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Before
television invaded our homes, it was the radio that held sway. From
roadside tea stalls to the insides of posh bungalows, it was the
sound of the radio broadcast that filled the air.
As with
several other things, the invention of the radio too cannot be
attributed to a single person. It was a culmination of the efforts
of Scottish physicist James Clerk Maxwell, in 1864. He was the first
to develop the theory of electromagnetic waves, which was given
practical confirmation in the laboratory in 1888 by German physicist
Heinrich Hertz; later, it was put to practical use by Italian
inventor Guglielmo Marconi. |
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Guglielmo Marconi
As it happened, while on a vacation in the
mountains in the summer of 1894, the young Marconi picked up a
technical magazine and read Hertz’ story about electrical waves. It
triggered off in him an idea. What if the electrical waves were more
powerful and better controlled? Would it then be possible to use
them to send signals across space for a considerable distance?
Marconi became immensely excited and cutting short his vacation, he
rushed home to begin assembling the kinds of equipment Hertz had
used to produce electrical waves.
Prior to
Marconi’s experiments, a Russian scientist, Alexander Popov, had
been trying to find ways to detect thunderstorms in advance. What he
desired to know was whether it was possible to detect the storm's
electrical energy when it was far away? When he found a positive
answer to his question, he had effectively invented a radio
receiver. Thereafter, he proceeded to put together the world’s first
system for sending and receiving wireless electronic communications.
Popov sent and received a “wireless” signal across 600 yards, in
early 1895. Marconi, who remained ignorant of Popov’s achievement,
soon achieved the same kinds of results and the radio was born.
Marconi walked away with the credit because Popov’s work had been
restricted to the Russian military and considering that it was a
revolutionary process, the Russians were apparently unwilling to
share the invention with the rest of the world.
The
frequency of a radio station is determined by the number of times it
sends out a wave of energy per second. Each of these cycles of
energy is called Hertz, after the German physicist Heinrich Hertz
who was the first person to tame these sparks and turn them into
controlled “waves” of electrical energy that traveled invisibly
through the air.
What happens in a radio
reception? A receiving aerial picks up minute voltages in response
to the waves sent out by a transmitter. A tuned circuit selects a
particular frequency, usually by means of a variable capacitor
connected across a coil of wire. A demodulator then disentangles the
audio signal from the carrier. An amplifier boosts the audio signal
for feeding to the loudspeaker. In a superheterodyne receiver, the
incoming signal is mixed with an internally generated signal of
fixed frequency, so that the amplifier circuits can operate near
their optimum frequency.
In the year 1916, founder of
the Marconi company, David Sarnoff, suggested the development of
what he called the “Radio Music Box System.” He recommended putting
the equipment in an attractive box that people could buy, in the
place of the complicated radio receiving apparatus then is use.
Sarnoff predicted his idea would generate sales worth 75 million
dollars within three years. When World War I ended, the Radio
Corporation of America was founded, and in its first three years of
selling Radio Music Boxes, it sold 83 million dollars worth radio
boxes and Sarnoff went on to become the head of the corporation. |
