Awe the debate on CB antennae and coax. There is alot of info in the CB posts.
http://board.marlincrawler.com/index.php?board=33.0I've read that duals are worthless unless your truckers and using a radio that is followed up with a amp (which is illegal). Why? A single antenna is designed for 360* signal. Duals are designed to reach out up or down the road in the direction your traveling. Which is why truckers use them, and they have to be at minimum of 6' apart, or it won't work. And most rigs aren't 6' wide, which is why truckers mount them on the farthest points apart. ie mirrors.
Cable length, and antenna all have to be a certain length. And antenna's need to be mounted in a open, unobstructed area. ie roof. But that isn't possible most of the time. There is a whole science and debate on this subject. But I got to go to work.