A NEW METHOD FOR ACCURATE IONOSPHERIC ELECTRON-DENSITY MEASUREMENTS BY INCOHERENT-SCATTER RADAR

It is shown that the detectability of the plasma line in incoherent scatter radar experiments on the ionospheric plasma can be increased by factors in the range of 10-100 by chirping the transmitter frequency at a rate matching the rate of change of plasma frequency with height. The method is explained in detail, and some initial experiments carried out at the Arecibo Observatory are described. Plasma frequency versus height profiles with an accuracy better than one part in 10**3 were established with 1-s integration time per point. An example of quasi-periodic oscillation of ionospheric electron density with a period of about 18 min is also shown.