Polar patch was the name given originally to a spatially limited enhancement of the 630-nm emission observed in the dark polar cap. More recently, the term has been applied to related phenomena observed by other experimental techniques. The interrelationship between patches observed by differing methods has yet to be determined fully. In this paper the signatures of a series of polar patches observed by Halley HF radar and the South Pole broad-beam and imaging riometers are presented. Most frequently, the HF radar patch signature immediately precedes that of the riometer polar patch signature. The interpretation is that the leading edge of the electron concentration structure that forms the patch is steeper than its trailing edge. On a few occasions, HF radar polar patch signatures coincide with the trailing edge of riometer patches and sometimes are seen throughout the riometer patch. Halley digital ionosonde data are used to show that riometer patches are more common over South Pole when the maximum F region plasma concentration is considerably in excess of 5¿1011 m-3, which often occurs in the afternoon plasma convection cell. ¿ 1999 American Geophysical Union