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.