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Analytical method for optimal design of RF dual‐band rat‐race couplers for arbitrary frequency ratios
Author(s) -
Aflaki Pouya,
Ghannouchi Fadhel M.,
Negra Renato
Publication year - 2012
Publication title -
international journal of rf and microwave computer‐aided engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.335
H-Index - 39
eISSN - 1099-047X
pISSN - 1096-4290
DOI - 10.1002/mmce.20648
Subject(s) - multi band device , rat race coupler , microstrip , microwave , electrical impedance , transmission line , frequency band , radio frequency , radio spectrum , topology (electrical circuits) , hybrid coupler , electronic engineering , dual (grammatical number) , physics , computer science , engineering , electrical engineering , power dividers and directional couplers , telecommunications , antenna (radio) , art , literature
This article presents an analytical method to design a hybrid structure dual‐band rat‐race coupler at microwave frequencies. The proposed structure uses six identical cells of which each is engineered to work as a quarter wavelength transmission line with proper characteristic impedance at two distinct frequencies having arbitrary frequency ratio. The performances of the π‐ and T‐cells are studied to assess their ability to provide the required electrical parameters for dual‐band operation. It is demonstrated that the single‐section π‐topology can only lead to a suboptimal design for a dual‐band rat‐race cell at two nonharmonic frequencies. In contrast, the proposed double‐section π‐cell structure allows achieving an optimal dual‐band cell design. A dual‐band rat‐race coupler designed at 2.14 and 3.6 GHz has been simulated and fabricated in hybrid microstrip technology. Measurement results agree well with analytically based simulation results, which demonstrate the effectiveness of the proposed structure for dual‐band operation. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE 22: 690–700, 2012.