Hi David, and thanks so much for writing us! I’m glad you are finding the educational material helpful.
If this graphic is a bit confusing, I bet you’re not the only one, so thanks for helping us make it better by contacting us about it!
The top graphic (lots of networks, red/blue color scheme) illustrates what would happen if you tried to put a network on each of the 11 channels. Lots of adjacent-channel interference, which is bad. The text above the red/blue graphic explains it a bit:
“Each channel on the 2.4 GHz spectrum is 20 MHz wide. The channel centers are separated by 5 MHz, and the entire spectrum is only 100 MHz wide. This means the 11 channels have to squeeze into the 100 MHz available, and in the end, overlap.”
But I think it could be much more clearly explained, and even better clarified by a caption under both graphics. Do you think that would help? I’ll post again here when it’s fixed, if you wouldn’t mind letting us know if that clears it up for you.