LOW PASS FILTER UNIT HAVING COUPLING LINE STRUCTURE HAIRPIN AND RING-HYBRID TYPE DIRECTIONAL COUPLER USING THE SAME

摘要

A low pass filter unit having a coupling line with a hairpin structure and a ring-hybrid type directional coupler using the same are provided to reduce a size by minimizing an area of a ring portion of the ring-hybrid type directional coupler. A low pass filter unit includes first and second transmission lines(11,12) and a plurality of coupling lines(21-24). The first and second transmission lines are connected to an adjacent low pass filter unit. The coupling lines are positioned between the transmission lines. One ends of first and second coupling lines and third and fourth coupling lines are connected respectively. Other ends of the second and third coupling lines are connected to each other. The first and second coupling lines and the third and fourth coupling lines face each other in parallel in a hairpin structure. One end of the first transmission line is connected between the first and second coupling lines. One end of the second transmission line is connected between the third and fourth coupling lines.