Communication apparatus and communication system

A communication system comprising:

• a first communication apparatus;
• and
• a second communication apparatus,
• wherein the first communication apparatus includes a first coil, and a first antenna for reception, and
• wherein the second communication apparatus includes
• a second coil coupled to the first coil of the first communication apparatus using at least one of an electric field or a magnetic field,
• a power transmission circuit that performs wireless power transmission to the first communication apparatus at a predetermined power transmission frequency via the second coil, and
• a second antenna for transmission, and
• wherein the first communication apparatus includes,
• a receiving circuit that receives via the first antenna differential signals transmitted from the second communication apparatus via the second antenna, and
• a high-pass filter circuit that prevents a noise which is caused by the wireless power transmission from entering the receiving circuit from the first antenna, and
• wherein the first antenna includes an electrode configured to detect one of the differential signals transmitted from the second communication apparatus and an electrode configured to detect an other of the differential signals transmitted from the second communication apparatus.