B4. Analysis and design of single section and three-section ultra-wideband quadrature hybrid couplers

This paper presents analysis and design of two different slot coupled ultra-wideband quadrature couplers, employing a single section and a three-section configuration. A design procedure based on analysis of different design parameters of both circuit configurations is proposed. The simulation results of the single section coupler shows an amplitude imbalance ± 1dB form 4.8-10.6-GHz. The return loss and the isolation are better than 19dB and 25dB, respectively. The manufactured single section can exhibit 6° phase imbalance from 3-8 GHz. An improved three-section slot coupled hybrid coupler is designed by adding strips and slots of elliptical shape on the both sides of the tapered hexagon. The final circuit of three section coupler can exhibit a coupling of 3dB ±0.75 dB from 3.1-10.6-GHz. The corresponding return loss and isolation is the order of 22 dB and 26 dB, respectively. A phase deviation of ±1.8° between the ports is confirmed.