Super J Pole

[Spokes]

Looking to have a little play around this weekend with building a few new vertical antennas and stumbled across some info on the super j pole. On the write it it says it has really good gain so I done some research and everyone was raving about them, just wondered if anyone's used them and what the results were like compared to say a properly tuned dipole?
Also any links or suggestions to help along with the build would be welcome the antenna itself is straight forward its the ringo that Im a little concerned about!

[teckniqs]

Albert H very highly rates them for FM broadcast coverage.

[Spokes]

Hopefully the man himself will touch down shortly and help me with the ringo.

[Albert H]

The Super-J works well, but you have to take care with its construction. The original design (for 70cm) used the folded quarter-wave section as part of the structure of the aerial. This will not give sufficient mechanical strength at 3m - I used a fibreglass pole up the middle to give rigidity to the whole thing. It actually works as a colinear and has a sort of doughnut-shaped radiation pattern - very little energy goes either upwards or downwards. It has plenty of useful gain when correctly matched.

Another variant is the MSJ - the "modified Slim-Jim". It's a very narrow bandwidth aerial and takes a lot of effort to get matched, but for a cheap, short aerial with a bit of gain over a dipole and a downward radiation pattern (great for really high sites), it's a viable option.

[shuffy]

IIRC the 5/8 over 5/8 Ringo has a lower angle of radiation than a Super J. Super J is probably easier to make though. Both have way more gain than an MSJ, obviously, but on 3M they're getting a bit on the hefty side.

[Spokes]

They do seem to have some length on em lol

[Albert H]

The ⅝ over ⅝ has got some amazing gain, but it's huge on Band II. Also, the radiation pattern is excellent. I've used them for TV on Band IV and had great results.

[radionortheast]

this is the kind of thing I watch in bed at night, the guy makes a silm jim and strings it up in a tree, pitty the only tree was chopped down here.

interesting part starts at 8 minutes



i made the folded dipole here:



used thick speaker wire, I was getting good swr also a greater bandwidth but then when i put the aerial vertically the swr went up was more than a dipole.

I consider making the silm jim using 450 ohm cable, like in the video. I have a long lenght of thick speaker wire I don’t know the impedence if it could be used, it looks like an easy way to do it using 450 or 300 ohm

[Spokes]

I gave up on the Super J and just went for the traditional J Pole due to the height of the thing. Needed a 6 turn choke over a 4" diameter to get a swr of 1.2 and an impedance of 50ohm at the base of the antenna, gonna slap it on for a test on a 100w rig and see what the coverage is like




Sent from my iPhone using Tapatalk

[teckniqs]

Is that the Sandpiper's 'J-Match' antenna?

[Spokes]

Not too sure to be honest mate, just a normal J I think, just with the choke mounted on the boom so it looks a bit neater on the eye

[teckniqs]

Just had a look and it's not the same. Your J pole has a very professional finish, it's the tidiest I've seen.

[thewisepranker]

Could you take a closer picture of the matching section please? I can't quite make out what's goinf on there and I'm curious to see.

[Spokes]

Haha cheers mate, will inbox you a couple snaps when I get home from work. There's not a great deal going on just some jubilee clips to connect it to the verticals and some wound up coax, also the copper is inside the pvc to make it look more cell site friendly

[thewisepranker]

Cheers for the pictures - it makes sense now. It looked like the coax was connected the wrong way round from your first picture but it clearly isn't.

Very neat.

[teckniqs]

The Super-J antenna:

super J antenna.jpg

[thewisepranker]

...and the Super J-Pole after a 10 MPH wind:

[Spokes]

...and the Super J-Pole after a 10 MPH wind:

[Albert H]

I build the Super-J with a fibreglass rod running up the middle, so that the folded phasing stub doesn't have to take the weight of the upper radiator. I've also built them with two or even three phasing stubs so that they have insane amounts of gain - there's a 70cm repeater in Eastern Europe with a SIX section Super-J!!!

[thewisepranker]

Six sections? That must be guyed, surely?