A signal input/output line 101 is used for input and output of a signal. A
first resonating part 102 is connected to the signal input/output line
101 at one end and is opened at the other end. A second resonating part
103 is connected to a ground conductor 105 at one end and is opened at
the other end. A connecting line 104 has a predetermined length and is
connected to a point of connection between the signal input/output line
101 and the first resonating part 102 at one end and is connected to a
predetermined point on the second resonating part 103 at the other end.