Medium-frequency radio broadcasting retransmission system for confined and electromagnetically shielded areas

• US 5,537,637 A
• Filed: 03/08/1994
• Issued: 07/16/1996
• Est. Priority Date: 09/21/1993
• Status: Expired due to Term

• Current Assignee: NHK Integrated Technology Inc. (Japan Broadcasting Corporation), Nippon Hoso Kyokai
• Original Assignee: NHK Integrated Technology Inc. (Japan Broadcasting Corporation), Nippon Hoso Kyokai
• Inventors: Fujiwara, Atsumi, Kitanda, Masaaki, Watanabe, Shinichi, Sugita, Tadao, Toyosawa, Tatehiko, Shoji, Kazumi
• Primary Examiner(s): Urban, Edward F.
• Application Number:
  US08/207,209
• Time in Patent Office: 861 Days
• Field of Search: 455/66, 455/55.1, 455/53.1, 455/108, 455/14, 455/280
• US Class Current: 455/14
• CPC Class Codes: H01Q 1/007 specially adapted for indoor communication
• CPC Class Codes: H04B 5/266 One coil at each side, e.g. with primary and secondary coils
• CPC Class Codes: H04H 20/80 having frequencies in two or more frequency bands, e.g. medium wave and VHF

Abstract

A medium-frequency radio transmission system is formed by installing a receiving antenna for receiving an amplitude-modulated medium-frequency radio wave at the rooftop of an existing building, receiving the medium-frequency radio wave, coupling the received medium-frequency radio wave to an existing distributing cable or distributing conductive piping with or without a coupler for the radio wave, and transmitting the radio wave to a predetermined floor. At the predetermined floor the basement or tunnel of an existing building such as underground shopping mall, underground parking lot, underground railway, road tunnel or deep space of massive building is provided with a coupling such as an existing loop-like or linear wiring or piping line with or without a coupler.

Claims

1. A system for transmitting a medium-frequency radio wave into a tunnel comprising:

a receiving antenna for receiving an amplitude-modulated medium-frequency radio wave at an upper portion of ground facilities;

a first booster connected to said antenna and comprising a phase shifter, a level regulator, and an impedance matching device for preventing oscillation;

a coupler connected to said booster and coupled with existing wiring or piping for coupling the received medium-frequency radio wave to existing wiring or piping, said existing wiring or piping transmitting the wave to a tunnel or a predetermined underground;

a second booster connected to said existing wiring or piping with an another coupler and comprising a phase-shifter, a level-regulator, and an impedance matching device for preventing oscillation; and

existing linear wiring or piping prepared within a tunnel of the predetermined underground for receiving the transmitted medium-frequency radio wave via said second booster, the second booster feeding the transmitted medium-frequency radio wave to a condenser, and said condenser feeding radio wave current to said existing linear wiring or piping wherein said existing linear wiring or piping is conductive, and the medium-frequency radio wave is reradiated from said existing linear wiring or piping.

2. A system for transmitting a medium-frequency radio wave into a tunnel as defined in claim 1, wherein said existing linear wiring or piping is not active, and the radio wave current is directly fed thereto without a condenser.

3. A system for transmitting a medium-frequency radio wave into a tunnel as defined in claim 1, wherein said coupler is a ferrite core surrounding a primary line and a secondary line.