A Novel Via-free Microstrip Balanced-to-balanced Diplexer for Narrow-band Applications

In this article, a new type of microstrip vias-free balanced-to-balanced diplexer suitable for narrow-band applications is presented. The structure of the balanced diplexer is based on two balanced bandpass filters designed for f151.1 GHz and f251.8 GHz and two transmission lines used to satisfy the open circuit conditions required in the diplexer’s design. This diplexer exhibits good common-mode rejection ratio better than 40 dB at the passbands. The attenuation is better than 35 dB at the rejection bands. The isolation between output ports is better than 50 dB. Simulated and experimental results are compared with good agreement. The diplexer is easy of fabricate and integrate with others planar balanced devices. VC 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:567–570, 2015; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.28902