e/Beam diameter

Information
has gloss	eng: The beam diameter or beam width of an electromagnetic beam is the diameter along any specified line that is perpendicular to the beam axis and intersects it. Since beams typically do not have sharp edges, the diameter can be obtained in many different ways. Five definitions of the beam width are in common use: D4σ, 10/90 or 20/80 knife-edge, 1/e2, FWHM, and D86.
lexicalization	eng: beam diameter
instance of	c/Antennas (radio)