Hi I have installed a pni s9 antenna on the roof of my van I cannot get the swr below 1.7. It has a good bodywork earth ,coax is not crushed no shorts. I have a pmr antenna 1ft from it and roof racks, I removed both no difference to swr reading. Do you think that is the limitations of the antenna ? The rig is Lincoln ii+ checked the swr on mfj290.