A Miniaturized Microstrip Branch-Line Hybrid Coupler Using Two Sections and Coupled-Lines

In this paper, a miniaturized microstrip 3dB quadrature branch-line hybrid coupler (QBLHC) is presented for size reduction. The proposed QBLHC is composed of single coupled-lines, parallel coupled-lines, and cascaded two sections in structure, which gives the wider operation band, good impedance matching, and the excellent isolation. By comparing with conventional microstrip 3dB quadrature hybrid coupler, the proposed hybrid coupler has 77% size reduction at the frequency band of 0.65~1.05GHz with almost equivalent electrical performance.