Fujikura Ltd.

  1. Home
  2. Products
  3. Leaky coaxial cables (LCX)


Leaky coaxial cables (LCX)

The Leaky coaxial cable is a kind of the coaxial cables, having the outer conductor with periodic slots, and the cable makes part of electric waves propagated through the cable radiate outside by these periodic slots.
The radiant electric field is almost the circular symmetry and can be utilized for the radio communication to moving objects. The generated electric field is confined to around the leaky coaxial cable, therefore the cable can be used very conveniently for the radio communication in the limited extent of roads, tunnels, areas along railways and underground roads etc.



  1. The Leaky Coaxial Cables are applicable to all radio communication to moving objects.
    The leaky coaxial cables are widely applicable not only the radio communication among railways and motorcars but also remote units and control units related to moving objects and portable wireless telephones.
  2. The radiant electric field is very high quality
    The change of the electric field along the leaky coaxial cable is extremely little, therefore the cable is very superior to other leaky lines, for example the parallel two lines etc. The radiant wave is made of the electric field, therefore the decrease of the field is in proportion to the square root of the distance. This is a very different point between the leaky coaxial cable and other leaky lines using the surface wave. Accordingly it is possible to do the radio communication in the leaky coaxial cable even if the antenna is installed more or less apart from the cable.
  3. THE Leaky Coaxial Cable is not affected by Pollution
    The electric field radiated by the surface wave is not used, therefore even if the surface of the leaky coaxial cable is more or less polluted, the decrease of the electric field is little. Therefore the maintenance of the cable be comes easier.
  4. The relay interval can be prolonged
    The grading is possible because the coupling loss between the transmission power in a leaky coaxial cable and the reception power in an antenna is freely changeable. Therefore the relay interval can be prolonged and the number of the relays can be lesser.
  5. The Leaky Coaxial Cable can be used as the combined line
    The leaky coaxial cable can not only be used over the wide frequency band but also be used in the low frequency band such as the rebroadcast in a middle wave with the outer conductor and earth or with the outer conductor and the messenger wire.


System Design

In order to make up for the loss of the signal transmitted through the leaky coaxial cabbies, the cable with the coupling quantity be coming larger in order are connected (grading). For example the level diagram in the case of grading is as follows.


  • The coupling loss is the proportion of the transmission signal strength in the leaky coaxial cable to the received wave by a standard dipole antenna at a distance of 1.5 meters from the cable, and is expressed in dB unit. Generally the coupling loss is from 50 dB to 80 dB.
  • The difference between the coupling loss of the adjacent leaky coaxial cables is called, the grading quantity. This value is generally about 10 dB.
  • When the propagated power is not sufficient in one grading section, the power supply unit is installed in the middle of the route and the power is supplied to both directions. And besides the relay units can be installed at reasonable places.
  • 50Ω N type connectors and a jumper wire are used for the connection between two leaky coaxial cables.
  • It is in some case necessary to adjust the phase of the signal transmitted through the leaky coaxial cable at the connective part. FUJIKURA Ltd. manufactures the leaky coaxial cables and besides can design and construct the above such systems, so please consult with FUJIKURA Ltd.