Frequency-independent antenna concepts for the use in vehicles

This paper presents two different types of spiral antennas, which are suitable for the integration into vehicles. The antennas have to cover radio services such as communication, navigation and broadcasting services from 470 MHz up to over 2.3 GHz. One antenna concept is based on realizing the antenna as an on-glass antenna. As the antenna has to be completely planar, a special external feeding technique is necessary. The second concept is based on placing the antenna on the car's conducting bodywork. A cavity optimizes the radiation pattern and suppresses backradiation into the vehicle's interior. The performances of both antennas are discussed.