Communications: radio wave antennas – Antennas – Measuring signal energy
Reexamination Certificate
1999-04-21
2001-10-02
Ho, Tan (Department: 2821)
Communications: radio wave antennas
Antennas
Measuring signal energy
C343S895000, C343S702000, C455S575100
Reexamination Certificate
active
06297780
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a mobile station (apparatus) for communication with a satellite.
2. Description of the Related Art
Generally, in a cellular mobile communication system, a service area is divided into a plurality of coverage areas defined by a plurality of base stations. Therefore, when a mobile station moves from one coverage area to another coverage area, a complex call connection control is required. In addition, large blind areas due to the locations of the base stations may be generated, so that a service interruption is created for the mobile stations. In order to dissolve such problems, a mobile satellite communication system where mobile stations can communicate with each other via one or more satellites has been developed.
In a mobile satellite communication system using a plurality of satellites, one satellite may have a relatively large elevation angle with respect to a mobile station, while another satellite may have a relatively small elevation angle with respect to that mobile station. In addition, the mobile station may be located in a blind area of some of the satellites due to buildings or the like. Therefore, a prior art mobile station (apparatus) adopts a single omnidirectional antenna.
In the above-mentioned prior art mobile apparatus, however, it is impossible that the single omnidirectional antenna can have a uniform directivity over an elevation angle of from 0° to 90°. Even if the single omnidirectional antenna establishes a broad directivity, the antenna gain is 0 dBi at most. Therefore, if the antenna gain is forced to be increased, a transmitter circuit (power amplifier) has to be increased in size, thus increasing the manufacturing cost as well as the power dissipation. If the power dissipation is significantly increses, the continuous operation time period of the mobile apparatus is remarkably reduced.
In a system other than in a mobile satellite communication system, note that antenna diversity technology using a plurality of antennas in a receiver side has been used. However, even if antenna diversity technology is applied to a transmitter side, since the frequency of the transmitter side is different from that of the receiver side and the characteristics of the transmitting and receiving antennas are different from each other, this antenna diversity technology is not suitable in the transmitting side.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a mobile apparatus capable of effectively carrying out communication with a satellite without increasing a transmitter circuit in size and power dissipation.
According to the present invention, in a mobile apparatus for communication with a satellite, a plurality of antennas having different directivities from each other are provided. A selector circuit is connected between a transmitter circuit and the antennas to select and connect one of the antennas to the transmitter circuit. A control section controls the selector circuit in accordance with a reflected power detected from one of the antennas.
REFERENCES:
patent: 5346300 (1994-09-01), Yamamoto et al.
patent: 5408690 (1995-04-01), Ishikawa et al.
patent: 5471146 (1995-11-01), Krayeski et al.
patent: 5574981 (1996-11-01), Ahonen
patent: 5754104 (1998-05-01), Saito
patent: 6021317 (2000-02-01), Irvin
patent: 6072441 (2000-06-01), Tanabe
patent: 6118409 (2000-09-01), Pietsch et al.
patent: 06164232 A (1994-06-01), None
patent: 7-87011 (1995-03-01), None
patent: 8-103039 (1996-04-01), None
patent: 9-27783 (1997-01-01), None
patent: 09223994 A (1997-08-01), None
Alemu Ephrem
Ho Tan
NEC Corporation
Sughrue Mion Zinn Macpeak & Seas, PLLC
LandOfFree
Mobile apparatus with plurality of antennas having different... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Mobile apparatus with plurality of antennas having different..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Mobile apparatus with plurality of antennas having different... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2605137