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I am trying to understand how radio waves behave when reflected, refracted and diffracted. I have put together a list based on light which I think will be the same. Can anyone tell me the behaviour of radio waves in each case, or alternatively just confirm (a) whether the behaviour of radio waves is the same as light in each case, and (b) whether the list below is correct? (I did it this way to try to save people some work, rather than because I know the answer)

Refraction

  • Changes: direction, wavelength, speed, amplitude (unless total refraction, in which case not)
  • Constant: frequency/period, phase

Reflection

  • Changes: direction, phase, amplitude (unless total reflection, in which case not)
  • Constant: wavelength, frequency/period, speed

The unrefracted component of the wave is reflected, and vice versa.

Diffraction

  • Changes: Direction, phase (generally - different path lengths result in different phases), amplitude (seen as a total, possibly not, but at any given point it is less)
  • Constant: wavelength, frequency/period, speed

(Edited for typo)

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  • $\begingroup$ What do you think is is the amplitude of EM radiation? $\endgroup$ – HolgerFiedler Apr 10 '18 at 5:33
  • $\begingroup$ I'd see it as a measurement of the energy the wave carries. For light, that's brightness; for radio I'm a little less clear, though I think in AM it is used to encode for the sound wave. For example: In astronomy, amplitude of a light's wave is important because it tells you about the intensity or brightness of the light relative to other light waves of the same wavelength. It's a measure of how much energy the wave carries. cse.ssl.berkeley.edu/light/measure_amp.html $\endgroup$ – James Carlyle-Clarke Apr 10 '18 at 6:18
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    $\begingroup$ recommend you post this on the amateur radio stack exchange. this sort of thing is their bread and butter. $\endgroup$ – niels nielsen Apr 10 '18 at 8:12
  • $\begingroup$ @nielsnielsen, could be worth a go, thanks, though I saw this as more of a physics based question (what are the physical effects and changes) rather than an experiential question (how in your experience does the radio signal change). But both viewpoints could be useful. $\endgroup$ – James Carlyle-Clarke Apr 10 '18 at 10:31
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As with light, radio waves are electromagnetic waves. As a result, they would obey the same behaviour. The only issue is the wavelength. Radio waves have longer wavelengths (lower frequencies) than light. So if the particular phenomenon depends on the wavelength, then that would affect how the radio waves would behave. Keep in mind that some material properties, such as the refractive index (dielectric constant) depends on wavelength.

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  • $\begingroup$ OK, that's what I figured, thanks... now all I need to do is confirm that the list above is correct and I'm all good. $\endgroup$ – James Carlyle-Clarke Apr 10 '18 at 5:19
  • $\begingroup$ Radio waves are photons just like light. The issue is frequency $\endgroup$ – Bill Alsept Jan 15 at 0:46
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They are all made of individual photons, even radio waves. There is no difference other than the frequency of the photons which determines their energy. Photons reflect, refract and diffract no matter what their frequency are. Brightness has to do with intensity which is the number of photons.

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