In telecommunication, the term radiation pattern has the following meanings:
1. The variation of the field intensity of an antenna as an angular function with respect to the axis.
Note: A radiation pattern is usually represented graphically for the far-field conditions in either horizontal or vertical plane.
2. In fiber optics, the relative power distribution at the output of a fiber or active device as a function of position or angle.
Note 1: The near-field radiation pattern describes the radiant emittance (W·m-2) as a function of position in the plane of the exit face of an optical fiber.
Note 2: The far-field radiation pattern describes the irradiance as a function of angle in the far-field region of the exit face of an optical fiber.
Note 3: The radiation pattern may be a function of the length of the fiber, the manner in which it is excited, and the wavelength. Synonym directivity pattern.
Source: from Federal Standard 1037C and from MIL-STD-188