What is radio wave and how does it work?
Let’s first try to understand what is a wave. A wave is a propagating dynamic disturbance (change from equilibrium) of one or more quantities in physics, mathematics, and related subjects, commonly represented by a wave equation. At least two field quantities in the wave medium are involved in physical waves. Periodic waves occur when variables oscillate periodically around an equilibrium (resting) value at a specific frequency.
What are the different types of waves?
Mechanical and electromagnetic waves are the most widely studied forms of waves in classical physics. Stress and strain fields fluctuate about a mechanical equilibrium in a mechanical wave.
A mechanical wave is a local deformation (strain) in a physical medium that spreads from particle to particle by establishing local stresses that generate strain in surrounding particles. Sound waves, for example, are fluctuations in local pressure and particle motion that propagate through a medium. Seismic waves, gravity waves, surface waves, string vibrations (standing waves), and vortices are all examples of mechanical waves.
Coupling between the electric and magnetic fields in an electromagnetic wave (such as light) that maintains the propagation of a wave involving these fields according to Maxwell’s equations. Electromagnetic waves may pass through a vacuum and some dielectric material (at wavelengths where they are considered transparent). According to their frequencies (or wavelengths), electromagnetic waves are classified as radio waves, infrared radiation, terahertz waves, visible light, ultraviolet radiation, X-rays, and gamma rays.
What is radio wave?
As you can see that radio wave is a type of electromagnetic waves. Radio waves are a form of electromagnetic radiation with wavelengths greater than infrared light in the electromagnetic spectrum. The frequency of radio waves ranges from 300 gigahertz (GHz) to 30 hertz (Hz). The equivalent wavelength at 300 GHz is 1 mm (shorter than a grain of rice), while the comparable wavelength at 30 Hz is 10,000 km (longer than the radius of the Earth). Radio waves, like other electromagnetic waves, travel at the speed of light in a vacuum and at a somewhat slower speed in the Earth’s atmosphere. Charged particles undergoing acceleration, such as time-varying electric currents, produce radio waves.Lightning and celestial objects release naturally occurring radio waves, which are part of the blackbody radiation generated by all heated things.
James Clerk Maxwell, a Scottish mathematical scientist, predicted radio waves for the first time in 1867. Maxwell’s equations, his mathematical theory, predicted that a coupled electric and magnetic field might propagate over space as a “electromagnetic wave.” Maxwell argued that light was made up of electromagnetic waves with extremely small wavelengths. Heinrich Hertz, a German scientist, confirmed the actuality of Maxwell’s electromagnetic waves in 1887 by physically creating radio waves in his laboratory, demonstrating that they displayed the same wave qualities as light: standing waves, refraction, diffraction, and polarisation.Guglielmo Marconi, an Italian inventor, created the first operational radio transmitters and receivers during 1894–1895. For his radio work, he was awarded the Nobel Prize in Physics in 1909. Around 1900, commercial radio transmission began. Around 1912, the contemporary word “radio wave” supplanted the old word “Hertzian wave.”
Radio waves are used to transfer information across space in radio communication systems. At the transmitting end, the information to be conveyed is applied to a radio transmitter in the form of a time-varying electrical signal. The information, known as the modulation signal, can be an audio signal containing sound from a microphone, a video signal containing moving pictures from a video camera, or a digital signal containing data from a computer. An electrical oscillator in the transmitter produces an alternating current oscillating at a radio frequency, known as the carrier wave since it generates the radio waves that “transport” the information through the air.The information signal is used to modulate the carrier, changing some feature of it and “piggybacking” the information on it. The amplified modulated carrier is applied to an antenna. The oscillating current forces electrons back and forth in the antenna, generating oscillating electric and magnetic fields that radiate energy out from the antenna as radio waves. The information is transmitted to the receiver location through radio waves.
At the receiver, the incoming radio wave’s oscillating electric and magnetic fields drive the electrons in the receiving antenna back and forth, generating a small oscillating voltage that is a weaker reproduction of the current in the sending antenna. This voltage is delivered to the radio receiver, which receives the data transmission. The receiver first separates the targeted radio station’s radio signal from all other radio signals picked up by the antenna with a bandpass filter, then amplifies the signal to make it louder, and lastly extracts the information-bearing modulation signal in a demodulator.The recovered signal is routed to a loudspeaker or earphone to generate sound, or to a television display screen to generate a visual picture, or to other devices. A digital data signal is sent to a computer or microprocessor, which communicates with a human user.