A portable file server includes a radio field intensity input unit, a current controller, and an antenna. The communication apparatus is capable of conducting fax communications via an IP network using a plurality of sessions. A rear light judgment value is calculated as a difference between a central photometric value and a peripheral photometric value of a photometry area, and is compared with a predetermined rear light threshold value, to judge whether the scene is backlit or not. The insulating interlayer group 30 is formed by an insulating material having a lower dielectric constant than that of the insulating interlayer group 20. Separate active regions may be formed such that active regions associated with an access transistor andor a pull up transistor are noncontiguous with, and narrower than, an active region associated with a pull down transistor of the inverter. When the first structure is secured to the second structure, the connection shank presses the protrusions to enable the elastic waterproof ring to deform outwardly and inwardly simultaneously.