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Wednesday, November 23, 2016

Tribute to radio and microwave optics pioneer - Sir Jagadish Chandra Bose.


Sir Jagadish Chandra Bose,(30 November 1858 – 23 November 1937) was a polymath, physicist, biologist, biophysicist, botanist and archaeologist, as well as an early writer of science fiction. Living in British India, he pioneered the investigation of radio and microwave optics, made very significant contributions to plant science, and laid the foundations of experimental science in the Indian subcontinent.IEEE named him one of the fathers of radio science. He is considered the father of Bengali science fiction. He also invented the crescograph. A crater on the moon has been named in his honour.

Born in Munshiganj, Bengal Presidency during the British Raj, Bose graduated from St. Xavier's College, Calcutta. He then went to the University of London to study medicine, but could not pursue studies in medicine because of health problems. Instead, he conducted his research with the Nobel Laureate Lord Rayleigh at Cambridge and returned to India. He then joined the Presidency College of University of Calcutta as a Professor of Physics. There, despite racial discrimination and a lack of funding and equipment, Bose carried on his scientific research. He made remarkable progress in his research of remote wireless signalling and was the first to use semiconductor junctions to detect radio signals. However, instead of trying to gain commercial benefit from this invention, Bose made his inventions public in order to allow others to further develop his research.

Bose subsequently made a number of pioneering discoveries in plant physiology. He used his own invention, the crescograph, to measure plant response to various stimuli, and thereby scientifically proved parallelism between animal and plant tissues. Although Bose filed for a patent for one of his inventions because of peer pressure, his reluctance to any form of patenting was well known. To facilitate his research, he constructed automatic recorders capable of registering extremely slight movements; these instruments produced some striking results, such as Bose's demonstration of an apparent power of feeling in plants, exemplified by the quivering of injured plants. His books include Response in the Living and Non-Living (1902) and The Nervous Mechanism of Plants (1926).

The Scottish theoretical physicist James Clerk Maxwell mathematically predicted the existence of electromagnetic radiation of diverse wavelengths, but he died in 1879 before his prediction was experimentally verified. Between 1886 and 1888 German physicist Heinrich Hertz published the results of his experiments that showed the existence of electromagnetic waves in free space. Subsequently, British physicist Oliver Lodge, who had also been researching electromagnetic, conducted a commemorative lecture in August 1894 (after Hertz's death) on the quasi optical nature of "Hertzian waves" (radio waves) and demonstrated their similarity to light and vision including reflection and transmission at distances up to 50 metres. Lodge's work was published in book form and 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.
Bose's 60 GHz microwave apparatus at the Bose Institute,
Kolkata, India. His receiver (left) used a galenacrystal
detector inside a horn antenna and galvanometer to
detect microwaves. Bose invented the crystal radio detector,
waveguide, horn antenna, and other apparatus used at
microwave frequencies.
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."
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.
Diagram of microwave receiver and 

transmitter apparatus, from Bose's 
1897 paper
Bose went to London on a lecture tour in 1896 and met Italian inventor Guglielmo Marconi, who had been developing a radio wavewireless telegraphy system for over a year and was trying to market it to the British post service. 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' work in radio microwave optics was specifically directed towards studying the nature of the phenomenon and was not an attempt to develop radio into a communication medium. His experiments took place during this same period (from late 1894 on) when Guglielmo Marconi was making breakthroughs on a radio system specifically designed for wireless telegraphy and others were finding practical applications for radio waves, such as Russian physicist Alexander Stepanovich Popov radio wave base lightning detector, also inspired by Lodge's experiment. Although Bose's work was not related to communication he, like Lodge and other laboratory experimenters, probably had an influence on other inventors trying to develop radio as communications medium.

Bose 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. In fact, further work at millimetre wavelengths was almost non-existent for the following 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, especially 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. In fact, he had anticipated the existence of P-type and N-type semiconductors."

PB Parivar salute this great Indian Scientist and offer tribute on his 79th death anniversary. 


Credit and Source :- https://en.wikipedia.org/wiki/Jagadish_Chandra_Bose

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