Dipole doesn't need an earth ground. What I have found is that a choke or matching balun is a good idea. If you are keeping it cheap and simple try a choke. #14awg wire will handle the power you are using fine. Also make sure to weather proof your solder connections at the so239. I used hot glue. My first one came out great and at only 15ft placed horz it kicks butt over my vert when dx is rolling in the right way. Fun stuff. Keep at it and enjoy. If ylu plan on building more antennas get an antenna analyzer, they are worth every penny and will save equipment damage! Just had a local blow 2 radios with a bad antenna, swr was only 1.3, but the ohms were at 70-75. Also had a very high X value. At any rate have fun and get that thing up as high as you can. The higher the better.