Three mutually intersecting central conductors are positioned on ferrite to
which a direct current magnetic field is applied, the port portions of two
of the central conductors are branched and one branched portion of each is
extended and bent so as to form an inductor. These inductors and
capacitors with one end connected to a ground terminal make up series
resonant circuits. The resonance frequencies of the series resonant
circuits are set to approximately two times and approximately three times
that of the center frequency of the pass band of the device which is the
fundamental frequency, thereby causing attenuation of the second harmonic
frequency and third harmonic frequency of the fundamental frequency, thus
acting as matching capacitance of the fundamental frequency. Accordingly,
a small nonreciprocal circuit device having a great amount of attenuation
of a particular frequency is obtained without increasing costs, a
nonreciprocal circuit device, and a communication device using the same,
are provided.
