Wednesday, May 4, 2016

J-Pole Antennas

In my last article about inefficient HT antennas I mentioned that a good gain for an HT should be 2 dB or higher. If this makes your eyebrows raise in question please read that article before ruling me out of presidential race. In this article I want to talk about an antenna that I frequently connect to my radio gear. It is called the J-Pole or J antenna. This is a very strange looking antenna but has some interesting performance characteristics. The following is one of the products that can be found at jpole-antenna.com.


I added the picture to be able to see what one looks like in it's most basic form. You can purchase these fairly cheaply (~$25) or even build one for yourself at rock bottom scrap prices. Actually it is more fun to build and you can learn a great deal in the process. I have used these for years and experienced some amazing results. (continued below...)





If you are using one of these for an HT you will have to mount or hang it at a stationary location and then run your coax cable to your HT and adapt to the antenna connector on the HT. There are many different types of J-Pole antenna designs as well as materials used to construct one. Some have had great success with ladder line. 

A few special notes about the J-pole antenna, depending on the construction materials, is they usually have a large bandwidth, a great radiation pattern for a vertical, and a gain ~2.5dB. It beats a quarter wave vertical antenna by a decent margin. In mounting the antenna you want to make sure it has no electrical connection to the object (mast, house, etc) it is mounted to.  It is best fed by a balun if coax is used otherwise a balanced feed line is acceptable. 

This is just a basic overview of the J-Pole. I will be adding construction tips soon. In the meantime, what have been your experiences with the J-Pole? 

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