| 摘要 |
PROBLEM TO BE SOLVED: To obtain an antenna system that has an excellent reception gain over a desired range of angle of elevation without increasing volume, weight and cost in the system. SOLUTION: A circularly polarized wave generation feeding circuit 12 and a low noise amplifier LNA 13 are placed in a fixing jig 8. Furthermore, a plane antenna 10 and a ground conductor board 11 whose diameter is D are provided outside the fixing jig 8, a dielectric board 9a isolates the plane antenna 10 from the ground conductor board 11 and fix them, and a dielectric board 9b isolates the ground conductor board 11 from the fixing jig 8 and fix them respectively. Then a randome 6 covers them and the radome 6 is mounted on an automobile by a magnet 7 placed on a bottom of the radome 6. Then the plane antenna 10 is operated in a TM21 mode to produce a conical beam, and the diameter D of the ground conductor board 11 is selected to be 80-110 mm so as to obtain a sufficient reception gain from a direction of a satellite over a horizontal direction.
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