METHOD AND APPARATUS FOR SENSING PROXIMITY OF AN OBJECT USING NEAR-FIELD EFFECTS

摘要

In a method and apparatus for sensing proximity of an object using near-field effects, modulated radio frequency energy is fed to an antenna (28). The antenna radiates this modulated radio frequency energy to charge the surface of an object (30). When the position of the object changes, the impedance of the antenna due to near-field effects changes. This impedance change is detected to provide an indication of the object's movement. The sensing device may be packaged to be inserted into a wall to provide a sensor having a leak-free seal.