This Test Procedure, which supersedes the previous issue, Standards on Antennas--Methods of Testing 48 I R E 2S2, is concerned with measurements of the properties which characterize antennas. In Section 1.2, symbols and units to be used in this test Procedure are defined. The effect of the environment on the antenna and its characteristics is discussed in Section 1.3, and certain precautions to be taken during the measurements are suggested. In Section 1.4, the usefulness of the reciprocity theorem in antenna measurements is cited, along with examples of situations in which this theorem does not apply.