Development of underground structure cover with slit for radio wave transmission

The development of the underground structure cover is a method of constructing a sewer water level detection system for flood prevention. The challenge in this design is that the metal cover needs to shield as little as possible of the signal emitted from the antenna in the underground structure. In this paper, we improved the penetration of the underground structure cover by opening self-complementary slit in the cover. A water level sensor is installed in the underground structure and connected to an antenna underneath the cover. The underground structure has been modeled, simulated and measured to obtain the antenna characteristic parameters. Through the slit in the cover, the antenna successfully transmits water level data to the outside. The underground structure cover is shown to perform as expected as verified by outdoor measurements.