2 Meter Slim Jim Antenna
Aluminum Tubing Version
 by 9W2WTF, Mohammad
(See updated information by KD8FQM at bottom of article)

This antenna is specifically built to resonate within the 2 meter amateur radio band
(144-148MHz). This antenna has been build with the help of my friend, Amet who is a trained electrician. It shows a method of using PVC for the vertical element supports and uses curved aluminum tubing.

Slim Jim Plan that we use
Please refer to 2 Meter Amateur Radio Slim Jim Plan post for more information about lengths, spacing, etc, including a 300 ohm twinlead (ribbon) version and see the drawing below:

Among the items used to construct the antenna are :

Aluminium tubeing, 8mm diameter, sold in 10 feet (can be obtained from hardware store, 10 feet, RM10)

U PVC Pipe (15mm-20mm) for holding with T junction, RM4

SO-239 connector (for mobile rig), RM10

Coax Cable (either RG-8 RM7/m or RG-58 RM2/m, quality varies

Tools that we used are (included with cost if you want to buy them):

Bosch hand drill for drilling pipes and aluminium tube ( RM100)

Rivet / Riveter for attaching coax cable to antenna (RM 20)

Bender (RM 30)

wire cutters

Hack saw for cutting pipes and aluminum (RM 3)

and oh yes, we *dont use* any torch welder for this one

As you already might guess, the cost for constructing the antenna alone cost slightly less than RM30 (~USD 10, except cable and tool cost), the Slim Jim is mounted on the roof of my house with ordinary TV antenna bracket, with the height of close to 40 feet from the ground.

Why build your own antenna? It is a way for me to better understand about radio wave resonance and to learn more about how to build a radio antenna to tune in to specific frequency, something that commercial antenna lacks, because it is built to tune to a wider range of frequency due to market demand.

This antenna is said to have a gain of 3.2dBi, though I dont have confirmation about this information.

SWR Reading

Heres the reading Ive obtained from Diamond SX-200 SWR meter, using 20 watt output power :

• 144 Mhz - 1.2
• 146 Mhz - 1.3
• 148 Mhz - 1.5

The reading is kinda bit off from the center of frequency 146Mhz, I know. this is due to my poor handling with aluminium bender. I've made it almost an inch longer, so that kinda explains the SWR reading is kinda centered on the lower frequency.

However this is way cheaper than buying a commercial antenna which cost me a lot of bucks, and I surely have more fun!

What can be improved?

 If you want the antenna to resonate better, you could replace aluminum tubing with copper or brass tube and replace RG-58 coax cable with a low loss cable such as RG-213 or RG-8 which was used in this experiment.