Radio Inventors – J.C. Bose

With acknowledgements to both the SWLing Post and Hackaday for this. I have to admit, the only Bose I have heard of connected with electronics/radio is the American company who flamboyantly advertise the amazing properties of their equipment.

The gentleman who is the subject of this piece was an Indian scientist active at the turn of the 19th century. Marconi may have commercialised the use of radio, but it would appear J.C. Bose invented it way before. Anyway, here’s the article, I hope you enjoy it as much as I did.

The early days of electricity appear to have been a cutthroat time. While academics were busy uncovering the mysteries of electromagnetism, bands of entrepreneurs were waiting to pounce on the pure science and engineer solutions to problems that didn’t even exist yet, but could no doubt turn into profitable ventures. We’ve all heard of the epic battles between Edison and Tesla and Westinghouse, and even with the benefit of more than a century of hindsight it’s hard to tell who did what to whom. But another conflict was brewing at the turn of 19th century, this time between an Indian polymath and an Italian nobleman, and it would determine who got credit for laying the foundations for the key technology of the 20th century – radio.

Appointment and Disappointment

Jagadish_Chandra_Bose
Jagadish Chandra Bose

In 1885, a 27-year old Jagadish Chandra Bose returned to his native India from England, where he had been studying natural science at Cambridge. Originally sent there to study medicine, Bose had withdrawn due to ill-health exacerbated by the disagreeable aroma of the dissection rooms. Instead, Bose returned with a collection of degrees in multiple disciplines and a letter of introduction that prompted the Viceroy of India to request an appointment for him at Presidency College in Kolkata (Calcutta). One did not refuse a viceroy’s request, and despite protests by the college administration, Bose was appointed professor of physics.

Sadly, the administration found ways to even the score, chiefly by not providing Bose with any laboratory space, but also by offering him only 100 rupees a month salary, half of what an Indian professor would normally make, and only a third of an Englishman’s salary. Bose protested the latter by refusing salary checks – after three years his protest worked and he got his full salary retroactively – and worked around the former by converting a tiny cubicle next to a restroom into a lab. But in those 24 square feet, equipped with instruments of his own design and paid for at his expense, Bose would work wonders and begin to engineer the embryonic field of radio.

At around the time Bose joined Presidency College, Heinrich Hertz was confirming the existence of electromagnetic waves, postulated by James Clerk Maxwell in the 1860s. Maxwell died before he could demonstrate that electricity, magnetism, and light are all one in the same phenomenon, but Hertz and his spark gap transmitters and receivers proved it. Inspired by this work and intrigued by the idea that “Hertzian Waves” and visible light were the same thing, Bose set about exploring this new field.

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Bose’s microwave apparatus. Transmitter on right, galena detector in the horn on the left of the experiment stage. By Biswarup Ganguly

By 1895, barely a year after starting his research, Bose made the first public demonstration of radio waves in the Kolkata town hall. Details of the apparatus used are vague, but at a distance of 75 feet, he remotely rang an electric bell and ignited a small charge of gunpowder. The invited guests were amazed by the demonstration that Adrisya Alok, or “Invisible Light” as Bose would summarize it in a later essay, could pass through walls, doors, and in a particularly daring feat of showmanship, through the body of the Lieutenant Governor of Bengal.

Bose’s wireless demonstration was remarkable for a couple of reasons. First, it took place two years before Marconi’s first public demonstrations of wireless telegraphy in England. Where Marconi was keenly interested in commercializing radio, Bose’s interest was purely academic; in fact, Bose flatly refused to patent nearly all of the inventions that would spring from his tiny workshop, on the principle that ideas should be shared freely.

The 1895 demonstration also used microwave signals instead of the low and medium frequency waves that Marconi and others were working with. Bose recognized early on that shorter wavelengths would make it easier to explore the properties of radio waves that were similar to light, like reflection, refraction, and polarization. To do so, he invented almost all the basic components of microwave systems – waveguides, polarizers, horn antennas, dielectric lenses, parabolic reflectors, and attenuators. His spark-gap transmitters were capable of 60GHz operation.

Coherent Thoughts

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Marconi Admiralty Pattern Coherer. Source: The Science Museum (UK)

Some of Bose’s most important work in radio concerned detection of electromagnetic waves. Early wireless pioneers had discovered that electromagnetic waves could be rectified by fine metal particles contained in a tube between metal conductors; the electrical energy would cause the particles to clump together and become conductive. The device was called a coherer because of the clumping action and was used as rectifiers in all the early practical wireless receivers, despite its operation being not well-understood. Experiments with coherers continue to this day.

Early coherers had a problem, though – the filings stayed stuck together after the signal had passed. The device needed to be reset by a tiny electromagnetic tapping mechanism that jiggled the filings back into a non-conductive state before the next signal could be detected. This had obvious effects on bandwidth, so the search for better detectors was on. One improvement invented by Bose in 1899 was the iron-mercury-iron coherer, with a pool of mercury in a small metal cup. A film of insulating oil covered the mercury, and an iron disc penetrated the oil but did not make contact with the liquid mercury. RF energy would break down the insulating oil and conduct, with the advantage of not needing a decoherer to reset the system.

Bose’s improved coherer design would miraculously appear in Marconi’s transatlantic wireless receiver two years later. The circumstances are somewhat shady – Marconi’s story about how he came up with the design varied over time, and there were reports that Bose’s circuit designs were stolen from a London hotel room while he was presenting his work. In any case, Bose was not interested in commercializing his invention, which Marconi would go on to patent himself.

The Father of Semiconductors?

Early Bose galena point-contact detectors. Source: National Radio Astronomy Observatory
Early Bose galena point-contact detectors. Source: National Radio Astronomy Observatory

Bose also did early work in semiconductor detectors. Bose was exploring the optical properties of radio waves when he discovered that galena, an ore of lead rich in lead sulfide, was able to selectively conduct in the presence of radio waves. He was able to demonstrate that point contacts on galena crystals worked as a better coherer, and in an uncharacteristic move actually patented the invention. Interestingly, the patent includes descriptions of substances that show either decreased or increased resistance to current flow with increasing voltage; Bose chose to describe these a “positive” and “negative” substances, an early example of the “P-N” nomenclature that would become common in semiconductor research. Decades later, William Brattain, co-inventor of the transistor, would acknowledge that Bose had beat everyone to the punch on semiconductors and would credit him with inventing the first semiconductor rectifier.

Inventions and innovations would flow from Bose’s fertile mind for many decades. He eventually turned his attention to plant physiology, studying the stress responses of plants with a sensitive device he invented, the crescograph, which could amplify the movements of the tips of plants by a factor of 10,000. Not surprisingly, he also did important work on the effects of microwaves on plant tissues. Bose also did work comparing metal fatigue and fatigue in physically stressed plant tissues. Bose is also considered the father of Bengali science fiction.

Bose is rarely remembered as a pioneer in radio, despite all he accomplished in engineering the wireless system that would eventually stitch together the world. Given his position on patents, that’s not surprising – his inventions were his gift to the world, and he seemed content with letting others capitalize on his genius.

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