Patent ID: 8730123

Claim:
An antenna apparatus comprising: a first earth plate; and a radio frequency circuit board in which (i) at least one radio frequency communication circuit that communicates a communication signal on radio waves and (ii) a second earth plate are formed, the radio frequency communication circuit including at least one of (i) a radio frequency transmission circuit that transmits a transmission signal as the communication signal and (ii) a radio frequency reception circuit that receives a reception signal as the communication signal, the second earth plate serving as a grounding electric potential of the radio frequency communication circuit, the radio frequency circuit board being arranged such that a plate plane of the second earth plate intersects with a plate plane of the first earth plate, wherein: the first earth plate and the second earth plate are in electrical insulation state at least with respect to signals of frequencies of the communication signal; and a feed of the communication signal by the radio frequency communication circuit is executed by an unbalanced feed for each of the radio frequency communication circuit, while for the each of the radio frequency communication circuit, a feed line in the unbalanced feed is connected with the first earth plate and a ground line in the unbalanced feed is connected with the second earth plate.