Micro-ray communication

A short historical review of the evolution of wireless communication is given. The method of generation and modulation of micro-rays around 17 cm with a tube having two grid lead-outs is discussed, and it is argued that the grid itself becomes a transmission line of negative leakance. Some experiments with ebonite lenses and zone plates are described. Paraboloidal mirrors, echelon gratings, and hemispherical mirrors, are discussed.The micro-ray equipments used on the commercial Lympne—St. Inglevert and the experimental Escalles—St. Margaret's links are described. Propagation measurements on these last two links are detailed and it is shown that, although there is an optical path in each case, severe fading, which is different on different wavelengths, sometimes takes place. This fading is attributed to an interference pattern which varies with atmospheric and tidal changes.The directivity and gain of paraboloidal mirrors and echelon gratings, as determined by experiment, are given.In conclusion, future possible uses of micro-rays are sketched.