Big Wheel Antenna Mount
When such a pole is attached to the rear bumper or to a trailer hitch, some of the Big Wheel (about 20″) overhangs the rear of the vehicle. You may feel like you need a red flag dangling to stay legal with this kind of extension.
I solved this problem with a magnetic mount. One magnet of the type used to hold on a CB or 2m whip is not strong enough to handle the inertia and wind load of the Big Wheel. When I found several of these round magnets at a “sidewalk sale” I picked up three. The framework of 3/4″ angle aluminum from the local hardware store is held together with small nuts and bolts from the same source. See Figure 1.
The logic I attempted to use was to put a long base on the frame to counter the greatest force against the antenna: the relative wind from the direction of the vehicle’s movement. Of secondary importance is the lateral stability since this will be less than the head-on force of the relative wind, even when passing oncoming trucks and busses. The main height limitation is what you feel comfortable with, considering your area’s trees and your garage door clearance. However, the plane of the antenna should be at least 21″ above the roof of your vehicle.
This mount has proven highly satisfactory in the year since it was placed into service. One of its real advantages is its portability from vehicle to vehicle. Figure 2 shows the front view and Figure 3 is the side view of the mount.
Originally posted on the AntennaX Online Magazine by Franklin W. Nogues, W5GVE
Last Updated : 6th March 2024