2. Radio waves and the electromagnetic
spectrum
Within the electromagnetic spectrum Radio waves have the lowest Frequency and longest
wavelength >1mm and can be far longer than a kilometre 1(St Andrews, n.d).
The radio band of the spectrum can be broken down further into the radio spectrum shown
below. This spectrum is split up to broadcast many devices such as: TV, Wi-Fi as well as the
traditional radio.
Figure 1
3. Advantages of UHF radio frequency
UHF is the useful to use as it is better at penetrating physical barriers such as buildings &
mountains than radio frequencies lower down in the radio spectrum.2
Because of its higher frequency UHF will cover a lower range but due to its wider frequency range
it allows more channels to be stacked together. 2
The shorter wavelength allows for antennas to be short compared to radio waves lower in the
electromagnetic spectrum. 2
‘To increase the limited range of UHF signals the waves can be reflected of charged particles in
the ionosphere than typical line of sight.’ (Wikipedia, 2012)3
4. Disadvantages of UHF
UHF equipment is usually more expensive than other frequency equipment.
A decreased line of sight compared with lower frequency radio waves which do not degrade as
much over long distances. 2
UHF frequencies are still prone to atmospheric conditions that effect VHF.
Figure2
5. Radio waves in Wi-fi
2 way communication from Wi-fi hub and wireless computer, meaning both devices act as
transmitters & receivers
Operating frequency of Wi-fi can either be 2.4GHz or 5GHZ within the UHF band (Brain and
Wilson, How stuff works)4
This is noticeably higher than TV & Radio, the increased frequency is used so more information
can be carried on the wave.
Like many other modern communication applications Wi-fi uses orthogonal frequency-division
multiplexing
Figure 3
6. Orthogonal Frequency division
multiplexing
Why is it used?
In devices that are wireless interference is a common problem, orthogonal frequency division
multiplexing reduces this issue by splitting the signal into multiple signals with different
frequencies. 5
Original signal Transmitting signal Received signal Final signal
Figure 4
Figure 1 demonstrates orthogonal frequency division multiplexing. The original signal is split into
various radio signals at different frequencies which are then mixed at the receiver to give a near
perfect signal at the receiver, had the signal not been split interference would have ruined the
signal.
7. Super high frequency band
The boundary where radio waves become microwaves and covers a frequency range of 3GHZ-
30GHZ.6
Have wavelengths of 10cm to 1cm.7
These waves are capable of projecting into space and consequently are used in satellite
broadcasting.
Because of their small wavelength they degrade over shorter distances but frequent radio relay
stations can solve this problem.
SHF are used mainly for point to point communications.
Figure 5
8. Mobile phones
Super high frequency waves are used in mobile phone technology for a number of reasons.
1. The wavelengths of SHF are small allowing mobile antennas to be small and therefore
increasing portability.
2. Compared to frequencies lower in the radio spectrum they have a much larger bandwidth
allowing multiple devices in the super high frequency channel; this allows enough bandwidth
for multiple mobile phones across the world.
The only drawback is that super high frequency waves degrade over short distances meaning a
higher expense for mobile companies to install signal towers.
Figure 6
9. Additional uses of radio waves
Emergency service radio – for example police radio.
Radar and GPS devices – satellite navigation, detecting fish shoals for trawlers or avoiding
underwater obstacles.
Medicine - MRI scans & Cancer treatment (removing tumours)8
Figure 7
10. The future of radio waves
Currently Nokia is researching possibilities of a phone that could absorb radio waves
to power phone batteries. If this is efficient enough future phones could have an infinite power
supply. 9
Though it is not certain some physicists believe twisting radio waves could gives us 100x the
bandwidth. Though other physicists oppose this belief there is still much research and
experimenting to be conducted. 10
11. The importance of radio waves –
summary.
The uses of radio waves go far beyond traditional radio
broadcasting and are used daily in modern lives. It can be said
they have increased communication and convenience.
It is likely that radio waves will be used in future communications
although we could see the decline in traditional AM/FM radio
broadcasting due to online radio.
12. Bibliography
1) Snow T.P. & Brownsberger K.R. (1997) Universe: Origins and Evolution
Ridpath I. (1997) Oxford Dictionary of Astronomyhttp://www.st-andrews.ac.uk/~bds2/ltsn/ljm/JAVA/SPECTRUM/details.html 12/1/2012
2) Radius gp 300, (n.d ) http://radiusgp300.reviewtrend.com/uhf-versus-vhf-which-two-way-radio-frequency-is-better 12/1/2012
3) Wikipedia (2012) , http://en.wikipedia.org/wiki/Ultra_high_frequency 17/1/2012
4) Brain, Marshall, and Tracy V. Wilson. "How WiFi Works" 30 April 2001. HowStuffWorks.com. <http://computer.howstuffworks.com/wireless-network.htm> 18
January 2012.
5) Charan Langton. “Orthogonal frequency division multiplexing tutorial” (2004)<complex to real(2004)http://www.complextoreal.com/chapters/ofdm2.pdf> 18/1/2012
6) No author given “super high frequency” 2004 Argos press http://www.argospress.com/Resources/CommunicationsSystems/suphighfreque.htm 18/1/2012
7) Tomislav Stimac “Definition of frequency bands (VLF, ELF... etc.)”(n.d) http://www.vlf.it/frequency/bands.html 17/1/2012
8) William C. Shiel Jr “Magnetic Resonance Imaging (MRI Scan)” Medicine net http://www.medicinenet.com/mri_scan/page2.htm 18/1/2012
9) David Rotham (2009) “Radio waves: Future way to help keep e-book readers charged up?” Tele read http://www.teleread.com/ebooks/radio-waves-way-to-help-
keep-e-book-readers-charged-up/ 19/1/2012
10) Edwin Cartlidge (2011) “Twisting Radio Waves Could Give Us 100x More Wireless Bandwidth” http://discovermagazine.com/2011/oct/13-twisting-radio-waves-100x-
more-wireless-bandwidth 20/1/2012.
Images
Title page:http://www.robertopiecollection.com/Application/Products/Bush-radios/bush-radios-1GB.asp & http://forums.techarena.in/web-news-
trends/995783.htm
Figure 1http://news.bbc.co.uk/1/hi/technology/7646348.stm
Figure 2http://www.kitguru.net/channel/carl/sony-recall-1-6-million-bravia-tvs-due-to-fire-risk/
Figure 3 http://forums.techarena.in/web-news-trends/995783.htm
Figure 4 Image created by myself.
Figure 5http://www.maplin.co.uk/185cm-satellite-dish-47165
Figure 6http://www.gsmarena.com/apple_iphone_3g-pictures-2424.php
Figure 7 http://www.prlog.org/11292973-codaoctopus-colmek-receives-unique-radar-production-contract-from-major-defense-prime.html
