• Question: What is a radio signal? and how do you change them and see how they react to things?

    Asked by pinkshoe to Akram, David, Gill, Jack, laurenceharwood on 19 Mar 2012. This question was also asked by lollipoplover.
    • Photo: Akram Alomainy

      Akram Alomainy answered on 19 Mar 2012:

      Thanks for the wauestion which is really interesting …

      Radio waves are basically small electrons or particles travelling everywhere in space … we use antennas to radiate them so let them go crazy and also to catch them and guide them to our circuits and devices! When we say we change radio waves we mean that we need to see how long they travel for and if we add a big metal plate what happens to it does it go through or all reflect back!

      Interestingly if you take your mobile phone to the lift and you are totally enclosed then your signal level becomes really weak and that is because metal does not let radio signals through it …

      They are invisible waves but we use computer models and thanks to great scientists like James Clerk Maxwell we can use maths to see them on computers and how they actually behave so we use that to test our theory and how they behave around humans then we take it to the lab and see if we receive power levels from all directions as the computer told us …

      Here is some interesting plots about that … http://www.elec.qmul.ac.uk/antennas/ubicomp.html

    • Photo: Gill Menzies

      Gill Menzies answered on 20 Mar 2012:

      The world would be a very different place without radio signals – they are used for broadasting, communicatons, computer networks …..They are a type of elecromagnetic radiation that travels at the speed of light. Very short wavelengths travel along a line of sight which is why your favourite radio station disappears off the car radio when you go away on holiday……Some wavelengths reflect off the upper atmosphere (called the ionisphere) and can travel around the world.

    • Photo: Jack Snape

      Jack Snape answered on 20 Mar 2012:

      Radio waves are the same kind of radiation as light … called electromagnetic radiation. The difference between radio waves and visible light is that radio waves have much longer wavelength. It is the very long wavelength that helps them spread out around mountains and large buildings so they can travel long distances!

      Akram, I’m sorry if I seem argumentative but when you say “Radio waves are basically small electrons…” that is actually wrong. Radio waves are electromagnetic radiation and if you want to describe them as a particle, they are called ‘photons’ not ‘electrons’ … Electrons can cause radio waves by moving in an antenna so it’s definitely a good idea to mention them 🙂

    • Photo: Laurence Harwood

      Laurence Harwood answered on 21 Mar 2012:

      Radio waves are part of the electromagnetic spectrum which starts with cosmic rays (shortest wavelength, highest energy) and goes through X-rays, ultra-violet, visible, infra red, radio waves and television waves (longest wavelength, lowest energy). The longest waves are:
      10,000,000,000,000,000,000 times longer than the shorted so this is a huge range.

      There are machines available that can shorten or lengthen the wavelengths of electromagnetic radiation and we know how we can interact with them – we can just turn on a radio. The oscillating wave (one way we can think of electromagnetic radiation) sets up a small voltage difference along a conductor and this can be detected.