A slot-fed Yagi aerial includes: a cable, a reflector, an active dipole and directors, wherein, the reflector, the active dipole, etc. A power-on self-test is executed, and an initial backup memory is reserved in a memory. The grounding tool includes: a contacting head that can contact the grounding tool and the metal film; an arm portion arranged at the end of the contacting head; a shaft arranged at the other end of the contacting head, and rotating the arm portion. The display unit is disposed on the casing surface.