PROJECT TITLE :

Improving isolation of slot-coupled directional couplers with weak and tight couplings

ABSTRACT:

A appropriate technique for improving the isolation of slot-coupled directional couplers with elliptical-shaped slot and patches is introduced. It is shown that the even- and odd-mode section velocities rely on the width of the patches and slot of the slot-coupled directional couplers. For couplers with tight couplings, the even- and odd-mode section velocities will be effectively equalised by cutting some parallel slots into the patches, while for couplers with weak couplings, the even- and odd-mode part velocities will be equalised by cutting some teeth into exterior part of the slot within the common ground plane. For numerous slot lengths and tooth depths, various style graphs are derived by sweeping some dimensions of the coupler. On the idea of the look graphs, 3 couplers with tight, moderate and weak couplings are designed and simulated. The designed coupler with tight coupling is also made and tested. The results show that by employing the proposed method, the isolation of the slot-coupled directional couplers has improved significantly.