MOBILE RADIO COMMUNICATION SYSTEM

• US 3,593,143 A
• Filed: 11/15/1968
• Issued: 07/13/1971
• Est. Priority Date: 11/17/1967
• Status: Expired due to Term

• Current Assignee: Kitani Hiroshi, Nakahara Tsuneo
• Original Assignee: Kitani Hiroshi, Nakahara Tsuneo
• Inventors: NAKAHARA TSUNEO, KITANI HIROSHI
• Application Number:
  US04/776,100
• Time in Patent Office: 970 Days
• US Class Current: 455/39
• CPC Class Codes: H01Q 13/20 Non-resonant leaky-waveguide or transmission-line antennas; Equivalent structures causing radiation along the transmission path of a guided wave
• CPC Class Codes: H04B 5/28 using the near field of leaky cables, e.g. of leaky coaxial cables

Abstract

A mobile radio communication system operating between a moving train and a stationary land station comprises a leaky waveguide or the like which is partly opened by providing a plurality of perforations or slits and a controlling device distributed along the waveguide or the like so that the electromagnetic wave transmitted in the waveguide leaks out of the waveguide only at that portion where the train is progressing. The controlling device may comprise a metallic cover to open or close the perforations or slits or matching elements which may vary the leakage impedance through the perforations or slits upon detection of the approaching train.

Claims

1. In a mobile radio communications system for a moving vehicle traveling a predescribed route including a leaky waveguide having a series of longitudinally spaced leakage perforations extending along said route and antenna means carried by said vehicle and operatively disposed with respect to said waveguide, the improvement comprising:

a plurality of individually movable covers disposed along said waveguide to cover respective perforations and means responsive to the movement of said vehicle relative to said waveguide to sequentially remove said covers in the immediate vicinity of said moving vehicle to allow wave transmission between the uncovered portion of said waveguide and said vehicle carried antenna means.

2. In a mobile radio communications system for a moving vehicle traveling a predescribed route including a leaky waveguide having a series of longitudinally spaced leakage perforations extending along said route and antenna means carried by said vehicle and operatively disposed with respect to said waveguide, the improvement comprising:

supporting means constituting a channel for the leaked electromagnetic wave energy, and variable impedance means carried by said supporting means for normally mismatching the impedance between portions of said system wave communication path to prevent leakage of wave energy between said waveguide and said moving vehicle antenna, and means for changing said variable impedance means in the immediate vicinity of said moving train to effect matching of the impedance at localized positions along said waveguide.

3. The mobile radio communications system as claimed in claim 2, wherein said variable impedance means comprises a varactor diode mounted interiorly of said supporting means and said means for operatively changing the impedance of said diode to match the impedance of a perforation viewed from the inside of said waveguide to the space impedance between said waveguide and said antenna, whereby wave energy is transmitted between the waveguide and the antenna means in the immediate vicinity of the moving vehicle.

4. The mobile radio communications system as claimed in claim 2, wherein said variable impedance means comprises a dielectric material block which is positioned in path of the wave within said supporting means, and wherein said means for changing the impedance thereof comprises means for changing the position of said dielectric material block to match the impedance of the perforation viewed from inside said waveguide to the space impedance between said moving vehicle antenna and said waveguide which leaks wave energy in the immediate vicinity of said moving vehicle.

5. The mobile radio communications system as claimed in claim 2, wherein said variable impedance means consists of a magnetic material block having inductive properties positioned in the path of the wave energy within said supporting means so as to effectively change the impedance of said channel and means for changing the position of said magnetic material block to match the impedance of said perforation viewed from inside said waveguide to the space impedance between said waveguide and said moving vehicle antenna which leaks the wave energy in the immediate vicinity of the moving vehicle.