Simple CAD Models for Novel $50\ \Omega$ and $75\ \Omega$ Cylindrical Stripline Couplers

In the present work, simple computer-aided design (CAD) models are reported to design novel $50\ \Omega$ - and $75 \Omega$ -cylindrical stripline directional couplers (CSC). We have based on rigorous analysis by the finite element method (FEM) to derive the analytical models. As application, $50\ \Omega$ - and $75\ \Omega$ -CSC couplers with 20- and 30-dB of coupling, operating respectively at 4- and 2.5-GHz, have been designed, showing very good agreement between numerical and analytical results. The couplers designed are of high directivity and of good isolation confirm the validity and the effectiveness of the proposed CAD models.