Monday, April 24, 2017

J Pole Antenna Design Calculator by K4ABT

J Pole Antenna Calculator by K4ABT
(http://www.hamuniverse.com/jpole.html).
Author:  G.E. "Buck" Rogers, Sr. (K4ABT).
Accessed on 25 April 2017, 04:55 hrs, UTC.
Please click link to read the full article.

Comment:

Thanks to G.E. "Buck" Rogers, Sr (K4ABT) for this ultra simple, easy to understand J Pole Antenna Calculator for HF, VHF, and UHF amateur radio bands.  Just enter the operating frequency and calculate the dimensions of your J Pole Antenna.  Using this type of antenna can be a bit tricky, so G.E. recommends the following additional step:

"On most of the J Pole designs out there, a choke should be used as close to the feedpoint of the antenna as possible to help prevent rf on the feedline and creating difficulty with SWR readings. For 2 meters, the coil is 4 turns of coax at 5 inches in diameter. You should get good results with the choke within 3 or 4 inches of the feedpoint on 2 meters.
Hint:
Use the last part of your feedline as the choke before attaching to the feedpoint!"

I've made a few J Pole antennas over the past few years, and they work great on the VHF and UHF bands.  J Pole antennas should give you about 3 dB gain over a monopole antenna.  One of these days, I'll make a J Pole antenna for 20 meters. That should be an interesting project.

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Aloha es 73 de Russ (KH6JRM)