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The growth of radio in the 1920’s


The Amon N Andy Radio ShowWhen KDKA made their first radio broadcast in 1920, there were only a few thousand receivers around the United States. Within two years, the number of new radio stations surged as did the demand for radio receivers. The American way of life transcended to a culture where people held “radio parties” for friends to gather in each other’s homes to listen to popular radio shows. Youth began to dance to the latest jazz music and preachers broadcast their Sunday sermons to thousands of listeners. News shows, especially when important breaking news happened, became very popular with the public. Entertainment show resembling vaudeville stage shows, short skits, and live comedy acts became popular family entertainment. Radio became deeply integrated into American’s lives. Families began to schedule their day-to-day activities around popular radio shows.

By the late 1920’s, radio shows including westerns, detective shows, children’s shows, soap operas, romances, and comedies, grew more sophisticated with carefully orchestrated plots, lively dialog, and masterful soundtracks. The first serial program, a show with a plot that continued to build and develop from week to week, was Amos ‘n’ Andy. Debuting in 1929, the daily fifteen minute episodes centered around two African America characters who were stereotypically depicted as “buffoons”. Amos ‘n’ Andy was one of the most popular radio shows on the air.

As radio ownership grew, so did the number of transmitting stations. In January 1920, there were only four radio stations around the United States and only a handful more around the entire planet. By the end of 1922 there were six hundred radio stations the United States alone.

Chicago’s first station, KYW, was launched in 1921 by Westinghouse Electric and Manufacturing Company. At first KYW broadcasted only opera music setting a trend for focused, channeled content types. When the opera season ended, KYW began broadcasting popular music, classical music, sporting events, lectures, fictional stories, newscasts, weather reports, stock market updates, and political commentary. This broadcast content was local and transmitted only to Chicago area listeners. When NBC and CBS were founded in 1926 and 1927 respectively, radio programming became national and Americans from coast to coast heard the same shows. The two companies developed a massive following of listeners, setting the stage for the rise of two of the biggest entertainment companies in American history.

Finances and regulation – radio grows up

Early radio station in Houston, TexasIn the beginning, there was no government control over the radio frequencies that were used and broadcast over the airwaves nor was there federal oversight over radio stations themselves. Stations were free to broadcast however they liked. It was not uncommon for a listener’s program to be interrupted by another radio operator who chose to transmit over the same frequency. The governments did not want to be involved with the regulation of radio but public demand to end the free for all that radio had become, prompted the United States government to implement the Federal Radio Commission in 1926 and the Radio Act of 1927. With tighter regulation the radio experience improved greatly.

Regulation helped develop the industry and with that maturation came the entry of big business. In the early days of radio, radio stations were considered a public service and not a means to generate a profit. Before long, shows began to offer advertising slots to help offset expenses. Radio shows would be “brought to you by” a company who often had editorial control or influence over the show’s content, often with a short commercial before, after, or during an intermission. Popular corporate sponsored shows included The Eveready Hour and The Voice of Firestone.

The impact of radio on our culture

In the late 1920’s, using radio technology, a visible image was broadcast over the airwaves. This would go on to mature into the widely available “television” broadcast technology. In the decade following, FM radio was introduced to the market which offered much clearer broadcasts relatively free of static and noise. The first experimental FM radio station, WIXOJ, began broadcasting in 1937 with many new FM stations quickly following.

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Types of radios

In the beginning, crystal radios were the first to be manufactured. Crystal radios used a piece of lead galena crystal and a cat whisker to tune the radio signal. They required no power other than the power received from the radio waves themselves. Advertisements for crystal radio kits appeared in boys magazines and sold for about $6 dollars. Crystal radios were easy for people to make at home although the sound had to be listened to through an earphone and was weak and full of static.

Technically speaking, a crystal radio works like this:

1920 Crystal Radio setAn antenna is used to pick up the radio waves and convert them to electric currents. A tuned circuit selects the signal of the radio station to be received, out of all the signals received by the antenna. This circuit consists of a coil of wire called an inductor or tuning coil and a capacitor connected together, one or both of which is adjustable and can be used to tune in different stations. In some circuits a capacitor is not used, because the antenna also serves as the capacitor. The tuned circuit has a natural resonant frequency, and allows radio signals at this frequency to pass while rejecting signals at all other frequencies.

1925 Crystal Radio setA semiconductor crystal detector extracts the audio signal (modulation) from the radio frequency carrier wave. It does this by only allowing current to pass through it in one direction, blocking half of the oscillations of the radio wave. This rectifies the alternating current radio wave to a pulsing direct current, whose strength varies with the audio signal. This current can be converted to sound by the earphone. Early sets used a cat’s whisker detector, a fine wire touching the surface of a pebble of crystalline mineral such as galena. It was this component that gave crystal sets their name. An earphone is used to convert the audio signal to sound waves so they can be heard. The low power produced by crystal radios is insufficient to power a loudspeaker so earphones are used.

In 1924, vacuum tubes were introduced to the market and replaced crystals. Vacuum tubes allowed the signal to be picked up over greater distances and with more clarity. Vacuum tubes produced sound of a quality that exceeded that of popular phonographs. Strangely, the introduction of vacuum tubes impacted the style of music that was popular too. High, powerful voices such as opera singers, had a tendency to blow out the tubes in the radio. As a result, a gentle style, called “crooning”, developed and became a popular style of singing during the 1930’s.

The Invention of radio

Family listening to radio in living roomThe road to the radio craze of the 1920’s was a long, complicated, and controversial trek. Even the determination of who invented the radio is practically impossible and widely argued with many taking credit for radio’s invention. In reality, it was a progression of innovations, each built upon the innovation prior to it, that birthed radio technology.

Early 1920's Amateur radio stationIn the early 1800’s, the relationship between electric current and magnetism became known. During the century, several scientists stumbled across wireless communications in their experiments but did not pursue the idea or misinterpreted the reason these wireless communication phenomena occurred. For instance, static generated wirelessly and audible in a nearby telephone receiver was recognized (and documented) but useful applications of the mysterious occurrences were not necessarily considered. Still, several scientists during the era conducted experiments to prove the relationship between electric current and magnetism and built upon radio theory, bit by bit, over the course of the century. These intermittent steps (and stumbles) were all made possible by the discoveries of James Clerk Maxwell. It was Maxwell who developed Maxwell’s Equations, which described electromagnetic waves, and laid the groundwork for the discovery of wireless communications.

In 1831, Michael Faraday discovered electromagnetic induction (the production of a voltage across a conductor moving through a magnetic field). Faraday proposed that electromagnetic forces extended into the empty space around a conductor. Not recognizing the significance of his discovery (the ability to generate radio waves), Faraday did not complete any further work in this area.

Decades later, in 1884, Temistocle Calzecchi-Onesti of Fermo, Italy, invented a rudimentary device that could respond to radio waves transmitted through the air. He called the device, which is considered the first practical radio detector, a “coherer”. The principles of the coherer device were later improved upon by Oliver Lodge, Edouard Branly, and Guglielmo Marconi and was influential in the development of radio.

NBC Radio CityFour years later, between 1886 and 1888, Heinrich Rudolf Hertz demonstrated the transmission and reception of electromagnetic waves that had been predicted by Maxwell’s equations decades earlier. Hertz was the first person to intentionally transmit and receive radio signals. Like those before him, Hertz saw no practical use for his discovery.

In 1891, Nikola Tesla became interested in radio technology. In 1893, he developed the means to produce radio frequency currents and demonstrated the principles of radio transmissions at St. Louis, Missouri. Addressing the Franklin Institute of Philadelphia and the national Electric Light Association, he described in detail the principles of radio communication. Tesla’s device contained all the elements that were incorporated into later commercial radio systems (before the introduction of vacuum tubes). Tesla’s advances in the radio field led other scientists to investigate wireless methods and improve upon Tesla’s discoveries.

On August 14, 1894, at a meeting of the British Association for the Advancement of Science at Oxford University, Oliver Lodge gave a lecture on the work of Hertz (recently deceased) and transmitted radio signals, in the form or Morse code, to demonstrate their potential for communication. This was one year before Marconi but one year after Tesla did the same thing (by this time, it was obvious that the scientific community was greatly interested in wireless communications). Lodge improved on the coherer radio receiver while using Tesla coils for the transmitter. In August of 1898, U.S. Patent 609,154 was issued for “Electric Telegraphy”. In 1912, Lodge sold the patent to Guglielmo Marconi.

Marconi and his Spark Gap Radio TransmitterGuglielmo Marconi conducted transatlantic radio communication experiments in 1901 and established the first commercial transatlantic radio service in 1907. Five years later Marconi purchased Lodge’s patent for “Electric Telegraphy”. In an odd twist, the U.S. Patent Office reversed its patent decision and awarded the patent for the invention of the radio to Marconi, stating the previous patent held by Tesla was invalid on the basis of prior art. It is now believed that the decision to reverse the patent was influenced by Marconi’s financial backers which included influential scientist and businessmen such as Thomas Edison and Andrew Carnegie. The nullification of the patent allowed the United States to avoid having to pay royalties that were being claimed by Tesla for his patents (particularly with regard to the royalties owed from the use of World War I radio transmitters).

Reginald Fessenden radio stationOn December 24, 1906, Reginald Fessenden used an Alexanderson alternator and rotary spark-gap transmitter to make the first AM (Amplitude-Modulated) radio broadcast. AM radio differed from the typical spark-gap radio in one very important way. Spark-gap radio covered the entire spectrum of bandwidth and was intended to transmit to a single receiver. AM radio on the other hand, allowed the transmitter to send signals to more than one station. Fessenden’s broadcast, which was transmitted on Christmas Eve, was heard by ships at sea and consisted of Fessenden play O’ Holy Night on his violin and reading a passage from the Bible.

In April of 1909, Charles David Herrold, an electronics instructor in San Jose, California built the world’s first broadcast station. Calling the station “San Jose Calling”, Herrold broadcast both voice and music. He began broadcasting music and entertainment on a regular basis between 1912 and 1917 to fellow radio enthusiasts, using the callsigns FN and SJN. He had the world’s first regularly scheduled broadcasts, allowing listeners to tune in at a known time. He coined the terms “narrowcasting”, for transmissions to a single receiver such as ships, and “broadcasting”, for transmissions destined to a wide audience. Herrold designed omnidirectional antennas which he mounted on several buildings throughout the San Jose area. Herrold’s “San Jose Calling” station went on to become KCBS in San Francisco. Charles Herrold did not profit from his pioneering work and and later became a janitor at a local shipyard.

Charles Herrold Radio Station - the world's first broadcast stationInventor Edwin Howard Armstrong is often credited with developing many of the features of radio that we know today. Armstrong patented three important inventions that made radios much easier to operate. Armstrong patented “regeneration, or the use of positive feedback to increase the amplitude of received signals to the point where they could be heard without the use of headphones. Armstrong also invented the super heterodyne circuit which allowed radio manufacturers to do away with the many tuning controls that were required to tune in to a station and at the same time, made radios much more sensitive. Armstrong’s third great contribution was FM which gave listeners static free broadcasts with better sound quality and fidelity than was possible with AM radio.

If the path to the invention of the radio seems like it snaked and wound through the contributions of many people, it did. Other scientists and inventors that contributed to the invention and improvement of wireless technology and telephony include:

Georg von Arco: European pioneer.

Edouard Branly: invention of the Branly coherer around 1890.

Temistocle Calzecchi-Onesti: constructed a tuning “tube”.

Archie Frederick Collins: Arc transmitter for voice broadcasts, 1899.

Amos Dolbear: Earth transmission, U.S. Patent 350,299.

Thomas Alva Edison: “Etheric Force” experiments 1875; U.S. Patent 465,971, 1891.

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Michael Faraday: discovered electromagnetic induction.

Reginald Fessenden: advanced “continuous” wave transmission.

Benjamin Franklin: First to experiment with an elevated conductor.

Hans Christian Ørsted: discovered that a magnetic field surrounds a wire carrying current.

Joseph Henry: transmitted radiant energy from a capacitor through a coil and detected it 100 feet (30 m) away, December 1840.

Charles Herrold: advanced radio broadcasting.

David E. Hughes: early experiments with transmission and reception.

Mahlon Loomis: first to use the combination of an aerial wire and ground connection.

Guglielmo Marconi: First to achieve successful radio transmission.


Jozef Murgaš: extensive work in the late 1890s.

G. W. Pierce: circuits for crystal oscillators for fixed-frequency operation.

William Henry Preece: early experiments in electromagnetism and wireless telephony.

Augusto Righi: continued Hertz’s experiments.

Harry Shoemaker: 1901 to 1905; 40 patents.

Adolphus Slaby: European pioneer.

John Stone Stone: 1901 to 1904; 70 patents.

Nathan Stubblefield: wireless telephony demonstrations around 1902; U.S. Patent 887,357, 1908.

Nikola Tesla: 1891 to 1914; 27+ patents related to the transmission of electrical energy without wires.

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