Topband: 160 Meters Mobile Antenna Suggestions

[Tom Rauch]

> Don't forget, if the Q isn't high enough (and for sure it wont be on 160
> meters), the bandwidth will be wider due to all the coil losses! This is
> one of those things you have to think about twice!


Hi Joe,

Contrary to popular rumor or opinion, bandwidth is not a good indicator of
antenna efficiency. This is the case even in something that appears simple,
such as a mobile antenna.

Bandwidth is closely tied to the value of reactance required to correct
reactance of the antenna. An inefficient inductor with a great deal of
shunting capacitance across turns and a small stinger above the coil will
provide much narrower bandwidth than a loading coil with low coil
capacitance and a larger stinger or more capacitance above the coil.

My highest efficiency mobile antennas also happen to have the greatest
bandwidth. That includes a large optimized #10 air wound coil (Q~400) with a
six foot hat. The narrowest antenna I have is a modest Q (~200)
low-efficiency Master Mobile coil wound with #20 wire that requires a short
5' whip above the coil.

73 Tom