【作者】 刘传运；

【导师】 褚庆昕；

【作者基本信息】 华南理工大学 ， 电磁场与微波技术， 2010， 博士

【摘要】 等效的介电常数和磁导率同时为负值的左手媒质,颠覆了经典电磁学和传统光学,它的发现被认为是2003年度十大科学突破之一,是当前物理与电磁学研究领域中的前沿与热点问题。电磁波在左手媒质中传播时将显现与传统介质不同的奇异的电磁特性,因而受到了越来越多研究人员的青睐。作为一门新兴的前沿科学,左手媒质的研究在很多方面还不完善,在电磁特性分析、结构构造以及工程应用等方面还需要不断地完善和深入发展。本论文针对这些问题进行研究,主要创新之处有:第一,提出了一种二维平面宽带左手媒质结构,该结构在两个方向上的相对带宽均能达到61.6%以上,而中心频率结构单元电尺寸在0.095以下,其双负频段可以平移,结构简单,平面结构更易于加工制作。通过验证该结构的二维双负特性、后向波特性以及负折射特性说明了该左手媒质结构的有效性。同时,说明了该结构的对偶形式——补偿开口金属谐振环的基本特性及典型应用领域,通过在基片集成波导一侧的壁上加载补偿开口金属谐振环结构构造了一种小型的超宽带滤波器,该滤波器利用加载补偿开口金属谐振环可以在截止频率以下产生前向波通带的特性,使得滤波器尺寸减小了40%,同时保留了基片集成波导体积小、重量轻、容易加工和集成等优点。第二,阐述了左手传输线和复合左右手传输线理论,比较了对称型和非对称型复合左右手传输线网络的优劣,并提出了一种非对称型具有超宽带特性的共面波导馈电式复合左右手传输线结构和一种改进的对称型复合左右手传输线结构,该结构在保持平面结构易于加工制作的优点之外,具有更小的尺寸,并且避免了微带交指电容易产生寄生谐振的缺点。探讨了复合左右手传输线结构的应用领域:从对复合左右手传输线的左右手通带分析出发,阐述了利用复合左右手传输线构造带通滤波器的机理,并且利用处于平衡态的对称型复合左右手传输线构造了一种超宽带滤波器,证明了该理论的正确性;阐述了漏波辐射的基本原理,指出相比传统漏波结构,复合左右手传输线漏波结构可以实现从后向到前向的连续辐射,并且不需要复杂的馈电网络。最后利用一种对称型复合左右手传输线结构构造了一种漏波天线,并通过数值仿真、等效电路分析和实际测试证明了该天线从后向到前向的连续双边辐射能力。第三,阐述了对偶复合左右手传输线理论,提出了一种对称型对偶复合左右手传输线结构,利用该结构的带阻特性实现了一种带阻滤波器,同时利用对偶复合左右手传输线结构的寄生效应,构造了一种能够实现从后向到前向的连续辐射的漏波天线,该天线同样不需要复杂的馈电网络。更多还原

【Abstract】 The emergence of the left-handed metamaterial (LHM) with simultaneously effective negative permittivity and permeability has subverted the classical Electromagnetics and the traditional Optics. The discovery of LHM has been regarded as one of the ten most significant discoveries in science community in 2003, and has been the front and focus area in physics and electromagnetics research. Compared with traditional materials, electromagnetic waves transmitted in LHM will behave some fantastic characteristics, which have attracted more and more attentions of numerous researchers. However, the research on the LHM is just at its exploration stage, and there are still many tasks need to be complete, including analysis of the exceptional EM properties, construction of the high performance LHM structures and their applications to microwave engineering. The main contributions of the dissertation can be summarized as follows.Firstly, a 2-D planar LHM with broad bandwidth is proposed. Its relative bandwidths are above 61.6% and the unit cell electrical sizes are below 0.095 along two dimensions. The frequency band where the LHM is applicable is tunable. The double negative property, the backward wave property and the negative index of refraction property are verified to prove the existence of the LHM. In addition, the characteristics and typical applications of complementary split-ring resonator (CSRR), which is the dual structure of the 2-D planar LHM, are described. An ultra-wideband filter which is composed of CSRRs etched on the surface of a substrate integrated waveguide (SIW) is proposed. By using the characteristics of CSRRs resonant below the waveguide cutoff frequency, an additional forward passband below the waveguide cutoff can be obtained. So the filter size decreases by 40%, while maintaining the advantages of SIW, such as small size, light weight, easy processing and integration, etc.Secondly, the ideal left-handed (LH) and composite right/left-handed (CRLH) transmission line (TL) theory are detailed. The asymmetric and symmetric CRLH TL networks are compared. Then an asymmetric coplanar-waveguide-based CRLH TL structure with ultra-wideband and a modified symmetric CRLH TL structure are proposed. These structures have planar structure and compact size which make them easier to implement in diverse miniaturized components. Furthermore, the undesired resonances of the interdigital capacitor, due to the multiconductor structure, are removed. Some applications of CRLH structure are presented. For one thing, by analyzing the left-handed and right-handed passband, the mechanism of the application of the CRLH TL in bandpass filter is proposed. Using the symmetric CRLH TL structure, an ultra-wideband filter is proposed, by which the mechanism is confirmed. For another, the principle of leakage radiation is illustrated. The advantages of the CRLH leaky-wave antenna compared with conventional leaky-wave antenna are given: the capability of backfire-to-endfire frequency-scanning and simple feed mechanism. A double-side radiating leaky-wave antenna based on the symmetric CRLH TL structure is proposed. The numerical simulations and experimental measurements are used to confirm the performance of the antenna.Finally, the ideal dual-composite right/left-handed (D-CRLH) transmission line (TL) theory is detailed. A symmetric D-CRLH TL structure is proposed. While a D-CRLH TL is band-stop in nature, a band-stop filter is constructed. Furthermore, by utilizing the presence of parasitic effects, a leaky-wave antenna with backfire-to-endfire radiation capability is proposed. This antenna also has a simple feed mechanism.更多还原