The standard circulating PDF is a "Raster" image—a flat picture of the pages. A "better" version would ideally be a "Vector" PDF or an OCRed (Optical Character Recognition) version. This allows the user to search for terms like "Monostatic-Bistatic Theorem" or "Rayleigh Region" and find every instance, rather than manually flipping through blurred pages.
: Exploiting updated printing technology, the second edition features significantly improved illustrations , making complex wave patterns and measurement setups much easier to visualize.