CSIW And Its Application In Filters And Antennas

Traditional microwave transmission lines,such as microstrip lines and rectangular waveguides are facing more and more challenges in today's communication system with increasingly higher frequency.The problems such as high loss,narrow bandwidth and large volume have become a huge gap that traditional microwave transmission lines cannot cross in the high frequency situation.Therefore,exploring the new microwave transmission lines with better transmission performance has become the focus of the whole microwave academic community.The performance of the microwave transmission line directly determines the whole communication performance of the high frequency communication systems in the future.As a new type of microwave transmission line,Substrate Integrated Waveguide(SIW)has attracted widely attention of experts and scholars because of its higher Q value,larger power capacity and easier integration with other planar circuits.But it's not only hard to process,but also difficult to integrate directly with active devices because of the two rows of metal holes,so this limits the application scope of SIW.Corrugated Substrate Integrated Waveguide(CSIW)is a new type of transmission line.It has most of the characteristics of SIW.CSIW replaces the metal holes of SIW with one-quarter wavelength branches,so it is easier to process than SIW and is also easier to integrated with active devices.The main achievements in this article are as follows: 1.Propose a mode-selective Corrugated Substrate Integrated Waveguide(MSCSIW)which combining the mode conversion characteristics of MSTL.MSCSIW has wider bandwidth than traditional CSIW and has the characteristics of mode conversion.MSCSIW works in quasi-TEM mode in the lower frequency,and gradually changes into quasi-TE10 mode in the higher frequency with the increase of frequency.In order to achieve the miniaturization of MSCSIW,a Half-mode MSCSIW(HMMSCSIW)was proposed.We can construct it by dividing MSCSIW into two sections.It has the similar transmission characteristics with full-mode MSCSIW,but the overall volume is reduced by half to achieve miniaturization.2.Explore the application of CSIW in filter field.Etch the EBG structure on the top surface of MSCSIW to form the stopband characteristic in a specific frequency band.It forms a low pass filter combined with the transmission characteristics of MSCSIW itself.Under the effect of EBG structure,the low pass filter has a wide low pass band and a deeper stop band.It effectively filters out the high-frequency electromagnetic waves outside the band.And it has the characteristics of mode conversion in the working passband.Then combine the SSPPs structure with MSCSIW.Study the dispersion characteristics of SSPPs unit and explore the influence of SSPPs structure on the transmission characteristics of MSCSIW.The filter's transmission performance can be controlled by changing the size of SSPPs unit.The practical application value of CSIW is proved through the design of the above two filters.3.CSIW is also applied in the antenna field in this article.CSIW is a single-layer dielectric structure,and it does not need to process metal holes through the medium.This reduce the difficulty of processing largely.CSIW can integrate with active devices directly such as PIN tube without the influence of the metal holes,and it can be used to design tunable antennas.Therefore,CSIW has many "innate" advantages in antenna design.A waveguide slot array antenna based on CSIW is designed in this chapter.The antenna etches slots of a certain size periodically to radiate the energy to the air.This is also an attempt for CSIW to design waveguide slot array antennas.