| 摘要 |
An alarm system for surveillance of a container located within an electric or electromagnetic field surrounding the container includes a detector device which comprises generating elements for generating an electric or electromagnetic field, balancing elements for building up a balanced electric or electromagnetic field, filtering elements to prevent the detector device from being affected by chances in temperature and humidity. The container includes conductive material and connected to the detector device so as to constitute an antenna for sensing small capacitive changes in the electric or electromagnetic field. The generating and balancing elements respectively generate and build up an electric or electromagnetic field around the container. |
