Abstract: A behind-the-wall antenna system according to the present invention comprises: a wall; a converging reflector (corner reflector) which reflects radio waves so as to form a region behind the wall in which the electric field strength is great; an antenna arranged in the region between the wall and the converging reflector in which the electric field strength is greater than that in the surroundings; and a transmission path connected to the antenna. A resonance space is formed between the front face of the wall and the converging reflector. Furthermore, the distance between the wall and the reflector is adjusted so as to create an impedance matching state between the antenna and the space on the front side of the wall. With such an arrangement, the radio waves are directly used behind the wall.

Abstract: An underground space structure of a buried radio device includes an underground space, a metallic cover on the underground space, and an emission surface having a ring area including a structure material with transmission of electrical waves surrounding the cover. An underground radio device includes an underground antenna arranged apart from the cover in the underground and a radio device connected to the antenna. A radio device on the ground includes an antenna on the ground and a radio device connected to the antenna. The underground antenna and the antenna on the ground are connected via the emission surface including the ring area.

Abstract: A method of detecting the location of a failure (e.g., a sudden leak) in a fluid pipeline network, which can be suitably used for estimation of the location of a failure in a water pipeline network, includes the steps of periodically measuring a flow rate or fluid pressure with sensors arranged at a plurality of measuring points along a pipeline in a water pipeline network; comparing a latest measured amount and a previous measured amount at each measuring point to determine if an amount of change at an arbitrary point has exceeded a predetermined value; and calculating a position at which an amount of change becomes maximum, the position being calculated from the magnitudes of the amounts of changes in respective measured values at the time of the detection. The pipeline network may be a water supply and distribution pipeline network which includes a trunk pipeline and branch pipelines.