Extended Slim Jim Antenna Project For 2 Meters
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In recent days I have been dreaming about 2 meter antennas in my sleep, and sometimes when I'm awake. several weeks back I built the Slim Jim for 2 meters pictured here on this site.
Today I constructed, what I am calling the Extended Slim Jim. Maybe once it is tested and modeled we can call it the Super Slim Jim. In the mean time Extended sounds like its not overly boastful.
I chose to use 3/4" copper pipe ( I suppose you could use 450 ohm ladder line as well), I followed the diagram that you will find for my Extended Slim Jim Beta drawing.
All the information is there, just so it is clear, as it was hand written and then scanned, the long sections is a full 8' piece of Copper pipe NO CUTTING. it is 2 full wave lengths long on 2 meters.
You can do the 1/4 wave matching section just like a standard J-Pole and it will load quite nicely. Due to weather and such, I only took time to get it down to a 1.3:1 match across the whole 2 meter band. its not perfect, but hey no real complaints either. I will work with this and do more testing. Mr. Steve Finch AI0W was kind and modeled this for me in EZNEC the link is to the right.
This antenna appears to have a slight gain over the regular Slim Jim version. It also seems to have a slightly higher take off angle about 21 degrees and another about 55-60 degrees.
This maybe a great antenna for someone who is relegated to a LOW mounted antenna that can be hidden in a PVC tube, with no radial and no ground required. In such a case this might also make a very strong antenna for working local repeaters, as the gain is very good 6.36db . PSST.... Can someone say flagpole?
The one thing I have found out is that adding more space between the elements may assist the SWR and certainly the bandwidth of the antenna.
feedback always welcome
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