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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 Readings Heres the reading I've 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. 73! MOHAMMAD, 9W2WTF ---------------------------------------------------- ANOTHER PLEASED BUILDER REPORTS HIS GOOD LUCK! by Robert Carr  KD8FQM I needed an antenna for the VHF Marine Band. I decided to build a Slim Jim according to your article on Hamuniverse.com. I cut the antenna for a center frequency of 156.8MHz (Marine Channel 16) and find the SWR to be virtually 1.1:1 across the band. The antenna is mounted to a 6ft piece of PVC. I also used the nut and bolt gap adjuster shown elsewhere on your site. And used the sliding SWR adjuster of KE5FXU's design. Works great. See photo below: PVC SUPPORT AND SLIM JIM Notice "SWR ADJUSTER AND VARIABLE GAP FOR SWR FINE TUNING" And now....part of..... "The rest of the story"........... I used 1-1/2" PVC. The distance between the 2 arms is 26", the arms themselves are 6" long. I drilled the 2 holes using a 5/8" dia. forstner bit in a drill press. The length of the mount is the remainder of a 10' piece of PVC after the other 3 pieces were cut. I had planned to solder a 1/2" coupler to each leg to keep the antenna from sliding down in the mount. This proved to be unnecessary due to the amount of friction between the copper tubing and the PVC. The antenna does not move easily in the mount. I put caps on the open ends of the pipe to keep "critters" out. I will probably route the feedline through the PVC, and use the PVC as a form to wind a balun just before it connects to the antenna. Just FYI, while I was tuning the antenna, I heard a boat call the harbormaster for a marina 20 miles away. The antenna was still at ground level and I was adjusting the SWR using my hand held. I've not heard from this marina before. I have great expectations for the antenna when I get it 50' up in the air. The planned use for the antenna is a USCG Auxiliary Fixed Land Radio Facility. We live about 25 miles north of Coast Guard Station Alpena. When their boat comes north, the station cannot maintain radio contact with the boat. I hope to fill that gap. I like the antenna so much (and it isn't even mounted yet) that I am going to build one for 2 meters and put up on the same 30' mast. The "rest of the story" is that 30' mast goes on top of my 20' garage. I am very pleased with the results of the antenna. Thanks for a great resource, 73, Robert Carr KD8FQM Also see the original Slim Jim Project here for reference!      Hamuniverse.com uses Green Geeks Web Hosting!