Coherent backscatter from ionospheric E-region plasma irregularities

The principles of coherent backscatter from irregularities created by plasma instabilities in the ionospheric E-region are described in this paper. It is intended as an introduction for readers who are not familiar with this subject and not as a review article. The general principles of radar backscatter are outlined as well as the nature of plasma instabilities that cause the irregularities. In subsequent sections the occurrence of the irregularities at different geographical latitudes is addressed and the spectrum of the backscatter is discussed. Finally, some applications, particularly of auroral radars, are briefly mentioned.