It's an antenna for the 146 MHz 2 meter band. It's a vertical dipole. They work pretty well but they are the "wrong" impedance, ~73 ohms in free space, instead of the 50 ohms we normally shoot for.
To make it as cheap as possible, I used coax from Walmart designed for the TV market. It was well under $20 for 50 feet. The problem with that stuff is that it is 75 ohms, not the 50 ohms we usually use. But that goes well with the antenna.
The other problem with the RG-6 coax is the TV style F connectors on the ends. I have an F to PL-259 adapter for the rig end. At the antenna, I cut the end off, stripped the insulation, and, using brass 8-32, bolted the inner conductor and (I got lucky!...) braided shield (in addition to the foil I was sure I would find) to the two ends of the dipole, which are ~19 1/2" brass welding rods. I covered the coax and connections in a huge glob of hot glue.
With the load (antenna) and feedline nearly perfectly matched in impedance, the SWR *on the feedline* is nearly flat, so losses are low. Expecting 50 ohms instead of the 75 it's seeing, the transmitter sees an SWR of around 1.5:1 --perfectly acceptable.
I did all that connecting on a plastic lid from a bird food jar, at the end of a ~3-4' fiberglass rod which also serves to keep the coax perpendicular to the dipole for about half a wavelength (A Good Thing). At the other end of the rod another jar lid holds the coax in a gentle curve on its way down to the mast about 4 feet down, where I have it anchored with cable ties the rest of the way down the mast.
The 20' mast (mounted with its base up about 2' for a total height of ~22') is pine 8' 1x2s bolted side by side (with their joints at alternate 4' intervals) using 8-32 bolts, washers, and locknuts.
The whole assembly is super lightweight, and effortlessly handled. It's a breeze for one person to pick it up and just swing it up into position. (My adult daughter Jordan helped me by anchoring the bottom bracket while I swung it up, just to keep the part I wasn't watching aligned for the final position).
I painted it all flat black to reduce visibility.
The coax and cable ties are black, too, and rated for outdoor use.
A friend of mine is fond of pointing out that a quarter-wave groundplane would be a better performer. That's probably true (they're really very good), but, still... It would be tough to get better bang-for-the-buck out of an omnidirectional hand made antenna.
