Research & Design Of One-Dimensional Microstrip PBG Struture

Since the new concept Photonic Crystal has been put forward by Yablonovitch and John independently in 1987, the application of photonic band gap (PBG) structures in the MMIC (Microwave and Millimeter-wave Integrated Circuits) have emerged as a hotspot for research and development. At present, great evolvements of relative theory and experiments about this domain have been obtained overseas. Along with the growth of the research of PBG structures overseas, significant attention was aroused in China. However, the research of PBG in our Country developed later compared with other Countries and there are still disparities in some way. Thus, the research of this work is important and necessary. This work was supported by National Science Foundation of P. R. China and the project for Science and Technology leader of Si Chuan Province.The place that exists in PBG structures is similar with the band gap in semiconductor, called photonic band gap, which means propagation of electromagnetic waves of certain frequencies in photonic band gap is prohibited. PBG structures have enormous advantages that can't be substitutable in the easier integration, greatly reduced hardware size, weight as well as cost of microwave circuits. The special characteristic of PBG structures put the MMIC forward into a new field, which will present us a wider application foreground.Firstly, the influence of different factors including unit size, periodic numbers, unit figure, the permittivityε_r of substrate and periodic distance on characteristics of PBG structures were discussed in this paper. Then, the material and size of the substrate were determined by the discussion mentioned above. After that, based on the analysis of traditional one dimensional round and ring PBG structures, the round and square split ring PBG structures were designed. And these two new structures are both easy to realize. The performance of these structures were all simulated by HFSS (High-Frequency Structure Simulator). Results show that the PBG structures with circular ring pattern are easy to realize and can get wide passband as well as small ripple. Square split ring pattern with two splits has good characteristics of passband, smaller ripple and insertion loss within passband, and deeper stopband (reached -62 dB). The square structure reduced the influence of the high order harmonics and has the best performance, so it will be widely applied in MMIC.