The glorious development history of the Radio
2008-08-20

                                                                                  The glorious development history of the Radio       The radio is a device which receives electromagnetic waves from the air that are sent by a radio transmitter. Electromagnetic waves are a combination of electrical and magnetic fields that overlap. The radio converts these electromagnetic waves, called a signal, into sounds that humans can hear.       Radio owes its development to two other inventions, the telegraph and the telephone; all three technologies are closely related. Radio technology began as "wireless telegraphy". The Roots of Radio    

   During the 1860s, Scottish physicist, James Clerk Maxwell predicted the existence of radio waves; and in 1886, German physicist, Heinrich Rudolph Hertz demonstrated that rapid variations of electric current could be projected into space in the form of radio waves similar to those of light and heat.       In 1866, Mahlon Loomis, an American dentist, successfully demonstrated "wireless telegraphy." Loomis was able to make a meter connected to one kite cause another one to move, marking the first known instance of wireless aerial communication.

The development of Radio       Guglielmo Marconi successfully sent the first radio message across the Atlantic Ocean in December 1901 from England to Newfoundland. Marconi's radio did not receive voice or music. Rather, it received buzzing sounds created by a spark gap transmitter sending a signal using Morse code. 

      The radio got its voice on Christmas Eve 1906. As dozens of ship and amateur radio operators listened for the evening's traffic messages, they were amazed to hear a man's voice calling "CQ, CQ" (which means calling all stations, I have messages) instead of the customary ditsy and dash of Morse code. The message was transmitted by Professor Reginald Aubrey Fessenden from a small radio station in Brant Rock, Massachusetts. 

      In the years from 1904 to 1914, the radio went through many refinements with the invention of the diode and triode vacuum tubes. These devices enabled better transmission and reception of voice and music. Also during this time period, the radio became standard equipment on ships crossing the oceans.       The radio came of age during World War I. Military leaders recognized its value for communicating with the infantry and ships at sea. During the WWI, much advancement was made to the radio making it more powerful and compact. In 1923, Edwin Armstrong invented the super heterodyne radio. It was a major advancement in how a radio worked. The basic principles used in the super heterodyne radio are still in use today. 

      On November 2, 1920 the first commercial radio station went on the air in Pittsburgh, Pennsylvania. It was an instant success, and began the radio revolution called the "Golden Age of Radio." The Golden Age of Radio lasted from the early 1920s through the late 1940s when television brought in a whole new era. During this Golden Age, the radio evolved from a simple device in a bulky box to a complex piece of equipment housed in beautiful wooden cabinets. People would gather around the radio and listen to the latest news and radio plays. The radio occupied a similar position as today's television set.       On June 30, 1948 the transistor was successfully demonstrated at Bell Laboratories. The transistor allowed radios to become compact, with the smallest ones able to fit in a shirt pocket. In 1959, Jack Kilby and Robert Noyce received the first patent for the integrated circuit. The space program of the 1960s would bring more advances to the integrated circuit. Now, a radio could fit in the frame of eyeglasses or inside a pair of small stereo earphones. Today, the frequency dial printed on the cabinet has been replaced with light emitting diodes or liquid crystal displays. 

      For almost a century, radio communication has played a vital role in the society. Such diverse applications as television, mobile phones, aircraft navigation and two-way radio all depend on the ability to convey information ‘through the ether’ in the form of electromagnetic waves, and require access to appropriate radio spectrum.       But now, with the popular of the digital signals, Radios are being combined with computers to connect the computer to the Internet via satellites. Eventually radios will convert from analog to digital broadcasting. Analog signals are subject to fade and interference, digital signals are not. They can produce high quality sound like that found on a CD.       Digital radios can be programmed for specific stations, types of music, news, etc. Eventually, radios will have mini-computers built in to process sounds in numerical patterns "digits" rather than an analog waveform. This will allow listeners to program their radios for favorite radio stations, music type, stock quotes, traffic information, and much more.