The j-pole antenna is fixed...

I applaud John and his hard work, he certainly has something useful here. But with so many available antenna choices & designs for VHF/UHF etc., and with all of them working quite well for most purposes, I must ask - is it worth the trouble?. I can build or buy a good 5/8-wave collinear antenna and likely not have to worry about patent issues. Ditto a quarter or half wave ground-plane antenna. On my tower now is an old Hy-Gain V2r collinear and it works wonders .

 

Clearly there are needs where the 'antenna' needs to look like something else. That is one option for these designs. I am sure there are others.

 

@KX4O, Congratulations! I just looked over your patent, and that is indeed an exceedingly thorough job of it, especially as you said all the prior art! (I have several myself so I appreciate the work you put in on the patent, and of course on the invention).

 

My favorite benefit of this Mast Mountable J is the stout grounding and dead short coax center to shield it provides while still being an antenna at the design frequency. It's another choice in the tool bag.

For my current QTH purposes the J didn't survive my trade study. My rooftop antenna is the Diamond CP22E. Not as robust as plumbing pipe, but I like 5 dBi. Review here in case anyone has time to kill. Viva la choice.

By the way everyone... one of the nice finds during all this research is the positive utility of the roll up J antennas. Thus configured the single band variations have no conductive mounting structure to worry about. Measurements confirm the ferrite, for VHF at least, chokes the common mode feed line RF currents quite well or at least good enough to make a positive difference - The ferrite or equivalent choke mechanism on the transmission line is required. This yields an end-fed vertical dipole with a free space gain figure of just over 2 dBi wherever you can hang it. Nice!

 

Dean Wormer is a good, but wouldn't a guy from Animal House prefer MISSES Dean Wormer?

Both great Movies: But this one is what I was thinking.... very Apropos.

Erika DD

 

I had a pocket J-pole I built back in 1980, out of home grade twin-lead. That antenna worked great, had about 10dB of gain over an IC-2AT rubber duck antenna. Worked well for years.

I built a J-pole variant about 10 years ago, and it worked well, too. It consisted of a QW coaxial stub instead of the usual open wire stub. The stub was around 12" long for 2M, shorted at the bottom, and fed about 1.25" up from the bottom with coax. The antenna was around 39" of wire attached to the top center of the stub. I hung the antenna from the inside 9' ceiling for testing, and it worked very well, at least as good as any other HW antenna. That antenna would be easy to build and mount inside a 3/4" PVC pipe, with a ferrite placed at the feed point.

 

Ahhhh!

Yep.

Thanks Erika

Stay well

73
Chip W1YW

 

I also made one of those roll up j-poles, with the thin translucent TV twin lead, back in the early 90’s. I still have it and it works well - that is, much better than a rubber duck.

 

In the defense of the "I've seen parts of this before" The shorting stub to reflect an open is discussed in
Nov 2004 - QST (Pg. 61)Experiment #22--Stubs, is a source,

as well as https://maritime.org/doc/#elect (Module 18 page 2-21 or so).

It's a little more complicated, but on radars the quarter wave stub has been used for many years.

It is a novel use in this J-pole instance.

Thanks
Joel

 

Ahem, Chip... From your previous post:

"Comments have consequences. Let's use good judgement in making them."

 

Exactly. The very best of judgement. Backed by 65 years of experience on the matter.

Ask him about his deleted posts on Jewish business leaders.

Ask if that call was ASSIGNED to him by the FCC, or whether he specifically requested it.

Ask why those posts were deleted.

Again, I think it's peachy cool that the FBI owns this antenna, and is likely monitoring the various posts. FB with me.

73
Chip W1YW

 

Cactus Antenna !

 

Typical Lib Run University

 

Replying to myself, I reject my previous post. After reading the patent history of John Huggin's patent application, I note that it was initially rejected by the USPTO. Also, I note that in the details of the patent, a lot of prior art is referenced. The patent seems to stand on the assertions that combinations of the details of prior art designs do not exist. For example, designs with decoupling stubs lack the direct path to ground for current from lightning, and other designs do not include feedline inside the mast while incorporating a decoupling stub, etc. There are many combinations of prior art that have to be considered.

Also, the applicant's employment with the FBI mean that US Government entities may use the patent without payment.

Ted, KX4OM

 

What would be the problem with that? You know they wont be charging folks for using that data....