Two-port isolator and communication apparatus

A two-port isolator comprising:

• a permanent magnet;
• a ferrite to which a direct-current magnetic field is applied by the permanent magnet;
• a first center electrode disposed on the ferrite, the first center electrode having one end electrically connected to a first input/output port and the other end electrically connected to a second input/output port;
• a second center electrode disposed on the ferrite so as to cross the first center electrode in an electrically insulated manner, the second center electrode having one end electrically connected to the second input/output port and the other end electrically connected to a third port as a ground;
• a first capacitor electrically connected between the first input/output port and the second input/output port;
• a termination resistor electrically connected between the first input/output port and the second input/output port;
• a second capacitor electrically connected between the second input/output port and the third port;
• and
• a circuit board including the first and second capacitors and the termination resistor;
• wherein
• the ferrite has a first principal surface and a second principal surface that are substantially parallel to each other, a long-side length of the first principal surface and the second principal surface being about 1.5 to about 5 times a short-side length, the first and second principal surfaces being substantially vertically disposed on the circuit board;
• the permanent magnet is disposed on the circuit board so as to apply a magnetic field to the first and second principal surfaces of the ferrite substantially vertically to the principal surfaces;
• and
• the second center electrode is wound between one and four turns around the ferrite.