Radio waves works by sending invisible waves over million of miles , it transmits data, conversation, music and much more through signals that are detectable on certain frequencies .
The radio uses continuous sine waves because there are different devices that use radio waves at the same time, “a sine wave is a type of continuously varying wave that radiates out from the antenna and fluctuates evenly through space” (Cell phone radiation.2001.[online].How stuff work[Accessed 10/01/2012])
However each different radio signals uses different sine wave frequencies and that is how the are separated from each other, into different bands.
The radio has two parts to it that make it work, the transmitter takes the data which could be music or someone's voice and encodes it into sine waves and then transmits it into radio waves. The receiver than takes the sine wave and decodes the sine wave back into the data or music that was sent so we can hear it as the message instead of static, but it must be on the right frequency wave to hear it correctly. The transmitter and the receiver both use antennas to give out and take in signal.
There are lots of other technologies that use radio waves, such as mobile phones, Bluetooth, wireless connection, the kindle, televisions and much more.
Radio waves can travel from a transmitting aerial in one of three ways: surface or ground wave by following the curvature of the earths surface, sky wave it travels skywards but if its below a certain frequency around 30hz it is sent back to the earth after being reflected by the ionosphere and the last way is space wave this is only possible if it is a V.H.F- very high frequency or U.H.F- ultra high frequency or a microwave, this is useful for satellite communication.
The common radio frequency bands are: AM radio, Short wave radio, Television stations and FM radio.
Some radio stations can travel much farther than 40 miles due to the ionosphere, electrically charging the waves because of this s hort-wave can circle the globe, also AM stations transmit hundreds of miles at night.
The ionosphere allows certain frequencies of radio waves to bounce of it, which makes the waves bounce between the ground and the ionosphere, thus making their way around the planet. The composition of the ionosphere is different at night and during the day because there is no sun at night, you can listen to some radio stations better because the reflection characteristics of the ionosphere are enhanced at night.
An aerial is used to radiate or pick up radio waves, one of the commonly used aerial is the dipole aerial. It is made up of two vertical or horizontal piece of metal that conduct or wires. This are used in radio.
Another aerial is parabolic dish aerial, which is in the shape of a large metal saucer. The waves fall onto the dish from a small dipole, which is fed through the transmitter, the radiation patterns from these aerials is directional making them suitable for line of sight communication
Transmitting aerials handle many kilowatts of radio frequency. Receiving aerials deal with milliwatts due to the voltage and currents induced by passing radio waves.
Dipoles aerials are used to receive television and very high frequency radio signals. If they are pointed in the direction if the transmitter and aligned to polarisation of the signal they can reach maximum power.
Electrical signals that represent information from computer, microphone or a video camera can be transmitted from one places to many other places via radio waves or cables of copper. Audio signals are generally transmitted using a cable, but many of them require a carrier wave. The carrier wave allows the information to transmitted through the space as an electromagnetic wave used in radio communication. In the modulator, signal from the information source are added to the carrier, then the modulated signal is then sent along a channel in the propagating medium which is either a cable or radio waves by a transmitter. The receiver may have to choose and amplify the modulated signal before it is demodulated and the information is extracted for the receptor of the information.
In an FM transmission, after the sound wave frequency is the transmitted (via a microphone) into electromagnetic oscillations the frequency of the sound waves can be "added" or "subtracted" in a set proportion from the set FM transmission frequency. The amplitude of the FM waves is determined by the amplitude of the sound waves. Physicsforums.2004.[Online].Transmission-Fm/Am. Available from the worldwide web: < http://www.physicsforums.com/showthread.php?t=13626 >
In an AM transmission the reverse happens. The amplitude of the AM waves is determined by the frequency of the sound waves and the frequency of the AM waves is determined by them amplitude of the sound waves - with some proportionate addition/subtraction from the set AM transmission frequency. Physicsforums.2004.[Online].Transmission-Fm/Am. Available from the worldwide web: < http://www.physicsforums.com/showthread.php?t=13626 >
Phones work by sending signals down a wire, the microphone changes sound waves into electrical signals and the speaker changes signals into sound waves.
Mobile telephones uses cells, cells are radio frequency that are used in the locally area, each one has its own frequency and the cells adjacent to it has different frequencies and they each either contain a base station transmitter or receiver.
A phone is radio transmitter or receiver, the networks connects to the public switched telephone network. Your phone’s location is in the network’s database at all times.
Television signals are transmitted by using a transmitter which send the information to a receiving aerial and tuner by radio waves. It is uses Ultra high frequency (470-582MHz).
The first ever regular television service was open in 1936 by the BBC, but was suspended in 1939 due to world war two. It was opened up in Alexandra palace and it used 405 lines for each television picture, which is standard definition line standards, it used to be a high definition and was used in the first ever all electronic high definition television service by the BBC. Pembers.20010.[Online].World TV standards. Available from the worldwide web: http://www.pembers.freeserve.co.uk/World-TV-Standards/Line-Standards.html#Line-Standards >
To receive a signal it needs to be captured by a satellite dish, a satellite dish is an antenna but its designed to focus on a specific broadcast source, the information is sent to the dish via a satellite dish using radio waves and is received through the feed horn. The beam hits the curved dish and it reflects the signal in to the feed horn. A new design of the satellite dish has two or more feed horns so that the dish can pick up signals from more than one satellite and it different signal is reflected in to a separate feed horn.
Figure 2. how stuff works.[online] satellite-TV[Accessed 10/01/2012]: < http://electronics.howstuffworks.com/satellite-tv6.htm >
Figure 1 Radio waves are invisible waves that carry data, music, sound or pictures. Microwaves can be used to transmit signals for mobile phone calls. Microwave transmitters and receivers on buildings communicate with mobile phones that are in range. Infrared is used for military use such as surveillance, tracking and night vision and civilian use such as wireless communication, remote controls and radio forecasting. Ultraviolet is found in sunlight, like radio waves it is invisible and skin reacts to it by turning darker. to much exposure to this can cause cancer. Visible light is light that the human eye can see, it is responsible for the human sight. A primary source is the sun. X-ray is used for observing the internal structure of objects medical use and also used in the airport Gamma ray can be use for sterilising food and medical equipment, also detection and treatment of cancer.
The uses of radio waves are vast, it can be used to send data, music, pictures and much more. It is used in radios to transmit sound from the radio station to cars, houses and phones the sound is carried by the waves to the receiver and the tuner picks out the sound and it is then demodulated into it original form. It is also used to send signal to satellite dishes from orbiting satellites which is captures by the feeding horn and that’s how we are able to get certain channels. They are also used for mobiles sending signals down a wire, the microphone changes sound waves into electrical signals and the speaker changes signals into sound waves.
Without the use of radio waves technology wouldn’t of been able to progress in the direction it, we would have had advance technology when it came to phones, radios, television and many others. Also without this technology we might not of been able to win world war two because we would have been able to uncover the Germans codes and been able to communicate with our allies overseas. We would have been able to use phones without this technology, if it wasn’t discovered many other technologies won’t of existed (and worse of all I wouldn’t of made this presentation).
How stuff works.2001.[online] cell phone radiation [Accessed 10/01/2012].Available from the worldwide web: < http://electronics.howstuffworks.com/cell-phone-radiation1.htm >
Figure 1.electromagnetic spectrum.2012.[online] Wikipedia[Accessed 14/01/2012].Available from the worldwide web< http://en.wikipedia.org/wiki/File:EM_Spectrum_Properties_edit.svg >
Physicsforums.2004.[Online].Transmission-Fm/Am. [Accessed 10/01/2012].Available from the worldwide web: < http://www.physicsforums.com/showthread.php?t=13626 >
Pembers.20010.[Online].World TV standards. Available from the worldwide web: http://www.pembers.freeserve.co.uk/World-TV-Standards/Line-Standards.html#Line-Standards >
Figure 2. how stuff works.[online] satellite-TV[Accessed 10/01/2012] Available from the worldwide web: http://electronics.howstuffworks.com/satellite-tv6.htm
How stuff works.2001.[online].AM Radio.[accessed [19/01/2012].Available from the worldwide web: < http://www.howstuffworks.com/radio8.htm >
How stuff works.2001.[online] .Am radio diagram. [Accessed 10/01/2012] Available from the worldwide web : http://www.howstuffworks.com/radio8.htm
How cell phones work .2006.[online].How mobile networks work diagram . [Accessed 13/01/2012] . Available from the worldwide web: < http://soni2006.hubpages.com/hub/benefits-of-mobile-phones-how-cell-phones-work-where-to-buy-them >