2m Ladder Line (Window Line) Slim Jim

by admin 2 Comments

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.

Design watermarked by N4UJW and found at the link above from KE4NU.

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.

Good luck!

Index: 12

Comments ( 2 )

  1. Michael
    Good Day. Do you have any designs for 220 MHz? I have plenty of ladder line and would like to practice my soldering skills. Thanks and 73. Michael Lane. KN6BXX.
    • admin
      Hi Michael. Sorry for the delay, I missed all the comments awaiting approval. I have not tried 220 MHz but that's a fun idea. I only have a 5w cheap handheld capable of that band but here in VA we have a great linked 220 system called KG4HOT. I am a bit too far for that system from home but the times I've been in the system footprint, I ran my dual band 2m/440 mobile with a ~2:1+ SWR so maybe designing one for the band would be a good future project here. Would be definitely better than that antenna. Appreciate the idea!

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