An improved version of a monostatic acoustic minisounder for the investigation of the structure and dynamics of the lower boundary layer, operating at high frequencies and equipped with a specially designed micro-antenna and advanced electronic circuits, is presented. This minisounder is shown to be capable of high resolution of less than 0.7 m and a minimum discernable height of less than a meter above ground. Examples of facsimile records under both convective and stable conditions obtained by the improved minisounder are given to demonstrate its capabilities.