FIG. 7 is a characteristic diagram showing a result (1) of calculating the pass characteristic B and the reflection characteristic C of the high frequency filter 1 by means of a circuit synthesis calculation. In the circuit synthesis calculation in FIG. 7, the capacitances C1, C2 and C3 in the equivalent circuit shown in FIG. 6 are set to 1.2 (pF), 2.6 (pF) and 1.2 (pF) respectively. The characteristic impedance of each of the coupled lines 202 and 203 is set to 67 (Ω), and the electrical lengths d1 and d2 of the coupled lines 202 and 203 are each set to 30.2 degrees at 6 (GHz) which is the cutoff frequency. The characteristic impedance of each of the connection portions 200 and 201 is set to 50 (Ω). The pass characteristic B is an S21 characteristic, and the reflection characteristic C is an S11 characteristic.
