Research In Microwave Circuits Simplify Dual CRLH Structure

In the recent twenty years, a lot of researches aiming at the design of metamaterials have been done in the domain of physics, electronics, material science and so on. Due to this kind of material, the conception of left-handed material has changed people’s view about the traditional electromagnetic theory. In2002, the realization of CRLII transmission line structure helps a lot for the microwave radio systems miniaturization and integration. Compared with the matured composite right/left-hand structure, its dual structure-the structure of the dual composite right/left-hand structure has been observed in recent years.The series branch of the equivalent circuit model of the left and right dual composite structure is an inductor in parallel with a capacitor, and the parallel branch is a capacitor in series with an inductor, this circuit model is right dual with the series and the parallel branch of the traditional composite right/left-hand transmission line. In this paper, the simplified structure is introduced based on dual composite right/left handed structure.The research is emphasized on the basic theory and transmission features of the SD-CRLH. By the means of simplifying the dual complex right left hand structure and introducing the planar spiral SD-CRLH structure, some directional couplers with this kind of structure are designed, including branch line coupler,180degree hybrid network, coupled line coupler with smaller size, wider bandwidth, less pass band insertion loss and other advantages. At the same time, a phase shifter of simplified structure is designed. These two kinds of devices perform well with some expected parameters’ results after a series of physical measurements, full-wave simulation and circuit simulation.In summary, based on the simplicity of dual composite right/left-hand structure theory, several microwave devices of good performance and high feasibility are designed to achieve the expected goals.