File talk:Sidelobes en.svg

This is a lovely diagram, and I want to use it, but don't understand exactly what it is showing. The info says "This diagram shows the line where the energy is less than 3db compared to an iso emitter" but there are three circles. My guess is that the outer circle represents 0dB, and the one inside that -3dB. But what are the inner two ? Can somebody help ?

92.236.125.191 (talk) 16:29, 18 July 2012 (UTC)Andy Lawrence