| In recent years, there has been increasing interest in artificial electromagnetic materials, such as soft and hard surfaces, photonic crystals (PCs), electromagnetic band-gap (EBG) structures, double negative (DNG) materials or left-handed materials (LHMs), and artificial magnetic conductors (AMCs), because they all have novel electromagnetic features which may not occur in nature. These structures are broadly classified as metamaterials and their novel electromagnetic features have led to a wide range of applications in microwave fields to achieve high performance antennas and microwave components. Of all these artificial electromagnetic materials, AMCs have incomparable advantage and potential in antenna application, especially in achieving low profile antenna. Therefore, AMCs have expansive prospect in antenna application and are greatly worthy of research. In this dissertation, an in-depth study on AMCs is performed, and a unique polarization converting property of incident plane wave is found. Moreover, some compact structures with more applied value are designed and applied on classic antennas successfully.Firstly, two basic properties of surface wave band-gap and reflection phase band-gap are studied in this dissertation. The effects of all structure parameters on band-gap are analyzed, and some corresponding conclusions are obtained. For Asymmetric AMC structures, including rectangular and slotted structures, relation of reflection phase band-gap and incident wave polarization direction is studied. It is found that the reflection phase band-gap is only depend on the electric size of AMC cells in the direction of incident wave polarization, and is independent on the electric size in the perpendicular direction. In further, it is found the reflection phase band-gap is independent on the central vias of AMC structure. And so, a simpler strip type AMC structure is brought forward based on rectangular structure. Directional surface wave band-gap property of asymmetric AMC structures is studied, including rectangular, slotted and strip type structures. It is found the lowest frequency of band-gap, which is the highest frequency of propagated TM mode surface wave, is determined by the cell electric size in the direction of propagation. And the cell electric size in the perpendicular direction determines the highest frequency of band-gap, which is also the lowest frequency of propagated TE mode surface wave.The relation of incident wave polarized state and reflection phase band-gap of AMC structure with offset via is studied. For linear polarized incident plane wave, the polarization state of reflected wave can be linear polarization (the direction is parallel to incident wave), left-handed circular polarization, linear polarization (the direction is perpendicular to incident wave), right-handed circular polarization, which is termed polarization converting property. Feasibility analysis of application on stealth technique and significative research on achieving polarization converting of antennas are performed. For simple targets, with application of AMCs, there co-polarization radar cross section (RCS) can be decreased greatly. After reflected by paraboloid with AMC, linear polarized wave transmitted by feed source can be converted to left-handed or right-handed circular polarized plane wave with demand.Small size is the development trend of modern microwave circuit and antenna. Therefore compact AMCs can be applied more extensively. In this dissertation, at the foundation of basic property study, some compact AMC structures are designed successfully, including three-layer structure, cross shape structure, slotted structure and inter-embedded structure. There reflection phase band-gap and surface wave band-gap are studied, and there element size can be decreased about 50%, 15%, 30% and 70% respectively. In these structures, the inter-embedded AMC structure is the smallest one in all structures published in public.Utilizing its suppressing propagation of surface wave, AMCs are applied on linear, circular polarization microstrip antenna and microstrip antenna array successfully. Two linear polarization microstrip antennas are designed, which work at C-band and Bluetooth communication band respectively. With the application of a novel triangle grid AMC structure, back lobe of antenna is decreased about 15dB, and the gain is increased about 0.9dB, which is superior to antennas with square or hexagon AMC applied. In further, the effects of some parameters on antenna performance are analyzed, including distance between AMC and patch, the number of AMC layer, and some corresponding conclusions are obtained. With the AMC applied on circular polarization patch antenna, not only the gain is increased and the back radiation is decreased, but also the axial ratio band width vs frequency can be increased. By suppressing the propagation of surface wave, applying AMC on antenna array can decrease the mutual couple of antenna elements, and improve antenna performance, and enlarge scan angle of scanning antenna arrays.Using in-phase reflection of AMCs, low profile horizontal wire antenna and plane inverted F antenna built on AMCs are achieved successfully. Horizontal wire antenna with AMCs can radiate effectively, and its height is only 3.5mm, which is impossible on metal plane. Plane inverted F antennas are applied extensively on handle terminal equipments in wireless communication. The application of AMCs on PIFA can decrease longitudinal size or planar size of antenna, which is advantaged in actual application.
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