An external index detection unit receives an image sensed by a camera, and detects an external index set in a real scene. A selective directional transceiver is used to determine the relative direction of the target object, even in a multiple-story building, from a hand held component of the object locator. Notches are formed at the edges of the dielectric substrate in the vicinities of coupled-line pattern segments formed on a dielectric substrate. The notch filter filters the envelope signal to generate a first filtered signal, and a zero point of the notch filter corresponds to the carrier frequency of the AM signal.