Design and Implantation of a Wideband Microstrip 90° Hybrid Using Quasi-Π-Shaped Structure Loading

This paper presents the design and implantation of a wideband microstrip branched hybrid coupling. The wideband performance of the hybrid means that it possesses equal coupling and difference of phases throughout the operating frequency band, from 3.5 GHz to 6.5 GHz. The compactness of the proposed design is depending on the replacement of branched transmission lines instead of conventional transmission lines. Small and easy to fabricate microstrip layout topology for the hybrid have been designed and constructed relying on a low cost dielectric material, the well-known FR4. In addition, the proposed hybrid can be easily fabricated on the printed circuit board without any lumped element. The proposed hybrid exhibits couplings and phase errors within −3.5 ± 0.75 dB and 4° over a 70% bandwidth with a center frequency of 5 GHz.

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