A key equipped with an electronic chip and an antenna embedded inside the key thickness. Keys can be credit-card shaped or key-ring shaped. One of the features of proximity key/reader pairs is the key reading distance, which depends on the installation and, more rarely, on the level of ambient electromagnetic noise. Technically-speaking, the key reader emits an electromagnetic wave through space to query one or several remote receivers or a key. Three types of key exist: passive, active or semi-passive. These different types are differentiated by the way the receiver is powered.
