Table of Contents
International Journal of Microwave Science and Technology
Volume 2014, Article ID 486051, 6 pages
Research Article

Ultrawide Bandwidth -Hybrid-Coupler in Planar Technology

Institut für Hochfrequenztechnik und Elektronik, Karlsruhe Institute of Technology (KIT), Kaiserstraße 12, 76131 Karlsruhe, Germany

Received 3 February 2014; Revised 15 April 2014; Accepted 15 May 2014; Published 2 June 2014

Academic Editor: Yo Shen Lin

Copyright © 2014 Steffen Scherr et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


A new concept of an ultrawide bandwidth 180°-hybrid-coupler is presented. The ultrawideband design approach is based on the excitation of a coplanar waveguide (CPW) mode and a coupled slot line (CSL) mode in the same double slotted planar waveguide. The coupler is suitable for realization in planar printed circuit board technology. For verification of the new concept a prototype was designed for the frequency range from 3 GHz to 11 GHz, built, and measured. The measurement results presented in this paper show a good agreement between simulation and measurement and demonstrate the very broadband performance of the new device. The demonstrated coupler with a size of 40 mm × 55 mm exhibits a fractional bandwidth of 114% centered at 7 GHz with a maximum amplitude imbalance of 0.8 dB and a maximum phase imbalance of 5°.