Patent ID: 8203401

Claim:
A strip line filter comprising: a dielectric substrate having a top surface and a bottom surface; an insulating layer which has a relative permittivity smaller than that of the dielectric substrate on the top surface of the dielectric substrate a ground electrode arranged on the bottom surface of the dielectric substrate; a plurality of resonant lines arranged on the top surface of the dielectric substrate so as to face the ground electrode through the dielectric substrate; and input/output electrodes connected to a corresponding resonant line of the plurality of resonant lines, wherein a first resonant line among the plurality of resonant lines includes a main line section arranged adjacent to a second resonant line on a first side of the second resonant line and a branch section which is branched from the main line section and which is arranged adjacent to the second resonant line on a second side of the second resonant line, and wherein the branch section is arranged on the top surface of the dielectric substrate and includes a sub-line section which is arranged adjacent to the second resonant line on the second side thereof and a connection section which is arranged on the insulating layer and is separate from the dielectric substrate and connected to the main line section and the sub-line section.