# What makes radio waves refract?

What materials cause radio waves to refract? What are the radio IOR's of these materials?

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Since radio waves are just electromagnetic waves (within a defined frequency range), every material will refract radio waves according to Snell's law. Or am I missing something in your question? –  BNJMNDDNN Jun 20 '13 at 19:21

Radio waves refract – they effectively bend in the atmosphere – and it is the ionosphere e.g. 60 km above the surface where they do so. See e.g.

http://www.tpub.com/neets/book10/40e.htm

You may imagine the atmosphere to be composed of many horizontal layers with different values of $n$ and the refraction satisfies Snell's law.

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Correction: refraction takes place in every layer, not just ionosphere. –  Deer Hunter Jun 21 '13 at 3:54
Right. I agree. Even the tropospheric one is sometimes important exactly because the angle of propagation is almost 90 degrees so even small variations in $n$ may substantially change the direction of motion. –  Luboš Motl Jun 21 '13 at 8:29
In electronics engineering, we often combine refractive phase-shift effects with exponential decay with depth through a substance in a complex-valued dielectric constant. With some math gymnastics, engineers define a "loss tangent". The index of refraction is related to the dielectric constant as $n^2 = e$ (n is IOR, e is dielectric constant).