Think back... you just got your first license. These daze [sic], it's the TECHNICIAN. In yon olden daze, it was the NOVICE. In either case, you had/have 2m priviledges. You save up your money, and get your first 2m radio, then comes that part of the test that you kind of remember.... ANTENNAS.
Uhhhh, what kind to buy... maybe I can make one..... Uhhhhh, maybe.
Long ago, in the Land of Oz, there was a very smart man (or lady) (everybody's Elmer) who said "Well kid, ya' go inta' yer' Mom's closet and bring me back some-a-them coat hangers!" The number was usually five, and you were admonished to pick them all the same, and the nicest ones ... that's right - throw the coats on the bed - nobody will notice for a while.
You are about to pass your ham radio RITE OF PASSAGE. i.e. Making a "Coat Hanger Ground Plane" for 2 meters.Straighten out the hangers, and cut one (1) in a length of 19 1/4". Cut the other four (4) to a length of 20 1/4". Using some sandpaper (steel wool works, too) clean all the paint off of ONE end of each piece, to a length of about 1/2". Now, put the jack UPSIDE DOWN (threads pointing down) in a small vise (careful! Don't bugger the threads up), and holding the 19 1/4" piece ABSOLUTELY VERTICAL, solder it into the center pin of the SO-239 jack... (ATC... "allow to cool"). Now, we put a bend onto the cleaned end of each of the other pieces (20 1/4" long), and solder them into each of the four holes in the jack (ATC)... space at 90 degree intervals - sticking out horizontally from the jack. Holding the "arms" with a pair of pliers (near the jack, so you don't break the solder joints), bend each radial leg down at a 45 degree angle FROM THE HORIZONTAL, and AWAY from the radiator. Congratulations - you've just built an antenna that will provide coverage from about 143 to around 150 mHz, at an SWR that's absolutely FLAT (1:1), if you play with the adjustment a bit. (best results achieved by making sure the radiating element (center) is now pointing UP... I don't think it works better - but it sure is easier to mount. Besides, you didn't spend $60.00 for a factory-made fancy-schmanzy one that doesn't work any better than THIS ONE.
Now, we use it:
Assuming you have a piece of RG-8/U or RG-58/U coax (52 ohms) with connectors ON it, already (next article deals with the CORRECT way to put on a PL-259!), simply screw one end onto the antenna jack, the other one into your radio, and you're in business. Novel mounting ideas include taking a piece of 3/4" EMT (electrical metallic conduit) for a mast, run the coax through the pipe, and the antenna will sit atop the pipe... looks factory. My old trick when I was in the Navy and in college, was to make one of these with a small hook at the top of the radiator (center element)... now, you can hang it from a piece of thread or string, from a thumb-tack in the ceiling.
These can also be made for 222 mHz and 440 mHz, although one must include some capacitance on the UHF version to offset reactance... see an older ARRL handbook.
Radiator - Length (inches) = 2808 divided by the frequency in megahertz
Radials - Length (inches) = Radiator length x 1.05
April 6, 2008