We’ve installed a President Bill CB into the 2018 JL and to go with it we are now installing a 4′ Firestik antenna with a Firewire cable. The long 4 door JL can still use an 18′ cable to get from the dash area to the tailgate.
Mounting
The Mopar tailgate reinforcement bracket includes a CB antenna mount so we are using it. The cable will be routed through the tailgate and along the inner passenger side of the Jeep, under the passenger seat and finally to the CB. The Firering cable we are using features a mini UHF connector that allows easier routing through small holes. We started in the rear.
remove the inner cover 
watch the fasteners 
remove the plug 
remove the large UHF connector 
feeding the wire
After getting the wire through the tailgate it was worked behind the plastic lining within the Jeep along the passenger side.
attach to the tailgate arm 
working in the cable 
behind the molding 
cleaned up
The cable exits the molding under the rear passenger side door and goes under the front seat to the CB.
trim the plug for the wire 
wire routing 
antenna installed
Follow the Firestik installation procedure for the antenna end of the Firering cable. There are several mounting options, pick the on that works for you. We included a spring to allow the antenna to move when hitting tree branches on the trail.
Next – Tuning the CB