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Why do radio waves with extremely long wavelengths such as ELF radio waves need huge antennas?
Wiki User
∙ 15y ago
Answer: An antenna is a tuned circuit, so it have to be tuned to the wavelength of the signal that it will transmit. If the antenna is not tuned properly some of the transmitted power will be feed back to the transmitter and will damage the output stage, SWR (Standing Wave Ratio) is very important, that is the ratio between the power that is transmitted by the antenna and the power that is fed back to the transmitter a zero is ideal but not always possible.
The lower the frequency the longer the wave length and a 1/4 wave length is the minimum length that will give one a good SWR. The formula to use when one design a antenna is 300/frequency in MHz, if the frequency is 30 MHz then it is 300/30 = 10 Meter divide it by 4 to get the length of the 1/4 wave antenna that is 2,5 meters.
Note: The antenna have to be multiples of a 1/4 wavelength like 1/2 wave or full wave, a 5/8 length can be used but it will need a L/C circuit at the input of the antenna to tune it to the frequency.
Wiki User
∙ 15y ago
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Are radio waves a form of sound or light?
When you listen to the radio, you are hearing sound, which has no resemblance to light, radio waves, or x-rays. However, the sounds you hear are created in the radio receiver, using information that was carried to your location by means of radio waves.
Radio signals are broadcast by what waves?
Radio waves are electromagnetic waves. Electromagnetic waves include waves such as X rays, ultraviolet light, visible light, infrared rays and so on, but you probably imagine radio waves to be quite different from these waves. Of the various kinds of electromagnetic waves, radio waves have a longer wave length than infrared rays, and are defined by the Radio Law as 'electromagnetic waves with a frequency of less than 3,000 GHz (3 THz)'Ultralow frequency radio wavesbelow 3kHzradio waves3kHz~3THz infrared rays3THz~380THz visible light380THz~790THz ultraviolet light790THz~105THz X rays105THz~107THz γ raysabove 107THzNames of radio waves Frequency Wave length Principal applications VLF(Very Low Frequency) 3kHz ~ 30kHz 100km ~ 10km LF(Low Frequency) 30kHz ~ 300kHz 10km ~ 1km Vessel / Airplane beacon MF(Medium Frequency) 300kHz ~ 3MHz 1km ~ 100m AM radio, Marine radio, Amateur radio HF(High Frequency) 3MHz ~ 30MHz 100m ~ 10m Shortwave broadcasting, Marine / Air radio, Amateur radio VHF(Very High Frequency) 30MHz ~ 300MHz 10m ~ 1m TV, FM, Fire radio, Police radio, Disaster PA radio network UHF(Ultra High Frequency) 300MHz ~ 3GHz 1m ~ 10cm Low power radio, Mobile-phone, Taxi radio, Amateur radio, TV, Wireless LAN SHF(Super High Frequency) 3GHz ~ 30GHz 10cm ~ 1cm Satellite broadcasting, Radar EHF(Extremely High Frequency) 30GHz ~ 300GHz 1cm ~ 1mm Satellite broadcasting, Radio astronomy, Radar submillimeter waves 300GHz ~ 3THz 1mm ~ 0.1mm
What are radiowaves and how they are formed?
Radio waves Radio waves are electromagnetic waves occurring on the radio frequency portion of theelectromagnetic spectrum.Discovery and utilizationRadio 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 Hertzdemonstrated the reality of Maxwell's electromagnetic waves by experimentally generating radio waves in his laboratory. Many inventions followed, making practical the use of radio waves to transfer information through space. Nikola Tesla and Guglielmo Marconi are credited with inventing systems to allow radio waves to be used for communication.For more information go to:http:/en.wikipedia.org/wiki/Radio_waves
What type of electromagnetic wave is the largest?
The section we call 'radio'. Of course, there's no end to the electromagnetic spectrum, at least not on the low-frequency end, so there's really no such thing as "greatest" wavelength. As frequencies go down past radio and below, wavelength just keeps getting longer ... the bit of radiation from the 60 Hz utility power lines has a wavelength of almost 5,000 kilometers ( ! ! ). But we don't use anything down there in the form of radiation ... antennas would need to be gigantic in order to be the least bit efficient ... so there's no popular name for the radiated form. The 'generic' answer to the question is: The type with the lowest frequency.
What is narrow bandwidth antenna?
An antenna (or aerial) is an electrical device which converts electric currents into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver. In transmission, a radio transmitter applies an oscillating radio frequency electric current to the antenna's terminals, and the antenna radiates the energy from the current as electromagnetic waves (radio waves). In reception, an antenna intercepts some of the power of an electromagnetic wave in order to produce a tiny voltage at its terminals, that is applied to a receiver to be amplified. An antenna can be used for both transmitting and receiving.Antennas are essential components of all equipment that uses radio. They are used in systems such as radio broadcasting, broadcast television, two-way radio, communications receivers, radar, cell phones, and satellite communications, as well as other devices such as garage door openers, wireless microphones, bluetooth enabled devices, wireless computer networks, baby monitors, and RFID tags on merchandise.Typically an antenna consists of an arrangement of metallic conductors ("elements"), electrically connected (often through a transmission line) to the receiver or transmitter. An oscillating current of electrons forced through the antenna by a transmitter will create an oscillating magnetic field around the antenna elements, while the charge of the electrons also creates an oscillating electric field along the elements. These time-varying fields radiate away from the antenna into space as a moving electromagnetic field wave. Conversely, during reception, the oscillating electric and magnetic fields of an incoming radio wave exert force on the electrons in the antenna elements, causing them to move back and forth, creating oscillating currents in the antenna.Antennas may also contain reflective or directive elements or surfaces not connected to the transmitter or receiver, such as parasitic elements, parabolic reflectors or horns, which serve to direct the radio waves into a beam or other desired radiation pattern. Antennas can be designed to transmit or receive radio waves in all directions equally (omnidirectional antennas), or transmit them in a beam in a particular direction, and receive from that one direction only (directional or high gain antennas).The first antennas were built in 1888 by German physicist Heinrich Hertz in his pioneering experiments to prove the existence of electromagnetic waves predicted by the theory of James Clerk Maxwell. Hertz placed dipole antennas at the focal point of parabolic reflectors for both transmitting and receiving.
What are the waves with the longest wavelengths in the electromagnetic?
ELF radio waves or extremely low frequency radio waves. These may have frequencies below 1 Hz in some cases!
Which waves in the electromagnetic spectrum have the longest wavelength?
The waves with the longest wavelengths are known as radio waves.
What kinds of waves have the longest wavelengths?
Radio waves have the longest wavelengths.
What kind of waves the longest wavelengths?
Radio waves have the longest wavelengths.
The electromagnetic waves with the longest wavelengths are?
Radio waves have the longest wavelengths in the electromagnetic spectrum
What are the longest wavelengths?
Radio waves.
What has the lowest frequency on the electromagnetic spectrum?
Extremely low frequency (ELF) radio waves. They can have wavelengths of over 60,000 miles (100,000 km) and frequencies from 3 to 300 Hz.
What wavelengths are longer than light but shorter than radio waves?
Infrared light, microwaves and radio waves have wavelengths longer than visible light. Radio waves have the longest wavelength.
What do you know about radio waves?
it is the longest wavelengths..
Which waves have shorter wavelengths radio waves or xrays?
X-rays have shorter wavelengths than radio, heat, infra-red, visible light, and ultra-violet.
Why do cell phones have very short antennas?
Cell phones use radio waves travelling at the speed of light with a typical frequency of 800 MHz, which is ten times greater than FM radio frequency. Due to shorter wavelengths, the cell phones use very short antennas.
Radio waves microwaves and ultraviolet rays have longer wavelenghts then visible light?
Gamma rays and radio waves are both electromagnetic waves. Radio frequency waves are a lower frequency, so they have a longer wave length.
