<p>A microstrip line is composed of a grounding conductor (11) and a strip conductor (12) which sandwich a dielectric substrate (10). The microstrip line is provided with a conductor section (14), which has at least one groove (21) which is formed to orthogonally and three-dimensionally intersect with the strip conductor (12). Thus, the microstrip line has substantially more uniform passing frequency characteristics compared with those of microstrip lines relating to conventional technologies.</p>
