Dissertation abstract: Study on fabrication for broadband perfect absorption in the Ghz region based on metamaterials

The thesis focuses on studying MA operating in the frequency region of 2-18 GHz in 2 main approaches: Asymmetric and isotropic MA with multi-peak; broadening the absorption range by integrating conductive polymer; the content of the thesis is based on a consistent combination of theoretical models and simulation software.
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Dissertation abstract: Study on fabrication for broadband perfect absorption in the Ghz region based on metamaterials0MINISTRY OF EDUCATION AND TRAINING VIETNAM ACADEMY OF SCIENCE AND TECHNOLOGY GRADUATE UNIVERSITY OF SCIENCE AND TECHNOLOGY Đinh Hồng Tiệp STUDY ON FABRICATION FOR BROADBAND PERFECT ABSORPTION IN THE GHz REGION BASED ON METAMATERIALS MAJOR: ELECTRONIC MATERIAL NUMBER: 62.44.01.23 DISSERTATION ABSTRACT Hanoi - 2020 1This thesis was accomplished in: Graduated University of Science and Technology – VietnamAcademy of Science and TechnologySupervisor: Prof. Dr. Vũ Đình LãmPeer reviewer 1:Peer reviewer 2:Peer reviewer 3:This thesis will be defended inThe dissertation will be defended in front of the Institute of Doctoral Dissertation Assessment Council,taking place at the Academy of Science and Technology - Vietnam Academy of Science and Technologyat ... hour .... , day ... month ... year 201 ....This thesis will be stored in:- Library of Graduated University of Science and Technology- Vietnam National Library 2 PROLOGUE1. Necessaries of thesis In recent years, advanced materials have played an important role in developing modern technologiesto satisfy the emerging needs of people. Technology innovation always goes along with the integration ofnoble materials existing in nature, or new advanced materials with artificial structures containingunprecedented properties. This motivation led to the creation of metamaterials (MMs) - artificial structure withelectromagnetic characteristics that can not be found in. Over more than two decades from Veselagos modelof theoretical prediction in 1968, MMs raised a revolution in advanced materials, as well as posed manychallenges to basic sciences. It is possible to change the conventional rules of interaction between matter andelectromagnetic waves, such as bending light path, the inversion of the transmission of electromagnetic wavesto the energy flow or the reverse Cherenkov radiation. These peculiar and interesting characteristics haveopened up a promising prospect for material science to gradually realize expectations that exist only in thehuman sci-fi world. In particular, the perfect absorption of electromagnetic waves in MMs was demonstrated for the firsttime by Landy and colleagues in 2008 that stirred the researching area of stealth materials. This new generationof absorbing materials is much smaller in size than the traditional one. Therefore, the new field of research,called the Metamaterial Perfect Absorbers (MPAs), has been developed rapidly in both theory and experiment.MPAs show advantages when their physical thickness is much smaller than operating wavelengths (which canbe thousands of times smaller), while traditional absorbing materials have a thickness limitation of λ/4. Witha size of λ/30, the metamaterial absorber proposed by Landys team recorded absorption of 88% at 11.5 GHzin experiment, while this value was up to 96% at 11.48 GHz in simulation. With such outstanding properties,MPAs are also rapidly being studied extensively for practical applications from the MHz region to the opticalregion. However, the fundamental mechanism of MMs is strongly dependent on the structure of resonators,then, the operating frequency range is very narrow. This is the main cause of the lack of MMs with a simplestructure, low cost of manufacture that can operate in multiple bands or in a wide frequency rangesimultaneously. In addition, maintaining multiple absorptions or absorption peaks on a wide range alwaysrequires increasing the unit cell dimensions or the physical thickness of symmetrical structures. In particular,constituent materials used in the fabrication of metamaterial absorber (MA) (metal-dielectric) are ofteninelastic, leading difficulties to cover it on curved surfaces of objects in practice. Therefore, it is still achallenge to uphold studying more advanced features for micro-structure MMs, with multi-band and widebandoperation using recent manufacturing. 2. Purposes of the thesis - Building up a theoretical basis, studying MA operating in multi-band and broadband in the frequencyregion of 2-18 GHz. - Designing and optimizing structural parameters of MA operating in multi-band and broadband basedon new models. Researching on MA operating in multi-band and broadband with simple structure andindependent to the polarization of incident electromagnetic waves. - Elaborating and applying asymmetry in the geometrical structure of MMs to create multi-ba ...