Hitachi-kokusai Electric Inc.

Kokusai Electric Co., Ltd.

Other

Mitsuru Muramoto

Kanemi Sasaki

Hirotaka Saito

Naoki Onishi

Kiyohiko Itoh

Yuji Aoyagi

Manabu Yamamoto

The present invention is to provide a radio system that enables effective reuse of a limited number of frequencies without the occurrence of interference between subscriber stations. In the radio system according to the present invention, each base station is divided into two or more sectors, each of which is provided with an antenna different in directivity on a horizontal plane. The antennas are so placed that the antenna beams cover all the directions on the horizontal plane as a whole, and all the antennas using the same frequency and polarized wave are so arranged to face in about the same direction.

Radio system

The cell expansion system and method maximize the use of communication signal resource such as frequencies and polarized waves in expanding base stations for wireless communication. The cell are divided into four equal sectors, and at least a pair of adjacent sectors of the adjacent cells shares a common signal for wirelessly communicating with each other.

Wireless communication system and method of maximizing the use of communication signal resource

Radio communication systems, e.g. cellular telephones, have employed a space diversity antenna system which includes a plurality of antennas. In the space diversity antenna system for use in the cellular telephone, since two antennas are positioned adjoining each other, the space diversity effect cannot be adequately provided. To solve this problem, the polarization diversity antenna system according to this invention incorporates a first antenna, a second antenna, and a conductive board on which the second antenna is fixed at a given position, thus preventing the current flowing in the conductive board from causing the reception characteristic of the second antenna to deteriorate.

Polarization diversity antenna system for cellular telephone

A slot array antenna with a cavity of a simple construction having a plurality of slots formed on a dielectric substrate and capable of providing good directional characteristics while minimizing inter-slots coupling. The slot array antenna ( ) includes a power supply line in the form of a micro-strip line formed on one surface of the dielectric substrate, a slot antenna portion ( ) with a plurality of slots ( ) formed on the other surface of the dielectric substrate in an array-like fashion so as to extend perpendicularly to the micro-strip line with the dielectric substrate interposed therebetween, and a reflector ( ) with a cavity ( ) having an opening disposed in opposition to a plane on which the plurality of slots ( exist). In this case, if the cavity has a width narrow enough to cut off a frequency of radio waves to be used, the directionality of the slot array antenna can be optimized.

Growing community of inventors

Tokyo, Japan

Mitsuru Muramoto