Anyone using a J-pole antenna???

[ocn29rsc]

I have seen alot of advertiesments for j-pole antennas...and they are a couple different versions on e-bay by different vendors.

I think one of the uhf ones indicated it had 3 or 4.7 db gain while the other one was 3db. So are they any good? What about transmitting do they really have a punch similar to like antenex or maxrad omni directional antenna's?

I'm always looking to try different antenna's for scanning and have even thought about setting up a gmrs base and was hoping someone out there could shed some light on these.

Thanks for the input!

ocn29rsc

 

[blueangel-eric]

I like the Arrow Antennas version. it's professional looking and has great mounting with a regular u-bolt problem with the copper pipe ones is it's compicated to mount like a regular U-bolted antenna.
I have a homebrew clone of the Arrow antenna version and it works great!!!
http://www.arrowantennas.com/
and the same antenna here
http://www.antennawarehouse.com/Amateur/J-pole.htm

 

[prcguy]

A J pole has 0dBD gain unless its a collinear version with stacked elements fed in phase. A J pole is simply a half wave radiator, end fed with a 1/4 wavelength stub to match the very high impedance to 50 ohm coax. Most home made versions will probably work worse than a simple 1/4 wave ground plane made from scrap wire due to mistakes made in dimensions or matching the J pole. The simple 1/4 wave ground plane can be made with a fat vertical element and provide a good match over the entire VHF high band where a J pole will not. Just my 2c.
prcguy

 

[N_Jay]

A J pole has 0dBD gain unless its a collinear version with stacked elements fed in phase. A J pole is simply a half wave radiator, end fed with a 1/4 wavelength stub to match the very high impedance to 50 ohm coax. Most home made versions will probably work worse than a simple 1/4 wave ground plane made from scrap wire due to mistakes made in dimensions or matching the J pole. The simple 1/4 wave ground plane can be made with a fat vertical element and provide a good match over the entire VHF high band where a J pole will not. Just my 2c.
prcguy

Shhhh, you are going to ruin the myth! :lol::twisted::lol:

 

[texasRono]

J-Pole

mabe tomorrow I can get a pic of each but yes, I am using a Jpole---Copper Cactus J-Pole as seen on the net. I also recently made a 1/4 wave groundplane. Comparing both of them at 40 ft. on my tower at the same time I notice a slight, very slight-----improvement on 2 meters with the Jpole but, on 440 the 2M GP always outperforms the JPole. The JPole also interferes with my 10m antenna, cost about $30 and 2 hours more than the ugly little groundplane. The GP was also much easier to sidemount to the tower and could easily be raised to 25-40 ft. with basically nothing. My GP is nothing more than a so-239 socket with solid house wire-stripped at 19 1/4" and soldered to the connector with a short piece of metal pipe for the mounting stub.
Also, raising my JPole from 25' (roof level) to 40' on tower made very little difference, if any. Raising the little groundplane the same really, really made a nice difference, especially on 440.
Hope this helps you, and Im sure someone will shoot me down with the 5/8 wave advantage and all, but it is how it is here---lol
PS...im also using RatShack RG 58 coax....only 50' though, doesnt seem overly lossy....about 60mi on 2 meters and 35mi or so on 5 watt HT in daytime to 90 mi. at night, every night.

 

[blueangel-eric]

mabe tomorrow I can get a pic of each but yes, I am using a Jpole---Copper Cactus J-Pole as seen on the net. I also recently made a 1/4 wave groundplane. Comparing both of them at 40 ft. on my tower at the same time I notice a slight, very slight-----improvement on 2 meters with the Jpole but, on 440 the 2M GP always outperforms the JPole. The JPole also interferes with my 10m antenna, cost about $30 and 2 hours more than the ugly little groundplane. The GP was also much easier to sidemount to the tower and could easily be raised to 25-40 ft. with basically nothing. My GP is nothing more than a so-239 socket with solid house wire-stripped at 19 1/4" and soldered to the connector with a short piece of metal pipe for the mounting stub.
Also, raising my JPole from 25' (roof level) to 40' on tower made very little difference, if any. Raising the little groundplane the same really, really made a nice difference, especially on 440.
Hope this helps you, and Im sure someone will shoot me down with the 5/8 wave advantage and all, but it is how it is here---lol
PS...im also using RatShack RG 58 coax....only 50' though, doesnt seem overly lossy....about 60mi on 2 meters and 35mi or so on 5 watt HT in daytime to 90 mi. at night, every night.

I too see little improvement in a Jpole over a groundplane or dipole. they're big, ugly, and hard to mount. that's all they're good for. Except for my precious Arrow Antenna look alike. not sure on the gain though. since i've moved to a new location it's kind of hard to tell how good it is without mounting other antennas in the same spot for comparison. like the ARX2B.

 

[DaveH]

Shhhh, you are going to ruin the myth! :lol::twisted::lol:

Enjay, perhaps (besides the nudge-nudge wink-wink) you could fill us in on
exactly what the myth is?

BTW I re-re-nominate you for the "Over-use of Emoticons Award" ! (GBGL)

Dave

 

[nd5y]

The myth is that j-poles have lots of gain and are better than anything else.
A j-pole is just a 1/2 wave end fed antenna fed with a 1/4 wave transmission line matching section.
If constructed and tuned properly, they only have as much gain (0 dBd) as a dipole.

 

[zz0468]

Anyone using a J-pole antenna???

No. Some of us know better.

 

[rfradioconsult]

J poles work great only if they are coated with special RF attracting paint; however, you need to use the specific color coded shade for your band of interest. If you are planning on multi-band operation you can use the VHF white and the UHF red. The colors should be applied in a spiral configuration; the result will look like a barber's pole.

 

[blueangel-eric]

J poles work great only if they are coated with special RF attracting paint; however, you need to use the specific color coded shade for your band of interest. If you are planning on multi-band operation you can use the VHF white and the UHF red. The colors should be applied in a spiral configuration; the result will look like a barber's pole.

smart mouth :roll:

 

[Don_Burke]

I have seen alot of advertiesments for j-pole antennas...and they are a couple different versions on e-bay by different vendors.

I think one of the uhf ones indicated it had 3 or 4.7 db gain while the other one was 3db. So are they any good? What about transmitting do they really have a punch similar to like antenex or maxrad omni directional antenna's?

I'm always looking to try different antenna's for scanning and have even thought about setting up a gmrs base and was hoping someone out there could shed some light on these.

Thanks for the input!

ocn29rsc

I use several homebrew J poles and I like them.

The gain numbers are inflated like they are for most antennas. There may be a little advantage over a dipole as the stub has to radiate a bit, although I have not seen it.

One big advantage is that a J pole is inherently DC grounded. It can also be made brutally strong.

The downside for most users is that they can be pretty narrow banded, which is actually an advantage in some applications.

If one type of antenna was the best for all uses, there would only be one type of antenna in use.

 

[DaveH]

Count on some people to exaggerte or over-dramatize the misconceptions
we are all supposedly under. I know the J antenna is an end-fed 1/2 wave
and don't expect miraculous gain over a ground plane. Good old ground
planes are great, and I use them, but also like the J's lack of radials and
dc grounding. Fun to make out of copper pipe, at least until the price of
copper jumped about six times. Once I made a VHF one from aluminum tube
sections cut from an old CB antenna (can't think of a better re-use of the
latter).

LB Cebik's website has some good articles like "J-poles I have known".
Unfortunately he passed away earlier this year.

Dave

 

[wwhitby]

I compared both a homebuilt J-pole to the Radio Shack 20-176 1/4 wave. My totally unscientific test consisted of comparing which antenna received local railroad defect detectors the best using the same scanner and cable and mounted at the same height.

The received signal on the 20-176 was always stronger then the signal I got using the j-pole. Since then, i've stopped using j-poles entirely.

Warren

 

[blueangel-eric]

I compared both a homebuilt J-pole to the Radio Shack 20-176 1/4 wave. My totally unscientific test consisted of comparing which antenna received local railroad defect detectors the best using the same scanner and cable and mounted at the same height.

The received signal on the 20-176 was always stronger then the signal I got using the j-pole. Since then, i've stopped using j-poles entirely.

Warren

you didn't specify that freq the Jpole was tuned for. Was it tuned for 2m or RRband?

 

[wwhitby]

you didn't specify that freq the Jpole was tuned for. Was it tuned for 2m or RRband?

RR band. IIRC, I cut it for 161Mhz.

 

[rankin39]

Go to: http://www.andersonrepeaterclub.org/pdf/J Pole Antenna.pdf for easy plans for an inexpensive dual-band J-pole antenna that works well.

Bob, WoNXN

 

[blueangel-eric]

Go to: http://www.andersonrepeaterclub.org/pdf/J Pole Antenna.pdf for easy plans for an inexpensive dual-band J-pole antenna that works well.

Bob, WoNXN

those twinlead jpoles are very narrow banded and don't work well for scanning. i made a 2meter jpole and on the RR band it was no better then a typical portable antenna on my ham radio. A real jpole is more broadbanded. I am using my Arrow antenna style Jpole on my base scanner at the moment and i notice no difference from it and my Scantenna except the RR hotbox detectors come in better since its higher up.

 

[thomast77]

Anyone tried the Vertical Bazooka? 2 Meter Vertical Bazooka - Build A Vertical Bazooka from Coaxial Cable by VE3VDC
I am wondering how well it stacks up against the Jpole and others mentioned in this Thread? I am thinking about building one since it is cheap requires no so-239 and no connectors except on the radio end. in is essentially built into the coax. I will be cutting it for 155mhz and using it on my scanner. I monitor mainly in the 155mhz and 453-460mhz range. Any thoughts?

 

[prcguy]

The J-pole is an end fed 1/2 wave and the misnamed Bazooka (coaxial dipole) is a center fed 1/2 wave. They will work the same and are both a single band antenna. You might get more bandwidth from the coaxial dipole if you use fat pipe or tubing for the elements.
prcguy

Anyone tried the Vertical Bazooka? 2 Meter Vertical Bazooka - Build A Vertical Bazooka from Coaxial Cable by VE3VDC
I am wondering how well it stacks up against the Jpole and others mentioned in this Thread? I am thinking about building one since it is cheap requires no so-239 and no connectors except on the radio end. in is essentially built into the coax. I will be cutting it for 155mhz and using it on my scanner. I monitor mainly in the 155mhz and 453-460mhz range. Any thoughts?