The parameter values which are the capacitance values, the characteristic impedances and the electrical lengths shown in FIG. 6 are first determined, on the basis of the circuit configuration of a low pass filter which employs a J inverter in which each of the electrical lengths d1 and d2 is 90 degrees. FIG. 8 is a characteristic diagram showing a result (2) of calculating the pass characteristic D and the reflection characteristic E of the high frequency filter 1 by means of a circuit synthesis calculation. In the circuit synthesis calculation in FIG. 8, the capacitances C1, C2 and C3 are set to 0.727 (pF), 1.455 (pF) and 0.727 (pF) respectively. The characteristic impedance of each of the coupled lines 202 and 203 is set to 32 (Ω), and the electrical lengths d1 and d2 of the coupled lines 202 and 203 are each set to 90 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 D is an S21 characteristic, and the reflection characteristic E is an S11 characteristic.

As shown by the pass characteristic D of FIG. 8, by setting each of the electrical lengths d1 and d2 to 90 degrees, a stopband is formed in the vicinity of 10 (GHz) which is the second harmonic with respect to 5 (GHz) which is the passing frequency. More specifically, the high frequency filter 1 can form a stopband in the frequency band of unnecessary harmonic components.