Compact design of branch-line coupler based on CRLH TL combined with fractal shaped geometry

This paper presents novel 3-dB branch-line coupler by combining the technology of fractal geometry and composite right/left handed transmission line (FCRLH TL) for the first time. The designed branch-line coupler operating at 0.88GHz has been successfully designed. Simultaneously, the proposed FCRLH TL cell has been detailed investigated by the method of electrical parameters extraction process, and also accompanied by planar circuit simulation in order to provide an deep insight into the operation mechanism of it, and further more, numerical results show that the proposed coupler operated at the given frequency achieved a comparable 75.8% size reduction compare with previously design of coupler that has been reported so far, which show prospective application in miniaturization of microwave components.