IntroductionThis presentation will take you through the uses ofAM radio waves outside of radio broadcasting. Thisslide show will take you through:What is a radio wave, and the electromagneticspectrumHow these waves are used outside the radioSome good and bad points about using thesewaves.
The spectrumThe electromagnetic spectrum is a graph, if you will, of allthe waves known to man. This presentation will befocusing on the radio waves. Which cover a large part ofthe spectrum, the reason for this is radio waves can rangefrom being 1 millimetre to around 100 kilometres in sizeRadio waves can be both man made and natural. Naturalwaves are made by astronomical objects and lightening;hence the reason why when lightening strikes you canhear interference in your radio.To the right is an example of astronomicalradio waves.
This is Nasas’ version of the Spectrum. So as you can to your leftwe have the large ranging radio waves, and to the right we haveour microscopic gamma waves. The pictures underneath thespectrum are to give a little size reference so as you can see radiowaves can be the size of a football pitch and gamma rays the sizeof a nuclei!Also on this spectrum is visible light for humans, which are foundbetween infrared and ultra violet rays, so although radio wavescan be the size of a football pitch there is no possible way thatthe human eye can see them!
How important are these invisiblewaves?As we know AM and FM radio waves are used mainly forcommunication, radio to be precise. However they arealso used a lot in things such as:Radar and other navigation systems (GPS, Satnav etc.)Satellite communicationsComputer networksTVMobile phones
TVWhen we think of TV we instantly think of broadcast TV, where all of our favouriteshows are played. The importance of radio waves is that broadcast TV wascompletely based upon the all ready existence of broadcasting radio systems inthe 1920’s. And it is high powered radio transmitters the broadcast TV signals toindividual TV receivers.UHF, or ultra high frequency, is the radio frequency that TV uses to transmit;interestingly enough this is also the same wavelengths that the police and militaryuse for their radios.Radio waves are still used for TV broadcasting but it was most notable when TV’shad antennas on top of them, and when cable companies set a little satellite dishoutside your house.
Mobile phonesMobile phones work because of radio waves; whensomeone calls you their voice is transmitted, via radio wave,to a base station and then is connected to the fixed andmobile phone network.These base stations are basically radio antennas, for yourmobile. Each base station can cover a set distance and eachdistance is called a cell, so as you move around the countryyou are moving cells. This is also the reason why they arecalled cell phones.To the right is an map example of cells
Continued………As we know AM radio waves travel much furtherthan FM waves and are used for communications,this is why base stations use AM radio waves, sothey can cover more ground with less base stations.Also this does mean that (especially in olderphones) the further away you get from a basestation, go into a tunnel or even get stuck in alightening storm your phone signal can becomeweak, pick up interference or in the case of a tunnelyou can lose signal altogether.
Medical uses and dangersFor many years there has been an argument about radio waves used inmobile phones, there are arguments for and against signs that mobiles cangive off harmful radiation to users. This is because when using your phonethe noise you make is encoded onto a continuous sine wave. It is this waveand the fact that the electromagnetic radiation given off by mobile phones isin direct contact with head tissue.However it’s not all doom and gloom with radio waves as they are used inmedicines for things such as in magnetic resonance imaging (MRI scans)Also there have been cases of pre-cancerous cells and indeed cancerous cellsbeing killed via the use of radio waves radiation without side effects orharming other cells around the cancer. AKA Radiotherapy.
SummeryThis power point has taken you through:The basics of what the electromagnetic spectrum is and where AM radiowaves fits inThe importance of these wavesAnd the uses of these waves outside of radio (including TV, Mobile, dangersand medicine)
Thank you very much for listening, any questions?
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