It covers more frequencies as in wavelengths as in the bigger the wavelength the bigger the length of the antenna (to put it simply). In this case they’re saying you wouldn’t need to make it as large as a conventional antenna to receive the same frequencies, or you could make it large and receive more frequencies.
You can find torrents here if you’re willing to seed 181TB for the full dataset, or 43TB for just zlibrary https://annas-archive.org/torrents