Waveguide directional couplers feature low insertion loss, a flat coupling level and high directivity. The below standard models cover 18 to 110 GHz, however, additional models are offered for frequencies up to 170 GHz. Mechanically, they are constructed as either waveguides or split blocks. While the waveguide version offers the advantage being light weight with a flexible coupling arm orientation, the split block version offers a compact size and higher directivity. Three types of couplers are offered: standard directional (3 ports), bi-directional (4 ports) and dual directional (4 ports).