Research On Performance And Application Of Metamaterial In The Microwave Devices

In recent years, metamaterials has become one of research area where researchers in physical and electromagnetic disciplines actively explore. Its dielectric constant or magnetic permeability in a particular frequency is negative, which represents negative refraction characteristics. With the rapid development of wireless communication related field, communication equipments are becoming tinier and tinier, more and more convenient, which brings about a challenge to design smaller, more excellent microwave devices. The application of metamaterials into microwave devices not only can reduce the size, but also may improve the performance of microwave devices. In this article, therefore, the property and application of metamaterials in microwave devices is deeply researched.The structure of metamaterials consists of resonance structure and Composite Right/Left Handed(CRLH) transmission line structure, the characteristics and application in microwave devices of the two metamaterials structure are studied in this paper. It is can be seen from the equivalent circuit model of Split Resonant Rings(SRRs), Spiral Resonators(SRs), Complimentary Split Resonant Rings(CSRRs) and Complementary Spiral Resonators(CSRs) that increasing the equivalent inductance or equivalent capacitance of resonator can reduce their resonance frequency, in the other words, loading metamaterials resonance structure into microwave devices can decrease the resonant wavelength of microwave devices to realize miniaturization. The research focus is multiple-ring CSRRs and three-level CSRs, and it is demonstrated that they are beneficial to the miniaturization of microwave devices from the simulation and testing results. Based on the research above, three miniaturized diplexer based on substrate integrated waveguide and loaded by CSRRs or CSRs are designed, the test results are consistent with simulation results. Their size is same and only reach one third of the diplexer’s size without CSRRs or CSRs. On the other hand, the CRLH transmission line structure method and its dispersion characteristic are studied in this paper, and then the balance condition requirement of CRLH transmission line and its characteristic are discussed. A novel CRLH transmission line structure is proposed, which is implemented by loading interdigital capacitor on both the front mental and ground layer of Half Mode Substrate Integrated Waveguide(HMSIW), and it produces two resonant frequency points with metamaterials characteristics below the cut-off frequency of HMSIW. The two metamaterials resonant frequency points have 90 o phase difference between the two ports, just like traditional quarter-wave transmission line. However, there is a resonant frequency points with 90 o phase difference upon the cut-off frequency. This characteristic can be used in the design of dual-band microwave devices. And at last, based on the porposed CRLH transmission line, a dual-band hybrid ring coupler is proposed and is verified by simulation and testing.