Slim Jim Antenna

(2m/70cm Slim Jim Antenna - Measurements may vary)

 Over the years, I have made lots and lots of my own antennas. I keep coming back to the 'Slim Jim' and 'J-Pole' antennas because in my experience, I don't think there is a better omni-directional choice. They are fairly easy to build and many calculators can be found on line. The measurements in the above diagram were taken from an on-line calculator, but when I built mine I found that I needed a slightly bigger air gap and my connection point was considerably higher up from the bottom. So some experimentation is needed.

Before my licence, and stretching way back to the 1980's when AM was the only choice, I have worked stations all around the world using, in particular, a J-Pole. The problem is at this wavelength (11m), and more so on the lower HF frequencies, the antenna can get quite large. However on 2m/70cm its a completely different story. I try to keep my antennas in the loft now where possible because they can be an eyesore for the neighbours, especially the 11m ones. I am currently running my UV-5R through a loft mounted Slim Jim. I can easily get into the GB3ST repeater in Stoke on Trent which is about 41 miles from my location. The SWR at the moment is 1.3:1 on 2m but about 1.7:1 on 70cm, so its still a work in progress. 
I am currently working on a 3 element Yagi with a simple RC servo rotator. I have only tested this at ground level, whereas the Slim Jim has about a 20 foot advantage, the Yagi is only just comparable with this. Also, the Yagi is directional, so a lot of twiddling to get the best signal with the rotator. It will probably be a different story when I get it in the loft with some height advantage, because as we know on VHF and UHF, height is king.