The origin of the slowly varying component

Abstract
Two main mechanisms have been proposed to explain the origin of the slowly varying component [1] of the decimeter-wavelength radiation from the sun. Both theories [2, 3, 4] are based on the facts that (a) this component of the sun's radiation is relatively steady in output for periods of days; (b) it originates from active regions on the sun; and (c) its magnitude is closely related to the sunspot area in the region.