A novel wide-band hybrid coupler using coupled-line power divider and improved coupled-line phase shifter

Abstract

A novel hybrid coupler aiming for wide-band applications is proposed in this paper. This hybrid coupler consists of a broadband Wilkinson coupled-line power divider and an improved wide-band coupled-line phase shifter. Taking advantage of the coupled-line section, the power divider achieves both compact circuit configuration and wide-band performance. In lieu of patterned ground plane and lumped capacitors, the coupled-line phase shifter can be constructed on a single-layer printed circuit board for wide-band operation. For this proposed phase shifter, the scattering parameters (S-parameters) expressions are derived and the optimal structural design parameters for achieving zero reflection coefficients are highlighted. After carefully choosing the circuit parameters, a new wide-band hybrid is constructed by combining a power divider and the proposed phase shifter. To verify against the theoretical calculation in terms of S parameters and phase information, a hybrid operating at 3 GHz is designed, simulated, and fabricated through microstrip technology. Close agreement is obtained between simulation and measurement results.

Acknowledgments

This work was supported in part by the National Natural Science Foundation of China (No. 61001060, No. 61201025, and No. 61201027), the Fundamental Research Funds for the Central Universities (No. 2012RC0301), and Open Project of the State Key Laboratory of Millimeter Waves (Grant No. K201316).