Wideband quadrature hybrid coupler using microstrip to slot transition with multilayer technology

Abstract

This paper presents the planar design of three-section quadrature hybrid coupler for frequency operation of 2 to 6 GHz. This coupler offers a tight coupling of 3 dB and measured return loss better than 13 dB which occupies the size of 50 mm × 20 mm excluding the 50 ? SMA ports. The proposed quadrature hybrid design is implementing the microstrip-to-slotline transition with multilayer structure. The configuration of this design consists of two substrates layers and one layer ofa ground plane in the middle of the two substrates. Where, the proposed design is formed by rectangular-shaped microstrip line at the top and bottom with rectangular slot at the common ground plane. CST Microwave Studio software is used for coupler design and optimization. Then, the simulated results are compared to the measured results for verification. The characteristics of electric field for odd and evenmode are presented via cross section analysis of the coupler design.