radio is on is vague...
example, in RideRunner and Centrafuse, the radio is ALWAYS ON
its a question of is it ACTIVE, then you would want to raise/lower your antenna
(if you actually have an electric telescoping antenna, cars dont have them anymore)
so if its a non telescoping power antenna, ie AMPLIFIED, just power it when pc is on, or when key is in accessory... no need to overcomplicate