Patent ID: 8358184

Claim:
A stripline filter comprising: a dielectric board having first and second opposed surfaces; an insulating layer having a relative dielectric constant lower than that of the dielectric board and is adjacent the first surface of the dielectric board; a ground electrode on the second surface of the dielectric board; resonant lines that face the ground electrode with the dielectric board therebetween; and an input/output electrode for inputting/outputting a signal to/from the resonant lines by external coupling, wherein at least one of the resonant lines includes: an open end side line portion having an open end and no short circuited end, and positioned on the first surface of the dielectric board; and a short-circuited end side line portion having a short-circuited end and no open end, and which extends on the insulating layer and is connected to the open end side line portion, and wherein each of the open end side line portion and the short-circuited end side line portion has a respective line that is in a whirl shape when the dielectric board is viewed from the first surface.