Eccleston, K.W.Ong, S.H.M.2010-01-122010-01-122003Eccleston, K.W., Ong, S.H.M. (2003) Compact planar microstripline branch-line and rat-race couplers. IEEE Transactions on Microwave Theory and Techniques, 51(10), pp. 2119-2125.0018-9480http://hdl.handle.net/10092/3352INSPEC Accession Number:7758696 DOI: 10.1109/TMTT.2003.817442Both branch-line and rat-race couplers are easily realized using planar circuit technology as they employ only transmission lines without additional components. However, as the electrical lengths of the transmission line elements are either 90 or 270 , such couplers consume a significant amount of circuit area. This paper shows the development of branch-line and rat-race couplers that use artificial transmission lines (ATLs) in place of conventional transmission lines resulting in significant size reduction. As the ATLs are constructed entirely from microstriplines, the couplers are easily fabricated using conventional printed-circuit processes. The design formulas developed for the ATLs are explicit. Full-wave simulation and experimental results were used to confirm the design approach for hybrids operating at 1.8 GHz. The frequency response of the proposed hybrids is similar to conventional hybrids.en©2003 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.artificial transmission lines (ATLs)branch-line couplerperiodically loaded transmission linesrat-race couplerJournal ArticleFields of Research::290000 Engineering and Technology::290900 Electrical and Electronic EngineeringFields of Research::290000 Engineering and Technology::290900 Electrical and Electronic Engineering::290902 Integrated circuits