Well i hate to break you'r train of thought but the whip and coil was recommended by a 2-way radio shop tech . As i've said before my 49" whip and the NMO 150 coil do just fine for my set up . Now a 1/4 wave NMO is preset at the factory to operate at 136-512 mhz . My father ran this same ant on his 4-runner for 3 yr's ...Motorola MaxTrac 16 ch w/ the 18" mounted on the driver side front fender ...I know the radio had to be computer programmed for the correct input and output freq's ...