An antenna system including a signal source, at least one antenna coupled to the signal source, a matching circuit connected to the signal source at a first port and to the at least one antenna at a second port and operative to match the at least one antenna to the signal source, the matching circuit having a characteristic impedance with respect to the first port and the second port, real and imaginary parts of the characteristic impedance not being defined by the Hilbert transform.

A branching filter includes a first diplexer, a second diplexer, and a third diplexer. An input end of the first diplexer is connected to an input port. An input end of the second diplexer and an input end of the third diplexer are connected to two output ends of the first diplexer, respectively. Two output ends of the second diplexer are connected to first and second output ports, respectively. Two output ends of the third diplexer are connected to third and fourth output ports, respectively.

First to fourth filters of an electronic component are provided in a manner that a first path from the first filter to the second filter includes a second path from the third filter to the fourth filter and is also longer than the second path in a circuit configuration. First to fourth inductors of the first to fourth filters are arranged in a manner that an opening of the first inductor and an opening of the third inductor face each other, an opening of the second inductor and an opening of the fourth inductor face each other, and a pair of the second inductor and the fourth inductor is adjacent to a pair of the first inductor and the third inductor.

In a noise filter circuit, a coupling loop part having a capacitor which is connected to both a positive electrode side input loop line and a negative electrode side output loop line is mounted on a dielectric substrate in a state where a positive electrode side input line and a positive electrode side input end part are connected, a positive electrode side output line and a positive electrode side output end part are connected, a negative electrode side input line and a negative electrode side input end part are connected, and a negative electrode side output line and a negative electrode side output end part are connected.