An extensive line directional crossguide couplers from Microwave Development Labs includes three- and four-port waveguide designs available with Type N and SMA connectors on the secondary coupling arms. The couplers are available in all major waveguide bands, including WR51 for 15.0 to 22.0 GHz, WR28 for 26.5 to 39.0 GHz, and WR42 for 18.0 to 26.5 GHz. As an example, model 42XT326 is a three-port WR42 coupler that features mean coupling of 20 dB from 18.0 to 26.5 GHz with maximum VSWR of 1.25:1. The minimum directivity is 20 dB. The coupler, which is also available in versions with 30, 40, 50, and 60 dB coupling, can be designed with coupling in left-hand or right-hand direction. The total coupling flatness is maintained across the frequency range within 1 dB. For more information on these and other waveguide components, visit the MDL website at: http://www.mdllab.com/