A novel low cost structure of microstrip coupler 3dB

this paper presents a novel design of branch line (3dB, 90°) coupler, it is designed and simulated by using FR4 substrate at the operating frequency 2.45 GHz in the ISM “Industrial Scientific Medical” band. The design is based on two different models, the T-model and combinational-model (T- and π-model). After a theoretical study on the use of open stubs, we present the simulation results of this branch line coupler by using the ADS from Agilent technologies and CST Microwave Studio. Good agreement is found between simulated results using ADS and CST Microwave Studio.