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Shortened directional coupler using slow wave structure of periodically loaded capacitance and inductance
Author(s) -
Zhong Cuilin,
Yu Fengqi,
Sun Yuanpeng,
Nie Wei,
Wang Maoyan
Publication year - 2015
Publication title -
international journal of numerical modelling: electronic networks, devices and fields
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.249
H-Index - 30
eISSN - 1099-1204
pISSN - 0894-3370
DOI - 10.1002/jnm.1961
Subject(s) - capacitance , power dividers and directional couplers , inductance , stub (electronics) , hybrid coupler , electrical impedance , equivalent series inductance , transformer , acoustics , equivalent circuit , electrical engineering , physics , electronic engineering , engineering , voltage , electrode , quantum mechanics
This paper proposes an analytically based approach for the design of a length‐reduced directional coupler. This method of reduction is realizing the directional coupler's impedance transformers by using slow wave structures. These slow wave structures are designed by transmission lines periodically loading both shunt capacitances and series inductances. Loaded capacitance is realized by stub shunt capacitance on the top layer; at the same time, loaded inductance is realized by electromagnetic band gap structure on ground. Increasing parallel capacitance and series inductance can reduce the phase velocity of the propagating waves and hence engender higher electric lengths using smaller physical lengths. A directional coupler is designed using this slow wave structure, and the performance of coupling is analyzed with the generalized coupled‐mode theory. The design methodology is validated with the design of a length‐reduced directional coupler at 0.7 GHz. An approximate length reduction of 54% is achieved with this technique compared with the conventional directional coupler. The electromagnetic simulation and experimental results validate the proposed approach. Copyright © 2015 John Wiley & Sons, Ltd.