The first measurements of speeds and decelerations using radial geometry were those of the Adelaide (Australia) group [9, 10]. The 54 MHz Buckland Park facility employing radial configuration provided accurate speeds (0.2 %) as well as decelerations and fragmentation event measurements. Examples of such down-the-beam-echoes are well presented in Elford  Figures 5 and 6.
The radio-astronomy instrument at Arecibo has been operated in meteor mode for limited periods. The 430 MHz facility employs a near-vertical pointing 305 m dish with principle focus steering deployed to scan up to 15° from zenith. Because of the high gain beam width of 0.16° the radiants of incident meteors can be located accurate to a fraction of a degree. The use of triple transmitter pulses yields enhanced precision and good meteoroid decelerations though the sky coverage is restricted: the antenna configuration provides limited viewing direction near zenith . Since the Arecibo instrument has a full astronomical programme dedicated meteor operation is limited.
The European incoherent scatter radar (EISCAT) operating at 930 MHz is an example of a system designed for ionospheric work that has proved valuable as a meteor probe, providing analyses of head echoes  and fluxes. A tristatic geometry (radars at Kiruna, Sweden, Tromso, Norway and Sodankyla, Finland) will enable trajectories and hence orbits to be secured .
Was this article helpful?