In 1969, IEEE Standard 145 was published as a list of basic terms of antenna theory and
practice. That document treated antenna gain as a fundamental property, with impedance and
polarization as independent properties. The definitions of gain, directivity, impedance, and
polarization were worded to emphasize this independence. Various other significant groups of
terms were also defined, such as the regions of the electromagnetic field of an antenna, the terms
relating to cross section, the tracking antenna techniques, and the idealized radiators.