Meteor scatter

Related wiki pages Bands, Propagation, Aurora, Tropospheric ducting

What is it?
The Earth moves in a roughly elliptical path around the sun. Whilst moving along this path, the Earth encounters many thousands of particles known as meteors. These vary in size from microscopic to large enough to pass through the atmosphere and hit the surface - these are known as meteorites.

Once meteors enter the atmosphere, they begin to burn up due to the friction caused by the density of the atmosphere. This causes a stream of ionised particles - sometimes of sufficient density for radio waves to be reflected. The degree of ionisation is dependent on the size of the meteor, hence the frequencies that are reflected are also dependent on this,

Generally frequencies between 20MHz and 500MHz are reflected by meteor inoisation.

Because meteors are usually in the atmosphere for no more than a few minutes, meteor scatter occurs in brief windows and is dependent on


 * the size of the meteors
 * the altitude at which the ionised stream is created
 * the location over which the meteor is falling
 * the angle of entry of the meteor
 * the relative positions of the stations

How is it used?
Because of its brief and unpredictable nature stations that experiment with meteor scatter use the following:


 * repeated signals are transmitted continuously over a long period of time
 * because of the brevity of the effect, a signal report may take some time to be received
 * a complete exchange of information may take some time to complete
 * Single Sideband is a popular mode for meteor scatter communications
 * Morse Code is often used due to the brevity of communications
 * WSJT software is often used by amateurs involved in meteor scatter communication

Links

 * International Meteor Organization