DESIGN & IMPLEMENTATION OF BRANCH LINE COUPLER USING ADS

Abstract

Branch line couplers one of the most famous passive circuits used for microwave and millimeterwave applications. Quadrature hybrids are good examples that gives equal amplitude and quadrature phase outputs at the desired frequency band. They are commonly used in balanced amplifiers and mixers for attaining good return loss, as well as spurious signal rejection. The goal of this project is to design, simulate, and fabricate the Branch Line Coupler operating at microwave frequency by using a software called “Agilent Advance design system (ADS)”. The Branch Line Coupler covers arbitrary band, that frequency decided by area of application. Todays, a good advancement in wireless communication is done because of increasing demand of users to access data services. To fulfill the data access demand, that only possible by increase spectrum of wireless communication system. But the spectrum given by authority is limited, and ranges also provided in bands e.g. 850MHZ, 900MHZ, and 2000MHZ. Hence, wireless communication system have multiple standards that’s results increasing demand of design multiband system. Therefore in recent year much consideration is given to new design of the couplers, operating at the two arbitrary frequency band. In this thesis, the design and implementation of a novel planar dual band branch line coupler is introduced. First we discussed Single-Band Branch Line Coupler design and then simulation on Agilent ADS. In order to translate these circuits for dual band, ABCD-parameter is employed. A detailed mathematical analysis of each design is analyzed. The ADS simulations were used to accurate determine the final design. The designed models are implemented using non-uniform microstrip lines in Agilent ADS and Agilent EMPro. Simulation results shows proposed models as good candidate for wide band microwave application. Finally, the fabrication of Branch Line Coupler is done using non-uniform microstrip line on a FR4 substrate.