Novel CRLH TL based on fractal geometry and series power divider application

Abstract

A novel resonant-type composite right/left handed transmission line (CRLH TL) and its correlative lumped-element equivalent circuit model are presented based on complementary single split ring resonator pair (CSSRRP). The circuit model is investigated in depth through the Bloch theory, and the condition for balanced CRLH TL is derived. The negative refractive index and the backward wave propagation are demonstrated by the effective electromagnetic parameter retrieval. After that, a balanced electrically small CRLH TL with zero phase shift is designed at WiMAX (Worldwide Interoperability for Microwave Access) band by introducing the Koch fractal geometry into CSSRRP. For application, a series power divider is fabricated and measured. Consistent simulated and measured results confirm the design concept. The bandwidth of the proposed power divider is broadened by 56%, and the overall dimension is only 58% of its conventional counterpart based on meandered line. Thus novel CRLH TL based on fractal shape CSSRRP can be found to have an extensive application in future small-size wireless communication system.