Layout of GPS Antennas on an Automobile

Hironobu Sugimoto, Atsushi Watanabe, Tomio Yasuda, Yuuichi Murakami, Harumasa Hojo, Shigeo Kawashima, and Katsuo Yui

Abstract:	Recently, automobile navigation systems have become popular in Japan. For an automobile navigation system, position data is currently obtained by a dead reckoning method which uses an odometer for distance and a flux gate compass or an optical fiber gyro for direction. Cummulative position error has been a major problem to get accurate position with such a system. GPS is being introduced as an absolute position sensor to minimize this error. At first, it was popular to install a GPS antenna on the roof of an automobile, because the position fix availability by using one antenna is enough for automobile navigation, and in general the roof is the most effective location for an antenna to receive GPS signals. But, there are the following problems when an antenna is installed on the roof: 1) There is degradation of car’s shape. 2) There is no protection from theft or from damage by vandalism. 3) It is impossible to camouflage a special car which carries money and VIP as a normal car because an antenna is visible on the roof. So, the demand for installing an antenna at a location other than the roof is increasing. But, if an antenna is not installed on the roof, there is a possibility that the position fix availability becomes low because some GPS signals are masked by obstacles around the antenna. To solve the above problems without deterioration of position fix availability, it is useful to examine the layout of antennas in addition to using multiple antennas. In this paper, the effect of radiation pat tern, number and layout of antennas on the position fix availability are examined and a dual hidden-antenna GPS receiver is shown as an example for a commercial car. We believe that this layout examination of antennas is effective for automobile navigation systems.
Published in:	Proceedings of the 6th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1993) September 22 - 24, 1993 Salt Palace Convention Center Salt Lake City, UT
Pages:	1615 - 1622
Cite this article:	Sugimoto, Hironobu, Watanabe, Atsushi, Yasuda, Tomio, Murakami, Yuuichi, Hojo, Harumasa, Kawashima, Shigeo, Yui, Katsuo, "Layout of GPS Antennas on an Automobile," Proceedings of the 6th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1993), Salt Lake City, UT, September 1993, pp. 1615-1622.
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