2M Ladder Line Antenna
a.k.a Slim Jim Antenna
The Slim Jim antenna is similar to the J-Pole with increased RF energy at the horizon. I like it because it is easy to build and has a very wide 2:1 SWR bandwidth, about 6% (142-150 MHz). This antenna gives you about twice the gain as a standard J-Pole and two S-Units over a ¼ WL vertical when compared for point to point line of sight work. The antenna is impedance matched to the coaxial feedline by the stub. The coaxial shield is connected to short element and the coax center conductor is connected to long element. Best SWR is achieved by sliding the connection up and down.
Building a 450 Ohm Ladder Line 2M Slim Jim
2M Slim Jim built from a five foot scrap of 450 Ohm Window Ladder Line
The as built dimension are shown here in inches.
Looking at the coaxial feed connection you can see two small cable ties attached with crushing for
strain relief and RTV added after soldering to prevent slipping that might fatigue the connection.
Nylon cord or fishing line support the antenna from the top.
The in band SWR is 1.2 to 1.5 and the 2:1 SWR bandwidth
extends beyond the band from 142 to 150 MHz
Building a PVC Water Pipe 2M Slim Jim
Below is a 2M Slim Jim built from a five foot scrap of 1/2 Inch Schedule 40 PVC Pipe and #14 AWG Bare Copper wire. The pipe provides the structure and spacer. The wire is glued to the pipe to keep the spacing.
The as built dimension are shown here in inches.
The coaxial feed connection is attached with one small cable ties for strain relief
and RTV added after soldering to prevent slipping that might fatigue the connection.
Nylon cord or fishing line support the antenna from the top.
