Electronic Fact of the Day

Induction and Radiation Fields

There is a mix of magnetic and electric induction fields and an electromagnetic radiation field at distances that are small compared to the size of a transmitting antenna or a wavelength. The two induction fields differ in phase and are stronger in magnitude than the radiation field near a transmitting antenna. The magnetic field strength from a doublet is inversely proportional to square of the distance. The electric field strength from a doublet has two components. One diminishes inversely proportional to the square of the distance. The other diminishes inversely proportional to the cube of the distance. However, the radiation field strength diminishes inversely proportional to the distance, so both induction fields diminish faster than the radiation field with distance.

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