The history of the study of radiation characteristics from certain simple apertures, which extends at least from Lommel (1884) to the recent work of Zemanek (1971), is summarized. Theoretical and experimental data concerning resolution, minor lobe behavior, and axial pressure level as a function of range in the near‐ to farfield transition region are presented and compared for a circular disk and a strip line transducer. The use of near‐ to farfield information in transducer calibration, range determination, and sonar design, is discussed.