uniden cb

Mike.
No need for the earth, it is taken care of by the outer shield of the coax cable which will be earthed at the transeiver.
mike39

it would not hurt to earth it at the antenna. it will ultimately ground at cb through the outer sheath however a nice short earth to the chassis would improve the reception quality. also relying on the outer sheath of the cable to provide your ground (earth) would leave you open to picking up "noise" (electrical interference) from such things as devices connected to the cig socket, air con, cd player, clock, instrument panel etc or whaterver the coax cable passes near, may not be much or enough to worry about, but like i said a direct earth would improve it. a ring terminal placed under antenna nut with a short wire going to the nearest mounting bolt of the smart bar would be sufficient. try with and without and see if you can notice the difference.