Radio, also known as radio broadcasting, is a technology for transmitting information using modulated electromagnetic waves with frequencies lower than that of light, known as radio waves.
History of Radio and Broadcasting Technology
Diagram of Radio Waves and Electromagnetic Waves
Radio waves are a type of electromagnetic radiation with a longer wavelength than infrared light, with frequencies ranging from 3 kHz to 300 GHz. Radio waves travel at the speed of light and occur naturally from phenomena such as lightning.
The term radio is also used to refer to a radio receiver, an electronic device used to receive modulated sound waves via antennas to amplify, restore to its original sound form, and output through speakers.
The Beginning with Electromagnetism …
In the early 19th century, numerous experiments were conducted to study the relationship between electricity and magnetism. Notably, in 1800, Alessandro Volta developed methods for generating electric current. Following him, Gian Domenico Romagnosi researched the connection between electric current and magnetism, but his work was not recognized.
It wasn’t until 1829 that Hans Christian Ørsted conducted an experiment demonstrating the magnetic property of electric current, where the current running through a coil deflected a nearby compass needle. Ørsted’s experiment sparked André-Marie Ampère to develop the theory of electromagnetism, followed by Francesco Zantedeschi, who researched the relationship between light, electricity, and magnetic fields.
Hans Christian Ørsted’s Experiment
In 1831, Michael Faraday conducted a series of experiments to prove the existence of electromagnetic induction. He formulated this relationship into a mathematical model known as Faraday’s law, which states that electromagnetic forces can propagate through the surrounding space of conductors.
Based on earlier research, Joseph Henry conducted an experiment proving that magnetic force could act from a height of 61 meters in 1832. He was also the first to create alternating current oscillating at high frequencies. In his experiments, he discovered that alternating current would generate oscillating forces that gradually decreased in frequency until returning to a state of equilibrium.
… to the Electromagnetic Wave Theory:
James Clerk Maxwell (1831-1879), Father of Electromagnetic Wave Theory.
From 1861 to 1865, building on the research of Faraday and other scientists, James Clerk Maxwell developed a theory known as the electromagnetic wave theory, published in the Royal Society journal under the title “On the Dynamics of the Electric Field“. He unified the major concepts of modern physics: electricity, magnetism, and light through his famous four Maxwell equations. Although he did not invent radio waves, his theory laid a solid foundation for the emergence of radio waves and radio transmitters as we know them today.
Early Radio Instruments:
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Mahlon Loomis and Experiment Sketch in 1866.
In 1866, Mahlon Loomis, an American dentist, conducted an experiment to demonstrate the concept of “wireless telegraphy.” In his experiment, he used two kites flown in the air. On the string of the first kite, he attached an electric meter, while the string of the other kite was fitted with an inductor coil. The results showed that the magnetic field from the second coil affected the electric meter on the string of the first kite. This marked the first successful case of wireless signal transmission through the air. Twenty years later, the famous German physicist Heinrich Rudolph Hertz further demonstrated that rapidly changing currents could be transmitted through space as radio waves similar to light and heat.
The First Radio Signals:
Guglielmo Marconi, an Italian inventor, proved the feasibility of transmitting information wirelessly through space. He successfully sent and received the first radio signals in 1895. In the early 20th century, Marconi began investing in an idea to transmit signals across the Atlantic Ocean to compete with cable telegraphy. In 1901, he sent the first wireless signal across the ocean from Poldhu, Cornwall—located in the southwest of England—to Signal Hill in St. John’s, Newfoundland, now part of Canada. The distance between the two points was approximately 3,500 km. The response signal Marconi received was three clicks, corresponding to the letter S in Morse code. In 1909, Marconi and Karl Ferdinand Braun were jointly awarded the Nobel Prize in Physics for their “contributions of great significance to the development of wireless telegraphy.”
Electrical Engineer/Inventor Guglielmo Marconi (1874-1937) with his first transatlantic wireless communication system in the UK in 1901.
In addition to Marconi, his contemporaries Nikola Tesla and Nathan Stufflefield also received patents for radio transmitters in the United States.
Development and Refinement Stage:
The messages transmitted via radio waves were similar to long-short signals (Morse code). In the early days, the signal transmitter was called “spark-gap machines.” It was developed to guide ships during docking or to maintain communication between ships. This was a method of signal transmission between two points, but it was not the radio device we recognize today.
Image of Marconi’s first 230kW “spark-gap machine.” The characters cast on the machine are W MACKIE & C, 47 1/2 OLD ST, LONDON EC.
The method of wireless communication using radio waves proved effective in rescue operations during disasters. These wireless signaling devices were installed on several ships. In 1899, the United States Navy established a wireless communication network among lighthouses off the coast of Fire Island, New York. Two years later, the U.S. Navy officially implemented this wireless radio communication system in the military, used alongside visual signaling methods and communication via carrier pigeons.
Image of the radio station in Hawaii in 1901. (Source: radiomarine.org)
In 1901, a wireless telegraphy service was established among five islands of the Hawaiian archipelago. In 1903, Marconi’s station in Wellfleet, Massachusetts sent a welcoming message from President Theodore Roosevelt to King Edward VII of Britain. In 1905, reports of the naval battle at Port Arthur during the Russo-Japanese War were transmitted via wireless telegraphy, and in 1906, the U.S. Weather Bureau adopted this method to improve the speed of weather forecast communications.
The famous telegram between President Theodore Roosevelt and King Edward VII in 1903.
(Source: royal.co.uk)
In 1910, Marconi launched a wireless telegraph service between the United States and Europe. A few months later, this service helped capture a murderer who had escaped from England, right at sea. By 1912, the first radio telegraph service across the Pacific Ocean was established between San Francisco and Hawaii.
Lee De Forest – The Father of Radio:
The development of radio communication in other countries was relatively slow due to the high manufacturing costs of early transmitters, as well as instability in the electrical systems and discharge currents between electrodes. However, the high-frequency generator developed by Alexanderson and the vacuum Triode tube invented by De Forest addressed most of these initial shortcomings.
Lee DeForest and his invention of the three-legged triode.
(Photo taken around 1914 to 1932, source: Wikipedia)
Lee De Forest invented the telegraphy system in space using the Triode amplifier and Audion (three-electrode lamp). In the 1900s, the development of radio technology reached a new milestone with the discovery of electromagnetic radiation, which was made by Lee De Forest himself. This radiation could amplify the radio frequency signals transmitted by antennas before being received by a detector. The transmitted signals had stronger intensity than before. De Forest was also the first to name this amplification system “Radio Station.”
De Forest’s AM Radio Broadcasting System. (Photo taken around 1916, source: Wikipedia)
De Forest’s invention was the amplitude modulation (AM) system, which allowed signals to be transmitted to multiple stations, unlike the previous spark-gap transmission method that only allowed communication between two points. This was the foundation of modern radio broadcasting technology, of which De Forest is considered the father.
Military Applications and Control Period:
When the United States entered World War I, all radio stations in the country were controlled by the military to prevent enemy spies from using them to transmit information. The U.S. government also took control of all patents related to this radio technology.
In 1919, after the government lifted the restrictions on these patents, the Radio Corporation of America (RCA) was established to manage the distribution and application of radio-related patents that had been restricted during the war.
The First Radio Voice:
The transmission of human voice over the radio still remains a debated topic. Some argue that the first recognized voice was “Hello Rainey” by Nathan B. Stubblefield, spoken to his collaborator in Murray, Kentucky, in 1892. Others claim the first radio voice belonged to Reginald A. Fessenden during a test conversation in 1906, which was heard by a radio device on ships hundreds of miles away.
Reginald A. Fessenden and his broadcasting system.
The Canadian inventor, Reginald A. Fessenden, is also known for inventing amplitude modulation and the echo sounder. Fessenden was a chemist who worked for Thomas Edison in the 1880s. He later established his own company and invented the radio frequency modulation method based on the “heterodyne principle”, enabling signal transmission in the air without interference.
The Birth of “Proper” Broadcasting Programs:
Photo of the NAA Radio Station in Arlington in 1917. (Source: virhistory)
In 1915, the first voice was transmitted by the Navy’s NAA in Arlington, Virginia, across the continent from New York to San Francisco, crossing the Atlantic Ocean to the Eiffel Tower in Paris. On November 2, 1920, KDKA Radio in Pittsburgh broadcast the results of the Harding-Cox election and started a daily radio program.
In 1927, a radio communication system connecting North America and Europe was established, and three years later, it was expanded to connect South America. By 1935, the first global calls were made, utilizing both wired and wireless radio systems.
The Emergence of FM Waves and Modern Radio:
In 1933, Edwin Howard Armstrong invented frequency-modulated radio (FM radio). FM waves have the advantage of minimizing interference from other electronic devices and the Earth’s magnetic field. By 1936, all transatlantic telephone communications from the U.S. to England and Paris adopted this method. At that time, a network of both wired and wireless communications connected the U.S. to nearly 187 other points abroad.
Howard and the first FM radio receiver on his honeymoon with his wife. (Photo taken in 1923, source: world.std)
Since then, wireless technology has developed rapidly. In 1947, scientists at Bell Labs in New Jersey, USA, invented the transistor. By 1954, Tokyo Telecommunications Engineering Corp, the predecessor of Sony, became the first company to produce portable transistor radios.
Sony’s first transistor radio (Source: xtimeline)
In 1965, the world’s first FM broadcasting antenna system was built on the Empire State Building in New York, allowing private FM stations to broadcast from one source to multiple receivers simultaneously. This model of radio broadcasting has been widely adopted worldwide to this day.
Details of the first FM broadcasting antenna on top of the Empire State Building
(Photo taken around 1965, source: lnl.com)
Conclusion
Thus, from the earliest research on electromagnetic wave theory to the rudimentary signals like an “S” character in Morse code or a simple “hello” transmitted between two points, we now have a multitude of modern radio stations offering rich and diverse news, current affairs, and entertainment programs.
Behind all these successes lies the endless efforts of scientists and inventors who transformed the impossible into reality, turning wired communication into wireless. This has created convenience and numerous applications for wireless signal transmission across various fields.
