Waveguide branch couplers for tight couplings

Full-wave optimization design of waveguide branch couplers is presented. Waveguide T-junction equivalent circuit parameters are extracted from full-wave modeling results. They are used to explain why tight couplings are difficult to realize using waveguide branch couplers. Approaches used to obtain tight couplings are discussed and illustrated by two design examples of 3-dB couplers. Through random tolerance analysis, it is found that reasonable manufacturing tolerances have no significant effect on coupler performance.