A good antenna that can be used for the car as well as the house is an HALO. This antenna maintains good omni-directional horizontal polarization. Basically the antenna is a half wave dipole bent into a circle,BUT shorter than a dipole for this frequency. The circumference is 60-70 inches. By useing the gamma match (see above) you can use regular coax.This is a high-Q antenna.So bandwidth is about 200khz. (Perfect for 50.100-50.200 where most of the 6m ssb activity is)
The 2 large discs can be about 4-5 inches round and the small disc about 1.5 inches. Mount the 2 larger discs at the ends of the halo by screwing end caps to the center of them and then the end caps will go over the ends of the halo. Next drill a small hole in one of the larger discs and the same size hole in the exact center of the small disc. Put a 2 inch bolt threw the center and run a nut up the bolt to lock it in place. Then a nut on each side of the large disc to secure the bolt to the larger disc. Mount the gamma rod the same as you did on the beam (see above) BUT bend the gamma to match the curve in the halo. Finally take three 2-3 inch nylon spacers and mount them between the large discs. You should drill 3 holes in a trianle patern and use 3 nylon bolts and nuts. This will ensure that the ends plates do not move around on you. You can mount this antenna on a mast by making some type of bracket for support.
(Just try to put the bracket by the mount where the coax/gamma is so that the mount should not affect the antenna preformance.)
To match the antenna simply move the gamma around a few times(move it in small increments it really tough). Once you get the S.W.R. down below 3:1 then move the small disc by loosening the nut and turning the small disc.(AGAIN move it in small increments)