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J-pole antenna

John James

John James

"Wash your hands!"
Subscriber
Let me start by saying that I am in a "FM-FREE HOLE". Very bad reception of very few stations. I googled "j-pole antenna plans" and got pages of links. Mostly they all were pretty much the same. I ended up going to Lowes and buying some 1/2 inch copper pipe and a couple of 90 degree elbows. I soldered these into a simple "J" shape. I didn't need or want the downtube portion as the antenna is mounted in a stairwell inside the house, fastened with zip-ties. After a little tuning, (as described in the plans), cranked up my tuner, hit the auto search function and let the tuner "do the walking". I'm happy to report that I now get all of the stations that www.radiolocator.com says are in my area, and they are all clear. Even the ones with RDS now display that info. That has never happened before. I spent approx. $15.00 in pipe, fittings, and wire to reach my reciever. I now have a tuner that I will enjoy listening to as opposed to just taking up space in my system. I hope someone else may find this helpful.:music:
 
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There are a gizillion links. Which one(s) did you find most helpful. A lot of these are for HAM bands.
Any pics of the one you built?
 
http://latham.dropbear.id.au/antenna/

I did not use the plate at the bottom. I just soldered two elbows (90 degrees) to a 3 inch (+,-) piece to connecet the 89" upright to the 33" upright. Then you try different locations up and down on the two uprights with the two leads to the reciever to find the best reception. I was able to tune in the house watching the signal strength meter and then put the antenna in the final location. I drilled 2 pilot holes and used 2 SS screws (2) to make the final connection for the leads.
Sorry, no pics. Feel free to ask if you have questions.
 
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Looks nice and simple. But I am hesitant to put a 7 foot long copper rod on my rooftop and connect it to anything in my house. Seems to me this is also a good lightning rod! Is there any good series device to stop a direct hit to this beast? In my work we would put a "polyphaser" at the entry to the building. Is there anything like that that wouldn't bugger up the broadcast bands or attenuate too much but still let me sleep at night???
 
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That is definately a concern. I live in Southern California and we have very little lightning. Perhaps someone will chime in with protection ideas, though I suppose there is only so much one can do. Lightning will do what ever it wants. I have heard of people placing them in stairways or hidden in corners and still getting decent results
 
Get something like this. Connect it to very heavy gauge copper wire and bond to copper lightning rod(s).
http://www.iceradioproducts.com/impulse1.html#1
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I used something similar on a pirate FM antenna which was very big and vertically oriented.:nono:
Get the VHF/UHF version.

Anyone giving advice about lightning protection should say "nothing is perfect" and the best thing is to disconnect in a lightning storm grounding directly. There's load of stuff online about lightning protection. Remember, none of this is worse than putting up an old fashioned TV antenna.
 
I have mine inside the house in a stairwell just to avoid lightning problems. Maybe not the absolute best for reception, but I would rather make it through thunder storms intact! :yes:
 
John James said:
I have mine inside the house in a stairwell just to avoid lightning problems. Maybe not the absolute best for reception, but I would rather make it through thunder storms intact! :yes:
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It seems like yours is working great!
I live in an apt., so if I make this ant. it will be have to be indoors as well.

Having said that, NOTHING beats an outdoor antenna.

Remember when everybody had TV antennas on their rooftops?
 
Try the Fanfair dipole,you can get one from C.Crain co. for around $100.00 and they really pull in some DX FM.I lived in a part of Rocklin that had terrable FM and couldn't get Hearts of Space out of Davis or Chico.I picked up 13 DB just by adding this ANT.
If this dosent do it get an older FM beam from radio shack and a rotor.
 
The one above, the hamuniverse link, is good. You just enter 98 mhz as your center frequency in the calculator.

The the bottom stub on that one, or the metal plate on the other one, can be grounded or not, just does not matter a bit. I know, that goes against all common sense. You would think it being grounded it would "short out" the antenna. No, it doesn't.

I have a 2 meter (144-147 mhz) stainless steel J-pole I'm running right now on my ham rig that really receives and transmits well. I can easily hit a repeater 45 miles away with only 8 watts, though I am told my sound is a little "crackly". Turning power up to 12 watts cleans it up well.

J-poles are also popular for the 6 meter band (50-54 mhz). I'm not at all surprised at John's excellent results.
 
Been considering putting one of these together, too. Thanks for the links, a bit clearer than the ones I stumbled upon.

Used indoors, can twin-lead be used as feeder, or does it need to be coax?
 
I built my jpole for our weekend hideaway in the local mountains and it works well, I use a Magnum Dynalab whip at home, basically the same as the Fanfare. It gives me good results but for the price I am not sure I would do it again. I think a real beam antenna is best but the advantage with the Fanfare is it it EASY to install and can go just about anywhere. YMMV

I will add one thing, I have a friend that lives in the hills of North San Diego County and could only get poor at best FM with an indoor antenna and also had to deal with a cranky HOA so an outdoor antenna was not going to happen easily. I suggested the Dynalab antenna which he mounted to his chimney and has gotten excellent results. Best of all the HOA never noticed.
 
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Let me start by saying that I am in a "FM-FREE HOLE".

I'm just curious as to what the originator of this was using for antenna before. Since the J-pole does not provide any sort of gain, it seems it would have been just as simple to take the ususal supplied folded dipole and orient it vertically to be the same as the J-Pole and do a comparison. I cannot see how the two would perform any differently since they would both be vertical half wave dipoles. The advantage for the J-Pole would be to use coax feedline. But, the Folded Dipole could also use coax by inserting a 4:1 transformer in the line.
Where's the benefit here?
 
NikkoUser said:
HTML: 
Let me start by saying that I am in a "FM-FREE HOLE".

... Since the J-pole does not provide any sort of gain, it seems it would have been just as simple to take the ususal supplied folded dipole and orient it vertically to be the same as the J-Pole and do a comparison. I cannot see how the two would perform any differently since they would both be vertical half wave dipoles. The advantage for the J-Pole would be to use coax feedline. But, the Folded Dipole could also use coax by inserting a 4:1 transformer in the line.
Where's the benefit here?
Click to expand...

I've wondered the same thing. Finally I concluded that the J-pole could be stuck outside and remain relatively inconspicous, and it would be more weather-resistant than a regular cheapy folded dipole. A folded dipole outside is better than a folded dipole inside, other than that though I agree, it would be the same.

For me, it was easier just to stick a square loop inside the attic, than to build the J-pole and mount it outside...
 
I was using the little "twin-lead" wire thingy that came with the tuner. It looks like the old TV antenna wire. I tried turning it every which way, including vertical. No joy! Now I get all the stations in my area with a strong signal. Not only that, I got the satisfaction of building it myself. I don't pretend to know much of anything about antennas or electronics, but this worked very well for me. :yes: :music:
 
NikkoUser said:
HTML: 
Let me start by saying that I am in a "FM-FREE HOLE".

I'm just curious as to what the originator of this was using for antenna before. Since the J-pole does not provide any sort of gain, it seems it would have been just as simple to take the ususal supplied folded dipole and orient it vertically to be the same as the J-Pole and do a comparison. I cannot see how the two would perform any differently since they would both be vertical half wave dipoles. The advantage for the J-Pole would be to use coax feedline. But, the Folded Dipole could also use coax by inserting a 4:1 transformer in the line.
Where's the benefit here?
Click to expand...

Nice thread.

I have done this as my first set up was a cheapy factory issue dipole mounted in the attic, then a J-pole in the attic in a similiar location. The j-pole blows it away. The benefit was/is stronger signal, clearer sound, greater dx'ing, more fidelity to the sound. Why? I don't know.

I think I read somewhere (please correct me if I am wrong) that since the J-pole is omini-directional, that it could be mounted sideways? This may open up some installation possibilities (for someone who does not want the antenna sticking up to high).

I have a home brew J-pole for over a year now mounted in the attic of my house and am very happy with it. Mine is made out of scrap 3/4 inch copper pipe. YD
 
The j pole is not a folded dipole so it is longer (unfolded) and yet is resonant for the frequencies you want. So it is a better receiving antena as it captures more radio waves. One could do the same thing with an antenna tuner and a random piece of wire of shorter and longer length. The longer would be a better receiver as long as the chosen length did not present too high an impedance to the tuner. (I think this is so).

F
 
The J-pole is a 1/4 wavelength transmission line connected to a 1/2 wavelength dipole. The transmission line part does not receive or radiate, only the dipole, same as a folded dipole.
The dipole part does not have to be vertical either.
 
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