Electromagnetic radiation is transmitted in waves or particles at different wavelengths and frequencies. This broad range of wavelengths is known as the electromagnetic spectrum EM spectrum). The spectrum is generally divided into seven regions in order of decreasing wavelength and increasing energy and frequency. The common designations are radio waves, microwaves, infrared (IR), visible light, ultraviolet (UV), X-rays and gamma-rays. Microwaves fall in the range of the EM spectrum between radio and infrared light.
What are Radio Waves?
Radio waves are a type of electromagnetic radiation with the longest wavelengths in the electromagnetic spectrum. They have have frequencies from 300 GHz to as low as 3 kHz, and corresponding wavelengths from 1 millimeter to 100 kilometers. Like all other electromagnetic waves, radio waves travel at the speed of light. Naturally occurring radio waves are made by lightning or by astronomical objects. Artificially generated radio waves are used for fixed and mobile radio communication, broadcasting, radar and other navigation systems, communications satellites, computer networks and innumerable other applications.
Different frequencies of radio waves have different propagation characteristics in the Earth’s atmosphere—long waves may cover a part of the Earth very consistently, shorter waves can reflect off the ionosphere and travel around the world, and much shorter wavelengths bend or reflect very little and travel on a line of sight.
What are Microwaves?
Microwave is a form of electromagnetic radiation with wavelengths ranging from about one meter to one millimeter corresponding to frequencies between 300 MHz and 300 GHz respectively. The prefix “micro-” in “microwave” is not meant to suggest a wavelength in the micrometer range. It indicates that microwaves are “small” compared to waves used in typical radio broadcasting in that they have shorter wavelengths.
Microwaves travel by line-of-sight; unlike lower frequency radio waves they do not diffract around hills, follow the earth’s surface as ground waves, or reflect from the ionosphere, so terrestrial microwave communication links are limited by the visual horizon to about 40 miles (64 km). At the high end of the band, they are absorbed by gases in the atmosphere, limiting practical communication distances to around a kilometer.
Microwave sources include artificial devices such as circuits, transmission towers, radar, masers, and microwave ovens, as well as natural sources such as the Sun and the Cosmic Microwave Background.
Microwaves can also be produced by atoms and molecules. They are, for example, a component of electromagnetic radiation generated by thermal agitation. The thermal motion of atoms and molecules in any object at a temperature above absolute zero causes them to emit and absorb radiation.
What are Infrared waves?
Infrared, sometimes called infrared light, is electromagnetic radiation with wavelengths longer than those of visible light. It is therefore invisible to the human eye. Most of the radiation emitted by a moderately heated surface is infrared; it forms a continuous spectrum. Molecular excitation also produces copious infrared radiation but in a discrete spectrum of lines or bands.
The infrared range is usually divided into three regions: near infrared (nearest the visible spectrum), with wavelengths 0.78 to about 2.5 micrometres (a micrometre, or micron, is 10-6metre); middle infrared, with wavelengths 2.5 to about 50 micrometres; and far infrared, with wavelengths 50 to 1,000 micrometres. Infrared light is emitted or absorbed by molecules when they change their rotational-vibrational movements. Infrared radiation is used in industrial, scientific, military, commercial, and medical applications.
Radio vs Microwave vs infrared waves
|BASIS OF COMPARISON||RADIO WAVE||MICROWAVE||INFRARED|
|Generation||A radio wave is generated when a charged particle is swiftly accelerated and decelerated in the air.||The microwaves are produced with the help of klystron or magnetron in which the radio wave is propagated in a magnetic field in order to generate microwave.||The primary source of infrared radiation is heat or thermal radiation. Any object which has a temperature radiates in the infrared.|
|Nature||Microwave is a high frequency and high energy wave.||The radio wave is a low frequency and low energy wave.||Infrared is a high frequency low energy wave.|
|Direction||These are omni-directional in nature.||These are unidirectional in nature.||These are unidirectional in nature.|
|At Low Frequency||At low frequency, they can penetrate through solid.||At frequency, they can penetrate through solid objects and walls, at high frequency they cannot penetrate.||They cannot penetrate through any solid object and walls.|
|Detection||The detection of a radio wave is done using aerials.||Microwave is detected using point contact diodes.||Infrared are detected using photon detectors|
|Frequency||Frequency ranges from 3 KHz to 1GHz.||Frequency ranges from 1GHz to 300 GHz.||Frequency ranges from 300GHz to 400 GHz.|
|Attenuation||Attenuation is high.||Attenuation is variable.||Attenuation is low.|
|Uses||Radio waves are commonly used in AM, FM, cellular systems etc.||Microwaves are commonly used in radar systems, aircraft navigation and microwave oven.||Infrared are commonly used in applications like remote sensing, remote controls, optical fibres, security systems and thermal imaging cameras which detect people in the dark.|
|Government License||Some frequencies in the radio-waves require government license to use.||Some frequencies in the microwave require government license others don’t.||Infrared wave frequencies do not require government license for use.|
|Propagation||Radio wave is usually propagated through sky mode.||Microwave uses the line of sight propagation.|
|Costs||Setup and usage costs are high.||Setup and usage costs are high.||Setup and usage costs are low.|
|Communication||Radio waves are use in long distance communication.||Microwave are used in long distance communication.||They are not used in long distance communication.|
|Security||Offers poor security.||Offers medium security.||Offers high security.|