Mounting an accessory antenna on the roof of your car provides the best reception for cell phones, CBs and ham radios. When mounting a non-magnetic antenna to a vehicle, you will need to drill a hole through the vehicle roof to provide an entry point for the antenna cable. Drilling the hole correctly will ensure you do not damage the area of the roof surrounding the hole. Inspecting the area below the hole will eliminate the possibility of damaging electrical wires running below the hole location.
Cover the location you need to drill the hole in the roof with masking tape. Mark the centre line of the hole on the masking tape with a pencil.
Set the point of a centre punch on the marked-hole location. Tap the back of the centre punch with the head of a hammer.
Secure a 1/8-inch drill bit into the chuck of a variable speed drill motor. Place the tip of the drill bit in the depression made by the centre punch. Drill through the roof using light pressure to avoid denting the roof and to avoid drilling through the interior headliner.
Pull the interior trim away from the headliner. Pull the headliner down from the roof. Inspect the area where the 1/8-inch hole resides in the roof. Move any wires near the hole.
Exchange the 1/8-inch drill bit for a step down bit. Read the installation instructions included with your antenna to determine the correct hole size. Mark the correct size step of the step down drill bit with a paint marker.
Drill through the roof -- using the 1/8-inch hole as a guide -- with the step down drill bit. Stop drilling when the marked step penetrates the roof.
Wear eye protection to avoid getting metal chips in your eyes.