Adaptive switchable FM/DAB windscreen antenna matched with a high-impedance amplifier

For the existing audio broadcast services FM and DAB (VHF-band), a new adaptive switchable windscreen antenna is presented for antenna diversity. Depending on the switching status, the antenna yields various versions of advantageous and well-established windscreen antenna structures. In order to deal with the different occurring antenna impedances, the adaptive antenna is connected to a special high-impedance amplifier and the results of the frequency responses are shown. By appropriate design of the filter network between the two stages of the amplifier the diverse frequency responses of the active antenna structures can be smoothed. In contrast to standard 50-Ohm amplifiers, which are very restricted regarding possible antenna impedances, it is possible to apply just one single high-impedance amplifier for car antenna structures with varying impedance behavior, as long as just a few conditions are met. This results in a lean and effective interface between the active windscreen antenna and the radio.