A Cursory Historical Overview on the Evolution of Wireless Communications

Magdalena Salazar-Palma*, Senior Member, IEEE, and Tapan K. Sarkar**, Fellow, IEEE

*Signal Theory and Communications Department, Universidad Carlos III de Madrid, Spain, e-mail: [email protected] ** Electrical Engineering and Computer Science Department, Syracuse University, USA, e-mail: [email protected]

Abstract — This presentation offers a historical overview on also demonstrated that inductive loading of the circuit the evolution of field theory for wireless communications. improved its performance. In 1855 French engineer Jean- Index Terms — History, wireless, radio, communications. Mothée Gaugain studied the rectifying action between two metal balls in an evacuated chamber, producing the first I. INTRODUCTION Electric Valve. In 1861, Scottish physicist and mathematician, James Electricity and magnetism are as old as human civilization. Clerk Maxwell (Fig. 4), the father of electrical engineering, The Chinese navigated the Indian Ocean using magnetite wrote to British scientist Michael Faraday (Fig. 4), indicating floating on mercury, around 1000 BC. The Baghdad battery that he has vindicated his theory on action at a distance and have (Fig. 1) was radio carbon dated to 250 BC, long before the reached the conclusion that light was electromagnetic in nature Italian physicist Alessandro Giuseppe Antonio Anastasio using dimensional analysis. Maxwell could still be called the Count Volta (Fig. 1) constructed his pile in 1799. During the father of electrical engineering and the greatest scientist of the seventeen and the eighteen century a number of experiments last century even if he would have not done any work on and inventions were carried out by scientists all over the electromagnetic theory! He provided a general methodology world. They paved the way for the crucial discoveries of the nineteenth and twentieth century that made possible wireless (or radio) communications. Some of those discoveries are highlighted in this presentation.

Figure 1. Left: Baghdad battery. Right: Alessandro Volta. Figure 2. Left: Henry Cavendish. Right: Charles-Augustin de Coulomb.

II. SOME CRUCIAL EVENTS English chemist and physicist Sir Henry Cavendish (Fig. 2) discovered the inverse square law and even experimentally verified it 10 years before French physicist Charles-Augustin de Coulomb (Fig. 2) did and even anticipated the law derived by German physicist and mathematician Georg Simon Ohm (Fig. 3) which was compiled and published 100 years later. German scientist Munk A. Rosenshold discovered the semiconductor rectifying action over alternating current in 1835. According to USA Congress (HR269), the first demonstration of telephone was made by Antonio Santi Giuseppe Meucci (Fig. 3), at Havana, Cuba, in 1841 [1]. He Figure 3. Left: Georg Simon Ohm. Right: Antonio Meucci.

Interestingly, the same year in which Maxwell wrote his treatise, American dentist Mahlon Loomis (Fig. 6) wrote the earliest description of a wireless transmission system and generated the world’s first patent on Wireless Telegraphy. In 1882, a Kentucky melon farmer Naathan B. Stubblefield (Fig. 6), transmitted audio signals without wires.

Figure 4. Left: James Maxwell. Right: Michael Faraday. for the solution of Kirchoff’s laws as a ratio of two determinants, showed how a circuit containing both capacitance and inductance would respond when connected to generators containing alternating currents of different frequencies, thus developing the phenomenon of electrical resonance. He took the first color photograph using three separate pictures using red, green and blue, based exactly on Figure 6. Left: Mahlon Loomis. Right: Nathan Stubblefield. the same principles that modern television operates today, although his name is rarely mentioned [2]. He wrote the first In 1895 Russian inventor Alexander Stepanovich Popoff paper on control theory and introduced the firrst statistical law (Fig. 7) demonstrated his Thunderstorm Recorder using an in to physics, in addition to the concept of entropy and aerial, a coherer, and an electromagnetic relay and Italian ensemble averaging which is routinely used in signal electrical engineer Guglielmo Marconi (Fig. 7) transmitted processing and information theory. He compiled in 1864, his and received a coded message at a distance of 1.75 miles near concept of curl, gradient, divergence in his two volume Treatise his home at Bologna, Italy. The same year, Indian physicist on Electromagnetism which interestingly did not give any importance to the displacement current. He wrote 20 equations, but not the boundary conditions to solve them, and he used the wrong gauge, in addition. The modifications of those equations were first accomplished by German physicist Heinrich Rudolf Hertz (Fig. 5) around 1884, who wrote the fourr equations we use today into twelve equations in a scalar form. During the same time period, they were cast independently into the vector form, resulting into the four equations that we use today, by English physicist, mathematician, and electrical engineer Oliver Heaviside (Fig. 5), who did not have a formal college education! This is why Albert Einstein used to refer to the four equations as Maxwell-Heaviside-Hertz equations.

Figure 7. Left: Alexander Popoff. Right: Giuglielmo Marconi.

Sir Jagadis Chunder Bose (Fig. 8) generated and detected wireless signals of 6 mm wavelength. He produced a fantastic variety of devices and techniques: wave-guides, horn antenna, cut-off grating, dielectric lens, microwave reflectors, double- prism directional coupler, polarimeter, interferometer, dielectrometer, and so on. His waveguide connecting his device to a horn antenna intrigued his mentor, John William Strutt, 3rd Baron Rayleigh (Fig. 8), so much that he made a trip

to visit him and on his way back generated the first paper on Figure 5. Left: Hertz. Right: Heaviside. propagation through waveguides.

978-1-4673-1088-8/12/$31.00 ©2012 IEEE after Tesla’s death, the US Supreme Court upheld Tesla’s patent 645,576 for invention of Radio. The court had selfish reasons for doing so. Marconi Company was suing the American government for using its patents in World War I. The court simply avoided the action by resorting priority to Tesla’s patent over Marconi. In 1905 Slovak Catholic priest and inventor Jozef Murgas (Fig. 10) achieved radio transmission of information between Wilkes-Barre and Scranton, Pennsylvania (a distance of 20 miles or 30 km). Murgas invented the so called tone system which diminished

the time needed to deliver a signal and thus considerably Figure 8. Left: Sir Jagadis Chunder Bose. Right: Lord Rayleigh. improved the system.

Croatian-American electrical engineer Nicola Tesla (Fig. 9) demonstrated a radio controlled boat in Madison Square Gardens in 1896. Brazilian Catholic priest and inventor Father Roberto Landell de Moura (Fig. 9) was the first to accomplish the transmission of the human voice by a wireless machine that is, by irradiating an electromagnetic wave, modulated by an audio signal. He conducted his first public experiment on June 3, 1900. The same year Tesla obtained patents USP 645,576 and 649,621 on System of Transmission of Electrical Energy, submitted in 1897, which United States of America Supreme Court recognized to be the first patents on Radio. Marconi submitted his first US patent also in 1900. He continued to submit patents on Radio. They were all turned down. The same year Canadian-American physicist and Figure 10. Left: Reginald Fessenden. Right: Jozef Murgas. inventor Reginald Aubrey Fessenden (Fig. 10) did the first speech transmission (over 25 miles) using a spark transmitter. III. CONCLUSION Some of the crucial events up to 1905 have been highlighted. The aim of this presentation has been also to illustrate that simultaneous developments were going on all over the world and that each invention provided a solution to a portion of the puzzle. It is also quite interesting to observe that many of the key developments in wireless were made by researchers who had little formal education. Also Maxwell, who was a mathematician by training, wrote that he did not want to employ any mathematical principles until he went through all of Faraday’s experiments in order to understand first the physical phenomena involved. Thus, one other conclusion of this presentation could be that in our teaching we should first

provide the context and highlight the physical phenomena Figure 9. Left: Nicola Tesla. Right: Father de Moura. before going through all the mathematical details. Perhaps it is time for a change! By the early 1900s, Marconi has succeeded in transmitting wireless signals over large distances and thus he proved the REFERENCES contemporary scientific community to be wrong, as nobody [1] T. K. Sarkar, R. J. Mailloux, A. A. Oliner, M. Salazar-Palma, thought that wireless transmission over such long distances and D. L. Sengupta, History of Wireless, John Wiley & Sons – was possible. He succeeded for two reasons, first going to IEEE Press, Hoboken, NJ, USA, 2006. lower frequency, and second by connecting one end of his [2] T. K. Sarkar, M. Salazar-Palma, D. L. Sengupta, “Who Was tuning circuit to the earth and the other end to an aerial. In James Clerk Maxwell and What Was/Is His Electromagnetic 1904 the United States Patent Office reversed itself and gave Theory”, Feature article, IEEE AP Society website, http://www.ieeeaps.org/ . the Radio patent to Marconi. However, in 1943, two months