Design Theory of Open-Circuited Interdigital Couplers with Asymmetrical Cross-Section

Takeshi OSHIMA  Hideyuki OH-HASHI  Naofumi YONEDA  Masataka OHTSUKA  Moriyasu MIYAZAKI  Shigeru MAKINO 

Publication
C - Abstracts of IEICE TRANSACTIONS on Electronics (Japanese Edition)  Vol.J90-C  No.4  pp.344-350
Publication Date: 2007/04/01
Online ISSN: 1881-0217
Print ISSN: 1345-2827
Type of Manuscript: PAPER
Category: 
Keyword: 
couplers,  asymmetry,  interdigital,  c mode,  π mode, 

Full Text(in Japanese): PDF(274.4KB)

Summary: 
On open-circuited interdigital couplers with asymmetrical cross-section, matching condition for a coupled quarter wavelength long and formulation of fractional bandwidth which satisfies that condition are derived utilizing a coupled line theory on c and π modes. These formulations are expressed with terminated impedances at input/output ports and line capacitances per unit length which give the transmission characteristics of couplers with axial uniformity. As an example, the reflection characteristics of broadside interdigital coupler with asymmetrical cross-section are represented by numerical evaluation, and the validity of derived formulations is also verified, and in addition, the relation between terminated impedances or coupling capacitance and fractional bandwidth is made clear using these formulations.