(i) In year 1865, Maxwell predicted the electromagnetic waves theoretically. According to him, an accelerated charge sets up a magnetic field in its neighborhood.

(ii) In 1887, Hertz produced and detected electromagnetic waves experimentally at wavelength of about 6m.

(iii) Seven year later, J.C. Bose became successful in producing electromagnetic waves of wavelength in the range 5 mm to 25 mm.

(iv) In 1896, Marconi discovered that if one of the spark gap terminals is connected to an antenna and the other terminal is earthed, the electromagnetic waves radiated could go upto several kilometers.

(v) The antenna and the earth wires form the two plates of a capacitor which radiates radio frequency waves. These waves could be received at a large distance by making use of an antenna earth system as detector.

(vi) Using these arrangments; in 1899 Marconi first established wireless communication across the English channel i.e.across a distance of about 50 km.

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