Design of Non-Quadrature Branch Line Coupler with Unequal Power Division using Asymmetric T-Structure

In this work, it is shown that non-quadrature branch-line couplers can be designed using asymmetric two-port networks of T-Structure instead of transmission lines as in the conventional branch-line coupler. The design equations of the proposed coupler have been obtained using the Y-matrix method. The primary advantage is that it provides design flexibility for equal and unequal power division with quadrature and non-quadrature phase differences across ports. A practical design of the proposed coupler has been implemented on FR4 Substrate.