PURPOSE: To obtain a transmission characteristic with a broad band by connecting a flat capacitor in a standing way along a longitudinal running part caused by cutting off a strip conductor so as to eliminate the equivalent spread of the width of the strip conductor.

CONSTITUTION: A longitudinal running part 13b formed by cutting off the strip conductor 12 as a slot along nearly the lengthwise direction of the strip conductor 12 is formed to the cut-off part 13 cutting off the strip conductor 12. The flat capacitor 15 thinner than the width of the strip conductor 12 is stored along the longitudinal running part 13b and an electrode face 16 is connected electrically to the strip conductor 12 clipping the longitudinal running part 13b. Thus, the width of the strip conductor 12 due to the connection of the capacitor 15 is not spread. Thus, the DC component is blocked and a broad band transmission is attained.