%0 Journal Article %T A short history of geophysical radar at Arecibo Observatory %A J. D. Mathews %J History of Geo- and Space Sciences (HGSS) %D 2013 %I Copernicus Publications %R 10.5194/hgss-4-19-2013 %X As Arecibo Observatory (AO) approaches its 50th anniversary, it is appropriate to review the many radars and ionospheric heaters that have been deployed on or near the 305 m dish and to summarize some of the innovative radar-based geophysical research that has resulted. The reasons William E. (Bill) Gordon developed the 305 m Arecibo dish are well known but are briefly reviewed. The early and then more recent radar/feed designs are reviewed as geophysical uses of Arecibo have evolved and as the full potential of the dish and nearby facilities was and is being realized from HF through S-band frequencies. This history surely has some gaps and there are a few mysteries. The community is encouraged to fill these gaps and to help complete the history. %U http://www.hist-geo-space-sci.net/4/19/2013/hgss-4-19-2013.html