Abstract: The invention provides a gas suction pump device equipped with a casing having a substantially rectangular frame-like sectional shape and formed slenderly in a gas flowing direction and into a size holdable by grasping with a hand, a control circuit board provided in the casing so as to extend in a longitudinal direction along the upper wall of the casing, a pump unit arranged in a region on the side of one side wall on the lower side of the control circuit board in a state that one end and the other end of a gas flow path defined by the pump unit have been connected to a gas inlet port and a gas outlet port, respectively, and a battery fitting chamber provided in a region on the side of the other side wall. The invention also provides a gas alarm unit constructed by connecting the above pump device to a portable gas alarm device provided with a specific gas feed adapter through a connecting tube.

Abstract: A plurality of cylindrical inner conductor portions having different diameters are connected with each other to form an inner conductor. The inner conductor portions include high-impedance portions and low-impedance portions. The inner conductor is formed within an outer conductor with a nonuniform inner diameter.