The use of satellite broadcasting (BS broadcasting) is greatly desired not only at home but also in automobiles. This is because the BS broadcasting has picture and sound qualities much higher than those of terrestrial broadcasting and covers th whole country on an identical channel. To receive BS broadcasting, however, an antenna with a high gain is necessary; then it has a sharp directivity. Consequently, a facility to precisely track a satellite is indispensable for an automotive BS receiving antenna system. It is also necessary to make the antenna system as small and low profile as possible in order to solve a problem for mounting. This paper reports the extremely small and high-performance BS receiving antenna system developed for mounting on compact cars. The antenna system measures 400 mm in diameter and 29 mm in height, which is extremely thin in comparison with conventional antenna systems. In order to complete the small size and the low profile, an annular ring microstrip antenna element, which is a basic component for receiving the radio wave, and a high-efficiency array antenna with a wide and tilt beam have been developed. In addition, the antenna structure became drastically simple by developing a feed probe which omits a conventional rotary joint and a direct drive mode which rotates the array antenna itself by a motor. Moreover, the results of a field experiment clarify that enough receiving performance is obtained by using the developed satellite tracking algorithm. �@
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