FREQUENCY..
The number of times the polarity of an AC voltage changes per second determines its frequency. Frequency is measured in cycles per second or Hertz (Hz). 1.000 cycles per second is a kilohertz (kHz). 1.000.000 hertz is a Megahertz (MHz). The only difference between the 50 Hz electric power in your house and radio frequencies (RF) is the frequency, but 50 Hz electricity in a wire also produces electromagnetic radiation just like radio waves. Useful radio waves start at 30 kHz and go upward in frequency until you reach the infrared light waves. Light is the same kind of waves as RF except light is at a much higher frequency. Light waves are used like radio waves when they are confined inside fiber optic cable. Above the frequencies of light are found x-rays and gamma rays. The radio bands: the LW (Long Wave) band starts at 30 kHz and goes to 300 kHz. The MW (Medium Wave) band is from 300 kHz to 3 MHz. The HF (High Frequency) band is from 3 MHz to 30 MHz. The VHF (Very High Frequency) band is from 30 MHz to 300 MHz. The UHF (Ultra-High Frequency) band is from 300 MHz to 3 GHz. Above these frequencies are several microwave bands which are defined as the SHF (Super High Frequency) band.
The number of times the polarity of an AC voltage changes per second determines its frequency. Frequency is measured in cycles per second or Hertz (Hz). 1.000 cycles per second is a kilohertz (kHz). 1.000.000 hertz is a Megahertz (MHz). The only difference between the 50 Hz electric power in your house and radio frequencies (RF) is the frequency, but 50 Hz electricity in a wire also produces electromagnetic radiation just like radio waves. Useful radio waves start at 30 kHz and go upward in frequency until you reach the infrared light waves. Light is the same kind of waves as RF except light is at a much higher frequency. Light waves are used like radio waves when they are confined inside fiber optic cable. Above the frequencies of light are found x-rays and gamma rays. The radio bands: the LW (Long Wave) band starts at 30 kHz and goes to 300 kHz. The MW (Medium Wave) band is from 300 kHz to 3 MHz. The HF (High Frequency) band is from 3 MHz to 30 MHz. The VHF (Very High Frequency) band is from 30 MHz to 300 MHz. The UHF (Ultra-High Frequency) band is from 300 MHz to 3 GHz. Above these frequencies are several microwave bands which are defined as the SHF (Super High Frequency) band.
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