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The new Satellite Digital Audio Radio Service (SDARS) has already started in USA. The circularly polarized satellite signals are supported by terrestrial transmitters in built-up areas using vertical polarization [1]. Therefore the receiving antenna has to meet both requirements. Due to automotive aspects for reception of this service low profile antennas are required. In this paper such an antenna is presented which meets both the SDARS-specifications and the requirements for SDARS-antenna diversity application due to multipath reception even with satellite signals. The design principle allows in a further up-grading multiband application for cellular phone e.g. GSM or UMTS.

According to the challenging antenna performance requirements for the reception of the Satellite Digital Audio Radio Services (SDARS), environmental influences are playing an important role for the practical design and application of such an antenna. This paper will report about remarkable influences on the performance of SDARS - Antennas with respect to ground plane conditions for measurements in anechoic chambers, as well as for vehicle mounting conditions. Results of field tests will show, what this means for reception.

The most challenging task for digital mobile satellite broadcast reception is to satisfy a variety of combined requirements for automotive applications. According to the US satellite digital broadcast system (SDARS) the antenna parameters according to the SDARS-Antenna Specification have to be met [1]. There is a great desire for a low profile design or even hidden antenna systems according to styling conditions given by the Automotive Industry. For the time being there are strong recommendations for a specific mounting location of a SDARS-antenna in order to meet the required radiation pattern on a vehicle. For many vehicle models this location is considered as inconvenient and there is a strong demand to design more inconspicuous antennas.

The principle of inconspicuous active window antennas is highly suitable for mobile application. Antennas of this kind form a necessary basis for a multi antenna diversity system on a car. The presented mobile multi antenna scanning diversity system highly improves the broadcast reception. The FM diversity system is optimized by application of an extremely fast operating FM diversity processor being available as integrated circuit now and being sensitive to noise, multipath distortion, cochannel-, adjacent channel- and intermodulation interference. The experiences, a german car producer has made with these systems in the late years in series production, are very positive and encouraging for implementation of these systems in future car models. Even a TV diversity system operating independently for picture and sound using different criterions is now under test.

The application of smart or intelligent antennas at base stations of cellular radio systems has been proven to be a successful way to enhance the performance and the channel capacity of personal communication systems. In contrast to those technically highly developed base station antennas, the appearance and the functional principle of car antennas with omnidirectional pattern has been almost the same during the last few years. This paper presents a new type of mobile phone car antenna, which is implemented as a phased array of multiple short antennas with optimum omnidirectional pattern. In addition, it will allow adaptive beam steering as well. Optimum reception can be achieved by using the same set of antennas in diversity mode. In spite of the comparatively low technical effort and the small dimensions this highly effective antenna configuration opens the possibility for smart antenna application in vehicles as well.