The Slim Jim Antenna is a relative of the J-pole Antenna. Many claim the Slim Jim Antenna has quite a bit more gain than the J-pole. After researching and looking at antenna models I do not agree. One benefit most agree on is that the Slim Jim has more bandwidth or a larger range of frequency with a usable SWR level.
Construction is similar to the J-Pole built in our last post. I am using 14 awg THHN for the radiator and stub. RG58 is used for the feed line and open air choke. 1 1/4″ pvc is used as a form for the choke. The pvc ic cut 2 1/2″(6.35cm) long.
For the Slim Jim, I wanted to experiment with the matching section. This was an improvement for waterproofing, but refinement is needed. Terminal strips were used to attach the coax to the feed point. This made a good connection. The terminal strips were a little long and got in the way while tuning. The tuning process is exactly the same as the J-pole antenna.
Overall the build worked out well. Like the J-pole this antenna coils ups well and can fit in a backpack. The extra copper does not add much weight to this antenna. More prototypes of the matching section will be made. After testing different matching sections future post will be made.
Slim Jim and J Pole calculator
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