Modifying branch-line coupler design to enhance six-port reflectometer performance

Abstract

Hybrid couplers are commonly utilized as the building blocks of six-port reflectometers but unfortunately the resulting instruments do not comply with the optimum design specifications. A previous attempt to rectify this defect employs modified rat-race couplers which are not easy to inter-connect during reflectometer fabrication. The present paper considers the use of modified branch-line couplers as a simple alternative so as to capitalize on their compact-size advantage for reflectometer design. © 2009 IEEE.