GB1324180A - Vehicle communication systems - Google Patents

Abstract

1324180 Radio signalling; aerials SUMITOMO ELECTRIC INDUSTRIES Ltd 30 Dec 1970 61741/70 Headings H4A and H4L A vehicle wireless communication system comprises a leaky coaxial cable 1, Fig. 6, which is installed along a vehicle track, and which has in its outer conductor an array of slots which are located in periodic fashion along its axis. The system also comprises a leaky coaxial cable type vehicle aerial 18 which has in its outer conductor an array of slots which are substantially in accord with the array of the cable 1 as regards configuration and periodicity. The waveguide to free space wavelength ratio of the aerial 18 is made to conform with that of cable 1, dielectric material being interposed if necessary between the inner and outer conductors of this aerial. The directivities of the aerial 18 and of the cable 1 are substantially the same, as is indicated by the lines 2. A transmitter or receiver 17 is connected to the cable 1, and a receiver or transmitter 19 is connected to the aerial 18, and dummy loads 20 are provided. In one embodiment the outer conductor of the aerial is circular in cross-section and has an array of slots which are alternately tilted to the right and to the left, dielectric material being provided between the inner and outer conductors (Figs. 3(a), 3(b), not shown). In a second embodiment the aerial has an inner conductor of strip form which is supported on a bar of dielectric material inside an outer conductor of rectangular cross-section. One broad face of the outer conductor is extended to overlap the side faces, and slots are cut therein (Figs. 4(a), 4(b), not shown). In a third embodiment, an inner conductor 15, Fig. 5, is of strip form, and is sandwiched between dielectric strips 16 and outer conductor strips 13, 14. Slots 10 are provided in the outer conductor strip 13.