you should measure a direct short.
It is only potentially good because you don't know if the feed (coax) is shorted anywhere else. You could verify by removing one of the conductors from the antenna.
Remember, a DC grounded antenna appears as a direct short at DC, but should look like an ~50 ohm load at the designed RF frequency.
Take a deep breath and key your expensive rig right into that DC short...
BTW, some note better performance on a regular J when the coax center is connected to the short stub, not sure about the super J...
I'm afraid I'm at a standstill at the moment. Unfortunately I'm having problems figuring out where and how I'm going to mount the antenna. Its too tall for my attic, I put it on a temporary mast on my back deck and it just seemed very unstable the way I had it mounted. I'm going to have to figure something else out. It being copper, I don't want it so low that the thieves in my neighbor hood can take it while I'm gone to work or wherever. If I could mount it just a couple feet from the vertical already on my roof I would be in business.
I originally thought about painting it with grey primer paint but instead sprayed it with Lacquer clear coat. I'm going to have to rethink how I'm going to mount it. That is the main issue right now. I think what I'm going to have to do is extend the bottom mounting stub some way and then water clamp it onto the mounting mast.