Herd bumper mounts is what I want to try, but actually getting one on a real truck is turning out to be a challenge.
No longer resonant at 19 mhz. Read thoroughly. Bottom load= wide bandwidth. Center load = narrow bandwidth.
The loading has absolutely nothing to do with bandwidth. That is strictly a function of surface area, if you understand antennas as you claim, you know that at our frequencies, RF travels on the outside of the conductor. Loading determines angle of radiation, basic ARRL handbook stuff. Snake oil, and you know it.
If i had a big ole moose bumper on my trk,its where my ant would be..Something along the lines of the escort cars that have the pole checking height for the over dimensionals