Let’s talk about the slim-jim antenna! Many new hams that get their tech licenses want good performance in the home as well as in the car, but whether they live in an apartment, with family, or under an oppressive HOA, they can’t get away with a good base station antenna.
While the traditional wisdom is to get a mag-mount antenna and slap it on a pie plate or filing cabinet, there is a better, and often more affordable, option out there. Slim-jim antennas are basically J-Pole antennas. J-Pole antennas don’t require a ground plane (so no radials or pie pan needed), and offer significantly more gain than your standard vertical antenna. The design for a j-pole is typically something like this (source: Ham Universe):
While these antennas perform great, they still require a good mounting point just like a vertical antenna, and are in no way portable. That’s where the clever design of a slim-jim antenna comes in! Slim-jims take the same physics of a j-pole and connect the top:
Why is this so great? Well, the simple design lets us take ladder line, which is a strip of two wires isolated from each other with an insulator, and copy this design. The result is a floppy, portable, and easy-to-set-up antenna with great performance!
The real strength of this antenna is its flexibility. By attaching some paracord to the top of the antenna, you can easily hoist it up in a tree for great performance and range and attach the antenna to a handheld! It’s also a great match for an APRS station with its good performance and how easily it can be mounted anywhere!
If you’re stuck in a dorm or have other restrictions at home, this can be hung in the attic, out a window, or even right against a wall and it’ll work! It’s worth noting that having the antenna against a wall, tree, or other structure will reduce performance and maybe even change the SWR a bit, so be aware of how well-matched it is to your radio with an SWR meter or Nano VNA.
Making a 2m slim-jim antenna is pretty straightforward, especially if you already have some ladder-line! They can be made for as little as $15 these days. However, I’d recommend supporting the N9TAX shop. N9TAX produces very good quality slim-jim antennas for a very competitive price. $30 for an antenna including some good-length coax to connect to your radio!
You can visit the N9TAX Labs shop at https://n9taxlabs.com/shop!
If you want to make the antenna yourself, check out this guide:
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