Protective sleeve to protect electronic key has material which is opaque for excitation signal and excitation signal transmitted in different wavelength range from identification signal

摘要

A protective sleeve to protect an electronic key (1) which is equipped with a receiver unit for receiving an excitation signal sent out from the car for contact-free unlocking of a car and a transmitter unit to transmit an identification signal upon reception of the excitation signal, is described. To prevent the transmission of an identification signal (14) the protective sleeve (15) consists of a material which is opaque for the excitation signal (13). The excitation signal is transmitted in a different wavelength range from the identification signal. The protective sleeve consists of a material with metal-containing fabric that is opaque for radio waves in the wavelength range of the excitation signal.