Antenna for tire pressure information sending apparatus and tire pressure information sending apparatus using the same

A tire pressure information sending apparatus comprising:

• a circuit board;
• a pressure sensor placed on the circuit board, for detecting air pressure of a tire;
• a sending circuit placed on the circuit board, for sending information on the air pressure detected by the pressure sensor by radio waves;
• and
• a radiation electrode placed on the circuit board, for sending the radio waves, the radiation electrode having a loop surface substantially perpendicular to a principal surface of the circuit board,
• wherein the pressure sensor and the sending circuit are arranged within the loop surface.

An antenna for a tire pressure information sending apparatus comprising:

• a circuit board provided with feeding electrodes;
• a pressure sensor placed on the circuit board, for detecting air pressure of a tire;
• a sending circuit placed on the circuit board, for sending information on the air pressure detected by the pressure sensor by radio waves;
• and
• a radiation electrode having a loop surface substantially perpendicular to a principal surface of the circuit board, the radiation electrode sending air pressure information of a tire onto the principal surface by radio waves,
• wherein a magnetic field vector is parallel to the circuit board, and
• wherein the pressure sensor and the sending circuit are arranged within the loop surface.

A tire pressure information sending apparatus comprising:

• a circuit board;
• a pressure sensor placed on the circuit board, for detecting air pressure of a tire;
• a sending circuit placed on the circuit board, for sending information on the air pressure detected by the pressure sensor by radio waves;
• and
• a radiation electrode placed on the circuit board, for sending the radio waves, the radiation electrode having a loop surface substantially perpendicular to a principal surface of the circuit board,
• wherein a magnetic field vector is parallel to the circuit board, and
• wherein the pressure sensor and the sending circuit are arranged within the loop surface.