This is a quick post about making a “slim jim” 2 meter antenna out of DX Engineering‘s 450 ohm ladder line. I based my build off of KE4NU’s write-up found here: https://www.hamuniverse.com/ke4nu450slimjim.html. I will note my specific findings and measurements below.
I did make this for a trip I was going on right away so I did not take pictures during the build as I normally would have.
Here’s what you will need:
- 450 Ohm ladder line (actually window line)
- Solder / Iron
- Wire cutters / stripper
- Coax and/or connector
- Tape measure
- Antenna Analyzer (if available)
My design was exactly 58 inches, with the two ends soldiered together making a full loop.
Now let’s look at the notch. I cut one inch exactly from 19-20 inches from the bottom of the antenna where the two conductors were soldered together (not the feed point).
For the feed point, as you would expect, it should need some adjustment on the exact spot to solder. The center connector goes to the long side of the slim jim. I had a cut piece of coax already available, so I just used that. My feed point worked best at 55-3/4 inches from the top, or rather, 2-1/4 inches from the bottom junction of the conductors.
Using my AA-650 Zoom Antenna Analyzer, you can see we have a pretty darn good setup:
After everything was tested with the antenna analyzer and soldered in place, it was wrapped with electrical tape. If this were to be outside in the weather, I’d recommend sealing it. Also, I added a bunch of turns with the coax through a mix 31 torroid from Mouser.
I used this in my hotel room hanging from the curtain rod and it still maintained a good SWR. Just remember these antennas are sensitive to nearby objects.