Design and cross-section analysis of wideband rectangular-shaped directional coupler

This article presents the design of three-section rectangular-shaped directional coupler, which offers a tight coupling of 3 dB over the designated frequency band of 2 to 6 GHz. The proposed coupler was consisted of two substrates and one common ground plane between the two substrates. The proposed design was formed by rectangular-shaped microstrip line at the top and bottom with rectangular slot at the common ground plane. The overall dimension of the designed directional coupler, excluding microstrip ports occupy an area of 50 mm × 20 mm. CST Microwave Studio simulator was used to design and optimize the coupler. The cross-section analysis was performed in order to study the characteristic of electric field during the odd and even-mode excitation of the coupler.

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