Atmospheric Diffraction - Radio Wave Propagation in The Ionosphere

Radio Wave Propagation in The Ionosphere

The ionosphere is a layer of partially ionized gases high above the majority of the Earth's atmosphere; these gases are ionized by cosmic rays originating on the sun. When radio waves travel into this zone, which commences about 80 kilometers above the earth, they experience diffraction in a manner similar to the visible light phenomenon described above. In this case some of the electromagnetic energy is bent in a large arc, such that it can return to the Earth's surface at a very distant point (on the order of hundreds of kilometers from the broadcast source. More remarkably some of this radio wave energy bounces off the Earth's surface and reaches the ionosphere for a second time, at a distance even farther away than the first time. Consequently a high powered transmitter can effectively broadcast over 1000 kilometers by using multiple "skips" off of the ionosphere.

An exotic variant of this radio wave propagation has been examined to show that, theoretically, the ionospheric bounce could be greatly exaggerated if a high powered spherical acoustical wave were created in the ionosphere from a source on earth.