Design of ultra wideband 3 dB coupled-line coupler and 90° power divider with zig-zag-shaped slot for wireless communication applications

Abstract

This paper proposes the new design of compact ultra wideband (UWB) 3 dB coupled-line coupler and 90° power divider. The proposed coupler utilizes zig-zag-shaped slot at the ground plane underneath microstrip coupled-line to enhance the bandwidth and coupling strength significantly. The technique has alleviated the need of a very narrow spacing between parallel coupled-line for easier fabrication process. The proposed coupler is then being implemented into the new proposed structure of 90° power divider that requires an appropriate phase difference of −90° with equal power division across UWB frequency range. The design of 3 dB coupled-line coupler and 90° power divider are realized using Rogers TMM4 substrate, which simulated by using CST Microwave Studio. Excellent UWB performances are achieved in terms of input reflection coefficient, isolation, coupling factor and transmission coefficients.