DIRECTIONAL COUPLER

摘要

PURPOSE: To provide a small-sized directional coupler with less insertion loss where a main line and a sub line have a sufficient self inductance. CONSTITUTION: Conductor patterns 2a, 3a for the main line and the sub line are formed on an upper side of an insulating board 1 by a method employing the photolithography technology. The main line conductor pattern 2a and the sub line conductor pattern 3a are formed in spiral while being located in parallel. In order to decrease the main line self inductance more than the sub line self inductance, the line width of the sub line conductor pattern 3a is selected narrower than the line width of the main line conductor pattern 2a. More concretely the line width of the sub line conductor pattern 3a is selected to be 50% or over and 90% or below of the line width of the main line conductor pattern 2a.