Waveguide transitions are mainly offered as either rectangular waveguide taper transitions or rectangular to circular waveguide mode transitions. While catalog models only list taper transitions between adjacent waveguide sizes, transitions between non-adjacent waveguide sizes are available upon request. Similarly, the catalog models only list mode transitions between standard rectangular waveguides and their corresponding midband circular waveguide. However, standard rectangular waveguides to high- and low-band circulator waveguides can also be requested. The taper implemented in the standard models is “linear” type. The below standard models are manufactured by using either EDM machining or electro-forming techniques to ensure high accuracy and a quality surface finish. While the listed models cover 18 to 110 GHz, additional models can be offered for frequencies up to 170 GHz or even higher bands. Typically, these transitions induce a fraction of a dB insertion loss and a VSWR of 1.05:1 or better when operating in the dominant mode.