A compact dual-band coupler with arbitrary power dividing ratio using broadside-coupled microstrip

Abstract

In this paper, a compact dual-band coupler with arbitrary power division ratio using broadside-coupled microstrip has been proposed, designed, and measured. The proposed coupler is formed by two three-section microstrip lines and a common ground plane with three rectangular shaped slots used for coupling. Simple analysis method based on the even-odd mode technique has been applied, design equations are then derived. With the even- and odd-mode characteristic admittances, the initial geometry parameters of the proposed coupler are obtained by using the empirical formulas. The coupler features a wide frequency ratio range, arbitrary power dividing ratio, compact size, and wide bandwidth. For verification purposes, two prototypes of the proposed couplers with a coupling ratio of 3 and 6 dB, operating at the frequency of 2.4/5.2 GHz, have been designed, simulated, fabricated, and measured. Good agreements have been shown between the simulated and the measured results.

Acknowledgments

This work was supported by the National Basic Research Program of China under Grant 2009CB320206 and the National Natural Science Foundation of China under Grant 60901024.