I made this chart a while ago to help me to come to grips with the various bands in the EM spectrum and to visualise wavelengths and frequencies.
The wavelengths were gathered from a couple of different sources ( I think Wikipedia ranked pretty high in the sources
) so there may be some dispute over some values.
It's set up to print as an A3 sheet for a poster for the Obs, but yuo should be able to porint it on A4 and still be legible... just!
If you would like I can zip and post the original Excel workbook.
Al.