New antenna build

[King18471]

I’m considering building an antenna for my base station 2m/ 70cm radio putting out a max of 50 watts. It will be used for basic simplex and repeater work. Would you suggest a dipole or J pole antenna and why? If neither of these, then what? Thank you. 73.

 

[majoco]

Proper J-poles built as per the original article or a 'slim jim' work well for a single frequency band. Google for "G2BCX J-Pole" to get the real McCoy - ignore all those made out of copper pipe with a stub out the bottom to mount on the mast.
Mine is shown here - has worked very well over thirty years with only the occasional bit of maintenance.


https://forums.radioreference.com/a...d-vs-gable-maximum-mast-size-slim-jim-sml.jpg

 

[WA8ZTZ]

I’m considering building an antenna for my base station 2m/ 70cm radio putting out a max of 50 watts. It will be used for basic simplex and repeater work. Would you suggest a dipole or J pole antenna and why? If neither of these, then what? Thank you. 73.

If you are planning on using a dipole, you want to mount it vertically. 2m/440 FM work is all vertical polarized.

 

[RogueSteward]

Proper J-poles built as per the original article or a 'slim jim' work well for a single frequency band. Google for "G2BCX J-Pole" to get the real McCoy - ignore all those made out of copper pipe with a stub out the bottom to mount on the mast.
Mine is shown here - has worked very well over thirty years with only the occasional bit of maintenance.


https://forums.radioreference.com/a...d-vs-gable-maximum-mast-size-slim-jim-sml.jpg

That is a nice antenna! I want to do something similar. What material did you use for the element?

 

[bb911]

I’m considering building an antenna for my base station 2m/ 70cm radio putting out a max of 50 watts. It will be used for basic simplex and repeater work. Would you suggest a dipole or J pole antenna and why? If neither of these, then what? Thank you. 73.

You can Google " Ed Fong j antenna", also. Suppose to be best for the $$. Some say that he's the originator of the j antenna in a pvc tube.

I used a home brew 2m J antenna built from copper piping for numerous years (scanner and 2m only) and it worked great. Made a great wide band scanner antenna.

 

[bb911]

PS - I didn't even have to tune it. Must have gotten lucky?

Ooops. This was meant to be an edit to the above post.

 

[jim202]

Proper J-poles built as per the original article or a 'slim jim' work well for a single frequency band. Google for "G2BCX J-Pole" to get the real McCoy - ignore all those made out of copper pipe with a stub out the bottom to mount on the mast.

Can you explain why you are saying to ignore all the J-Poles made out of copper pipe?

Most of the ones I know in service are made out of copper pipe and function very well. Trying to make them out of aluminum, can be a challenge to keep the oxidation down between the different pieces. Once the oxidation starts, it will effect the operation of the antenna. You don't have this problem with a copper constructed antenna. All the joints are soldered and that insures a good connection between the different parts.

 

[TheSpaceMann]

Build simple ground planes! Easy and inexpensive, and the performance is similar to a J-Pole.

 

[majoco]

The white tube is 32mm waste pipe - the 8mm aluminium elements are on the outside and retained by short lengths of 18mm pipe that go through the main vertical - the top and bottom joints are solid ali cylinders about 8mm diameter drilled and tapped and the vertical elements drilled to take the screws - the coax is secured with solder tags under screws drilled and tapped into the verticals - a PL259 female is on a short piece of coax and the coax the shack fitted into it - the plug and socket are pushed up into the bottom of the pipe - all the holes were sealed with silicon - the top cap is an old film can siliconed in - the ali was passivated and the whole lot painted 2 coats white which is coming off the waste pipe a bit but still good on the ali.

 

[majoco]

Now lets not start this all over again, it's already been thrashed to death. Read.....


https://forums.radioreference.com/amateur-radio-antennas/359846-2-meter-j-pole.html

https://forums.radioreference.com/a...797-collinear-1-4-wave-gp-j-pole-arrow-2.html

 

[bb911]

You can Google " Ed Fong j antenna", also...

Not quite yet bedtime.

"Biography - Ed Fong was first licensed in 1968 as WN6IQN. He later upgraded to Extra Class with his present call of WB6IQN. He obtained the BSEE and MSEE degrees from the Univ. of California at Berkeley and his Ph.D. from the Univ. of San Francisco. A Senior Member of the IEEE, he has 12 patents and over 40 published papers and books in the area of communications and integrated circuit design. Presently, he is employed by the University of California (previously at Berkeley and presently at Santa Cruz- Silicon Valley) as an instructor teaching graduate classes in RF design and High Speed interface design. During his 30 year career he has performed worked for Motorola, National Semiconductor, Phillips Semiconductor and Advanced Micro Devices."

Source: https://edsantennas.weebly.com/about.html

Also: https://www.eham.net/reviews/detail/6377

http://www.qsl.net/sterling/Activities/20170301_J-Pole_Build/Emergency_antennas.pdf