JPS6489702A - Directional coupler - Google Patents

Abstract

PURPOSE:To operate to cancel a component to deteriorate a directionality to occur at two coupling parts and to improve the directionality by providing a main line and a coupling line and connecting the section between two coupling parts with a line having a different length by only about half wavelength. CONSTITUTION:Two main lines L1 20' and 10' of two coupling parts 50 are connected to a first line 51 of a length l1 of the 1/4 wavelength of the use frequency and two sub-lines l2 40' and 30' are connected to a second line 52 of a length l2 of the 3/4 wavelength. The phase of an electric power Pri to appear through channels 20 10' 20' 30' at a coupling terminal 30 and an electric power Pr2 to appear through channels 20 30' 40' 30 at a coupling terminal 30 is dislocated only by pi, and becomes the reverse phase relation. Consequently, by such a constitution, the electric power made incident from an output terminal 20 becomes the cancelling condition and does not completely appear at a coupling terminal 30 and the coupler with a good directionality is obtained. The coupling degree from an input terminal 10 to a coupling terminal 20 is constant over a wide frequency band even at the time of a micro-strip construction.