A Novel Directional Coupler Loaded with Feedback Capacitances and Its Applications

Motomi ABE
Yukihiro TAHARA
Naofumi YONEDA

IEICE TRANSACTIONS on Electronics   Vol.E99-C    No.1    pp.85-94
Publication Date: 2016/01/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E99.C.85
Type of Manuscript: PAPER
Category: Microwaves, Millimeter-Waves
feedback capacitance,  coupled lines,  tandem 3-dB coupler,  stubs,  rectangular coaxial line,  8×8 HYB matrix,  

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A novel directional coupler loaded with feedback capacitances on the coupled lines is presented. Its effect of enhancing the coupling is qualitatively shown by deriving an equation for the coupling. Besides, a method to compensate for the phase difference between the even and odd modes of the coupler is presented. To demonstrate, a novel tandem 3-dB coupler consisting of the proposed coupled lines is designed and described. In addition, a waveguide (rectangular coaxial line) 8×8 HYB matrix using planar double-layer structure that is composed of the proposed tandem 3-dB couplers and branch-line couplers, which is operated in S-band, is designed and fabricated showing excellent performance.