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J-Pole Antenna

I agree with that and is why when I went to building a 2m vertical omni, I figured my time was best spent on a classic 5/8 ground plane...I still love the concept of the j-pole though.
 
It finally dawns on me that this has come down to arguing the benefits between a 1/4, 1/2 and 5/8 wave antenna, each of which has benefits in certain conditions/situations. It doesn't say anything about the builder's particular requirements, or his initiative in building an antenna, or trying to find the reason it isn't behaving as expected. It's just the same old argument about the 'size' of the antenna in use.
Jaymon, I'm glad you got it fixed.
- 'Doc
 
W5LZ said:
It finally dawns on me that this has come down to arguing the benefits between a 1/4, 1/2 and 5/8 wave antenna, each of which has benefits in certain conditions/situations. It doesn't say anything about the builder's particular requirements, or his initiative in building an antenna, or trying to find the reason it isn't behaving as expected. It's just the same old argument about the 'size' of the antenna in use.
Jaymon, I'm glad you got it fixed.
- 'Doc
Click to expand...

Doc, you know any discussion about antennas or amplifiers always ends up in a "mine's bigger than yours" pissing contest. :laugh:
 
Capt....The SWR meter is a SWAN Electronics SWR-1. The upper limit is 100 watts. I live in Ocala, FL. and while operating thru the Gainsville repeater which is 35 miles north of me I got excellent reports from operators north of Gainsville. I'm not changing anything.

Harold
 
Channel Jumper said:
Someone here isn't comparing apples to apples.
I am talking about a 2 meters / 440 antenna and you are talking about a HF antenna.
You show me a home brew antenna that will talk on 2 meters / 440 the whole way to "Ireland, England, Hawaii, Italy. New Zealand, Australia/Tasmania, across Canada, The West Coast, Jamaica, Bermuda, Virgin Islands, Puerto Rico, and other points on the globe" and I will eat my words and my Yaesu 8900 - mounting bracket and all.
Click to expand...

It is the same thing.You were talking about homebrewing versus laying down the cash for an antenna. The band is irrelevant.

The other comment was the hurricaine Katrina comment.
If there is no infrastructure and no repeaters working - who are you going to talk to with a hand held or a 2 meters radio when the range is line of sight?
The radio might talk 40 miles simplex.

That is the point that I am trying to make.
Click to expand...
And 40 miles is more than enough to connect you with the local emergency operations center in about 99% of the cases. Back in 1998 I was involved with the recovery operations after the crash of Swissair flight 111. It was in an area where due to an anomaly in the topography the RCMP could not access their repeater. It was a dead zone. There was also no cellular coverage. Amateurs set up at the mobile commend center and had other amateurs located at the detachment in Tantallon. For three days until Aliant Telecom was able to provide a mobile cell site extender a lot of emergency traffic was relayed by both simplex and via the amateur repeater which due to being located in a different area actually had coverage back to the detachment.We were able to communicate directly with the naval and coast guard ships as well as military search aircraft that actually operated on simplex inside the 2m band. First responders were amazed at what our 2m HT's and mobile radios would do even on simplex. This situation was not really much different than the requirements after Katrina except in the amount of traffic.

With a good antenna - you can talk farther, especially if you get some height above everything else in the neighborhood.
The second thing is - that your signals will be blocked by your neighbors houses and trees and stuff when it is next to the ground.
That is just basic reception 101 stuff here and not rocket science.

The HF - it doesn't matter how close or far away from the ground you are with the transmit / receive antenna.
Click to expand...
I don't even want to comment on that false statement but I will. Here is the comparison, an HF antenna installed low to the ground will perform MUCH worse than if installed higher. That is a fact. A homebrew antenna may perform just as well as a comparable commercially manufactured antenna. That is also a fact.You seem to think that it doesn't matter how high an HF antenna is mounted and that it's not OK to hombrew a basic VHF antenna as your first antenna because it is a poor performer.

Are you sure you are actually an RF engineer? :whistle:
 
W5LZ said:
It finally dawns on me that this has come down to arguing the benefits between a 1/4, 1/2 and 5/8 wave antenna, each of which has benefits in certain conditions/situations. It doesn't say anything about the builder's particular requirements, or his initiative in building an antenna, or trying to find the reason it isn't behaving as expected. It's just the same old argument about the 'size' of the antenna in use.
Jaymon, I'm glad you got it fixed.
- 'Doc
Click to expand...

It finally dawns on me that any antenna discussion ends up in one pissing on another...

So what?

BTW, you guys have already done a great job giving the help that was needed, so why bother?

At any rate, one usually starts out building something, then something else, and finally something, hopefully, better.

I think the best "one" can ever hope to do is encourage another to keep going.

I've had the most success with a dipole, not because of performance.

The J-pole was interesting - I like the portable ones built from twin-lead...

I really like the 5/8-wave groundplanes...they seem to provide the best general performance.

Yagis are great, for their application.

Biquads and such are better still...

Today, I just would not fiddle with a j-pole any longer. I've graduated!

now, don't forget to lift the seat!
 
Channel Jumper said:
I am talking about a 2 meters / 440 antenna...
You show me a home brew antenna that will talk on 2 meters / 440 the whole way
Click to expand...

Your best bet is a simple dipole. It should load up just fine on both bands.

Let me throw this in there...

A genuine "cactus" j-pole will work too, but good luck with that.

A true cactus j-pole is a 2-meter j-pole with a second 440 j-pole fed on its tip. they do work, but IMO, not any better than a simple dipole...
 
... and just for grins.
A typical 2 meter 'J'-pole will work just fine on 70 cm too. I have a combination 2 meter and 70 cm 'J'-pole and can't tell any differences between it an just a plain 2 meter 'J'-pole. Both are sort of high in SWR on 70 cm, which really isn't that big'a deal. I can't say that always hold true, but it certainly isn't all that rare either.
- 'Doc
 
The J-pole is a good learning experience.

If you want something that works a little better consider colinear vertical antennas. All you need id an insulator and an delay line like a hairpin.

Look at some of the VHF Ringos for an idea.
 
Kamikaze said:
The J-pole is a good learning experience.

If you want something that works a little better consider colinear vertical antennas. All you need id an insulator and an delay line like a hairpin.

Look at some of the VHF Ringos for an idea.
Click to expand...


Or the extended J-Pole which is a co-linear vertical with a hairpin phasing stub.

~ J-POLE DOUBLE HEADER ~
 
J-Poles

Hello Friends..
I build J-Poles and sell them at Hamfest. In the past year I have made and sold about 50 to 60 units.

The fellow who made the original post was having a SWR problem.

Hear is my recomendation.

I use 1/2 inch copper water pipe,. a good quality SO-239 connector and place a brass tuning screw on the top of the dirve element 2 inches long.
If you place the 239 connector 2 3/4 inches above the center of the tee connection... then solder the center wire to the short element at the same distance a low SWR should be found by adjusting the brass screw.
My J-Poles tune 1.4 or less at 146.520. Usually less...much less.!

The website he listed and used for the build is a good one. My units are very close to that design.

BTW...There is nothing more fun than making a contact on something you built yourself.:tt1:
 
Hello Jim,

Right now my J Pole is working perfectly and using 25 watts I get to all the mid Florida repeaters that im interested in. The 30th of April I will be going to the Gainesville Amateur Radio hamfest. I have already registered to take my General exam while i'm there.
Your mention of a brass tuning screw really got my attention. I wish I could see a picture of what your talking about. I have had a lot of fun experimenting with my J Pole. I live in a RV park and space is just about zero. It a vertical or its nothing. I cant even put up a Yagi antenna.
Thanks for the post and continue enjoying our hobby.

EDIT: I found what your talking about.... http://kb8ojh.net/antennas/jpole.html

Harold
 
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