Question about impedance matching

Hi,

I am reading quarter-wavelength transmission line transformer on an article: The Yin-Yang of Matching: Part 2?Practical Matching
Techniques.

I do not understand the second sentence about 22%. This percentage is regarding to which bandwidth? It gives as an example of the first sentence, i.e. for ratio 6:1, it is narrower? I do not see that from the passage. Could you explain it to me?

Thanks.


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The bandwidth of a quarter-wavelength transmission
line transformer decreases with loads higher or lower
than the desired resistance. The bandwidth is about 22%
for a ratio of 6:1 as with a 300 ohm load in a 50 ohm system.
The bandwidth can be improved by cascading multiple
quarter wavelength transmission line sections. Given
in this section is a simple but effective algorithm for computing
the required characteristic impedance for each
section.

It is about the frequency bandwidth which represents 22% of the central frequency.
For example if the frequency is 100 MHz, 22% means the frequency range between 89 MHz and 111 MHz.