Planar inverted F antenna with improved feeding line connection

A planar inverted F antenna has a ground conductive plate and a main conductive plate that are short-circuited by a short circuit member. The main conductive plate connects to a feeding line for feeding power to the antenna and includes opposite side ends, a base extending from one side end to a prescribed position in the direction toward the other side end, and a slit extending from the other side end of the main conductive plate up to the prescribed position to form a microstrip line that is connected to the feeding line and at least one excitation conductive plate spaced apart from the microstrip line. The prescribed position includes a feeding point to which power is supplied from the feeding line via the microstrip line having a width such that an input impedance of the antenna at the feeding point and a characteristic impedance become Z.