The index of refraction for materials in the radio frequency spectrum is determined by the square root of their relative permittivity. For instance, polystyrene has a relative permittivity of 2.6, resulting in a refractive index of 1.6 at 1 MHz. Water, with a relative permittivity of 78, has a refractive index of 8.8 at the same frequency. The relationship between radio refractive indexes and electrical permittivity is direct, unlike optical refractive indexes, which require permittivity values at optical frequencies.
PREREQUISITESResearchers, engineers, and students in the fields of electromagnetics, radio frequency engineering, and materials science will benefit from this discussion.
Also, can you please say what your target application is? What range of "radio" frequencies are you interested in? What kind of materials are you interested in? The better that you can ask your question, the better we can try to help you figure out the answers. Thanks.bbbl67 said:It's been stated that the index of refraction of materials varies with frequency throughout the EM spectrum. What are the index of refraction for various materials in the radio frequency?
Are radio refractive indexes just directly computed from their electrical permittivity? Optical refractive indexes don't seem to have such a straightforward relationship.tech99 said:The index of refraction (relative to vacuum) is the square root of the relative permittivity. For example, polystyrene, relative permittivity = 2.6 so refractive index relative to vacuum = sqrt 2.6 = 1.6 measured at 1 MHz.
Water, relative permittivity = 78 so index of refraction = sqrt 78 = 8.8 at 1 MHz.