Jagadish Chandra Bose - Radio Research

Radio Research

The British theoretical physicist James Clerk Maxwell mathematically predicted the existence of electromagnetic waves of diverse wavelengths, but he died in 1879 before his prediction was experimentally verified. British physicist Oliver Lodge demonstrated the existence of Maxwell’s waves transmitted along wires in 1887–88. The German physicist Heinrich Hertz showed experimentally, in 1888, the existence of electromagnetic waves in free space. Subsequently, Lodge pursued Hertz’s work and delivered a commemorative lecture in June 1894 (after Hertz’s death) and published it in book form. Lodge’s work caught the attention of scientists in different countries including Bose in India.

The first remarkable aspect of Bose’s follow up microwave research was that he reduced the waves to the millimetre level (about 5 mm wavelength). He realised the disadvantages of long waves for studying their light-like properties.

In 1893, Nikola Tesla demonstrated the first public radio communication. One year later, during a November 1894 (or 1895) public demonstration at Town Hall of Kolkata, Bose ignited gunpowder and rang a bell at a distance using millimetre range wavelength microwaves. Lieutenant Governor Sir William Mackenzie witnessed Bose's demonstration in the Kolkata Town Hall. Bose wrote in a Bengali essay, Adrisya Alok (Invisible Light), “The invisible light can easily pass through brick walls, buildings etc. Therefore, messages can be transmitted by means of it without the mediation of wires.” In Russia, Popov performed similar experiments. In December 1895, Popov's records indicate that he hoped for distant signalling with radio waves.

Bose’s first scientific paper, “On polarisation of electric rays by double-refracting crystals” was communicated to the Asiatic Society of Bengal in May 1895, within a year of Lodge’s paper. His second paper was communicated to the Royal Society of London by Lord Rayleigh in October 1895. In December 1895, the London journal the Electrician (Vol. 36) published Bose’s paper, “On a new electro-polariscope”. At that time, the word ‘coherer’, coined by Lodge, was used in the English-speaking world for Hertzian wave receivers or detectors. The Electrician readily commented on Bose’s coherer. (December 1895). The Englishman (18 January 1896) quoted from the Electrician and commented as follows:

”Should Professor Bose succeed in perfecting and patenting his ‘Coherer’, we may in time see the whole system of coast lighting throughout the navigable world revolutionised by a Bengali scientist working single handed in our Presidency College Laboratory.”

Bose planned to “perfect his coherer” but never thought of patenting it.

In May 1897, two years after Bose's public demonstration in Kolkata, Guglielmo Marconi conducted his wireless signalling experiment on Salisbury Plain. Bose went to London on a lecture tour in 1896 and met Marconi, who was conducting wireless experiments for the British post office. In an interview, Bose expressed disinterest in commercial telegraphy and suggested others use his research work. In 1899, Bose announced the development of a "iron-mercury-iron coherer with telephone detector" in a paper presented at the Royal Society, London.

Bose's demonstration of remote wireless signalling has priority over Marconi. He was the first to use a semiconductor junction to detect radio waves, and he invented various now commonplace microwave components. In 1954, Pearson and Brattain gave priority to Bose for the use of a semi-conducting crystal as a detector of radio waves. Further work at millimetre wavelengths was almost non-existent for nearly 50 years. In 1897, Bose described to the Royal Institution in London his research carried out in Kolkata at millimetre wavelengths. He used waveguides, horn antennas, dielectric lenses, various polarisers and even semiconductors at frequencies as high as 60 GHz; much of his original equipment is still in existence, now at the Bose Institute in Kolkata. A 1.3 mm multi-beam receiver now in use on the NRAO 12 Metre Telescope, Arizona, US, incorporates concepts from his original 1897 papers.

Sir Nevill Mott, Nobel Laureate in 1977 for his own contributions to solid-state electronics, remarked that "J.C. Bose was at least 60 years ahead of his time" and "In fact, he had anticipated the existence of P-type and N-type semiconductors."