This document comprises recommended practices for the measurement of antenna transmitting and receiving properties. It is a comprehensive revision and extension of ANSI/IEEE Std 149-1979 (Revision of IEEE Std 149-1963) IEEE Standard Test Procedures for Antennas. Throughout this standard it may be assumed that the antenna to be measured can be treated as a passive, linear, and reciprocal device. Therefore, its radiation properties can be measured in either the transmitting or the receiving mode. Many of the test practices described can, however, be adapted for use in the measurement of antenna systems containing circuit elements that may be active, nonlinear,or nonreciprocal. For these cases, there is no simple relationship between the antenna systems transmitting and receiving properties. Therefore, measurements should be performed for the mode or modes in which the antenna system has been designed to be used. A fundamental property of any antenna is its radiation pattern. The measurement of radiation patterns in an antenna test facility is discussed. The design of antenna test facilities is described along with instrumentation requirements for the proper operation of the antenna facility, directions for the evaluation of an (existing) range, and the operation of ranges is discussed. For each direction of space, the radiation pattern is characterized by amplitude, phase, and polarization. From the measurement of these parameters, gain, directivity, and radiation efficiency can be determined. Power transfer from generator to antenna is controlled by the input impedance to the antenna. This important parameter frequently limits the useful bandwidth of the antenna. Measurement procedures and network descriptions for antenna impedance are described. Measurement of the radiation pattern includes errors. A method of uncertainty analysis is presented and discussed for its applicability to the various test facilities described. Throughout this standard, attempts are made to discuss measurement techniques as thoroughly as is practicable. However, in general, step-by-step procedural descriptions have been avoided. References are provided that are illustrative of measurement techniques and in which details may be found.