Radio Waves

Radio waves are an invisible form of electromagnetic radiation that varies in wavelength from around a millimeter to 100,000 km, making it one of the widest ranges in the electromagnetic spectrum. "Radio" is a catch-all term describing all forms of electromagnetic radiation with a wavelength longer than a millimeter and a frequency above 300 GHz. Frequency refers to how long the measured time is between the "crest" and "trough" of a wave arriving at the source. For visible light, the frequency is in the 450-750 terahertz range, meaning in a single second of waves, 450-750 crests and troughs pass through a detector. Discovery and Utilization:        Radio waves were first predicted by mathematical work done in 1865 by James Clerk Maxwell. Maxwell noticed wavelike properties of light and similarities in electrical and magnetic observations. He then proposed equations that described light waves and radio waves as waves of electromagnetism that travel in space. In 1887, Heinrich Hertz demonstrated the reality of Maxwell's electromagnetic waves by experimentally generating radio waves in his laboratory.[1] Many inventions followed, making practical the use of radio waves to transfer information through space. 5 different types of radio waves and there uses: There are more than 5 Radio portion of the electromagnetic spectrum Radio waves are divided up into bands by frequency (and corresponding wavelength) as shown in the radio frequency spectrum table below. Extremely low frequency ELF 1 3–30 Hz 100,000 km – 10,000 km Communication with submarines Super low frequency SLF 2 30–300 Hz 10,000 km – 1000 km Communication with submarines Ultra low frequency ULF 3 300–3000 Hz 1000 km – 100 km Communication within mines Very low frequency VLF 4 3–30 kHz 100 km – 10 km Submarine communication, avalanche beacons, wireless heart rate monitors, geophysics Low frequency LF 5 30–300 kHz 10 km – 1 km Navigation, time signals, AM longwave broadcasting Medium frequency MF 6 300–3000 kHz 1 km – 100 m AM (Medium-wave) broadcasts High frequency HF 7 3–30 MHz 100 m – 10 m Shortwave broadcasts, amateur radio and over-the-horizon aviation communications Very high frequency VHF 8 30–300 MHz 10 m – 1 m FM, television broadcasts and line-of-sight ground-to-aircraft and aircraft-to-aircraft communications Ultra high frequency UHF 9 300–3000 MHz 1 m – 100 mm television broadcasts, microwave ovens, mobile phones, wireless LAN, Bluetooth, GPS and Two-Way Radios such as FRS and GMRS Radios Super high frequency SHF 10 3–30 GHz 100 mm – 10 mm microwave devices, wireless LAN, most modern Radars Extremely high frequency EHF 11 30–300 GHz 10 mm – 1 mm Radio astronomy, high-speed microwave radio relay. Source: wiki