Radio Waves :: essays research papers

Radio Waves In the modern society, radio is the most widely used medium of broadcasting and electronic communication : it plays a major role in many areas such as public safety, industrial manufacturing, processing, agriculture, transportation, entertainment, national defense, space travel, overseas communication, news reporting and weather forecasting. In radio broadcasts, they use the radio waves which can be both microwaves and longer radio waves. These are transmitted in two ways: amplitude modulation (AM ) and frequency modulation ( FM ). These two kinds of wave have many differences. Radio waves are among the many types of electromagnetic waves that travel within the electromagnetic spectrum. Radio waves can be defined by their frequency (in hertz, after Heinich Hertz , who first produced radio waves electronically), which is number of times they pass through a complete cycle per second; or by their wavelength, which is determined by the distance (by meters) that is traveled from the crest of one wave to the crest of the next. Radio frequencies are measured in units called kilohertz, megahertz, and gigahertz. (1 kilohertz = 1000 hertz : 1 megahertz = 106 hertz, 1 gigahertz = 109 hertz). All radio waves fall within a frequency range of 3 kilohertz, or 3000 cycles per second to 30 gigahertz. Within the range of frequencies, radio waves are further divided into two groups or bands such as very low frequency ( VLF 10-30 kHz ), low frequency (LF 30-300 KHz), medium frequency ( MF 300-3000 KHz), high frequency ( HF 3-30 MHZ) and very high frequency ( VHF 30-300MHZ). Amplitude modulation is the oldest method of transmitting voice and music through the airwaves is by amplitude modulation. This is accomplished by combining a sound wave from a microphone, tape, record, or CD with a "carrier" radio wave. The result : a wave that transmits voice or programming as its amplitude ( intensity ) increases and decreases. Amplitude modulation is used by station broadcasting in the AM band and by most international short wave stations. Frequency modulation is another way to convey information, voice , and music on a radio wave is to slightly change, or modulate, the frequency. The main advantage of FM broadcasting is of it is static free. But the drawback to FM is since the frequency is varied, station takes up more room on the band. Frequency modulation is, of course, used on the FM band. And it is used for "action band" and ham transmission in the VHF/UHF frequency range. In amplitude modulation, what is modified is the amplitude of a carrier wave on one specific frequency.