Antenna Q calculator

http://owenduffy.net/calc/VswrBw2AntQ.htm

Determine the efficiency of your antenna
and the ability to hear weak stations.
The higher the number the better.

 

Write down the lowest frequency your SWR increases to 2.0 write down the highest frequency your SWR increases to 2.0 and that tells you the bandwidth and whatever that number is when you subtract the smaller number from the large number that's your bandwidth and plug that number into the formula

 

There is a formula..
Q = ƒc ÷ (ƒ2 – ƒ1)
Q equals resonant frequency divided by bandwidth.
Fc equals the freq that x equals 0
F2 equals the highest frequency at 2.0 SWR
F1 equals the lowest frequency at 2.0 SWR
Subtract the smaller number from the larger number to figure out your bandwidth