- Active. This series of standards provide specifications for the waveguide (including aperture dimensions, frequency range, cutoff frequency, etc.). It considers the tolerances of the waveguide aperture dimensions and the effect these have on the electrical properties (in terms of return loss, transmission loss, etc.) of the waveguide. It considers the tolerances of the waveguide interface dimensions and the effect these have on the electrical properties (in terms of reflection coefficient) of the waveguide. Recommendations for summarizing the performance and the expected uncertainty of the reflection coefficient of rectangular-waveguide apertures and interfaces for 110 GHz and above are provided. The information provided also facilitates the development of a complete uncertainty analysis for the performance of rectangular waveguide interfaces. This bundle includes: IEEE Std 1785.1-2012, IEEE Std 1785.2-2016, IEEE Std 1785.3-2016.