本文選題：超材料 + 超表面　； 參考：《東南大學(xué)》2016年博士論文

【摘要】：超材料由周期或非周期排布的亞波長的人工單元構(gòu)成,具有超常的電磁特性。因其可實現(xiàn)對電磁波的任意調(diào)控,因而受到了越來越廣泛的關(guān)注,涌現(xiàn)出一大批基于超材料研發(fā)的功能器件。超材料透鏡和超表面是超材料的兩種典型實現(xiàn)形式。其中超材料透鏡是由較多人工單元構(gòu)成的三維結(jié)構(gòu),當(dāng)電磁波在其中傳播時受到超材料的調(diào)控。而超材料的二維形式稱為超表面,其具有低剖面、低損耗、易于設(shè)計與實現(xiàn)等優(yōu)點,越來越受到研究者的關(guān)注。本文研究超材料透鏡和超表面對電磁波的調(diào)控及其應(yīng)用,主要內(nèi)容和創(chuàng)新點如下：·利用漸變折射率超材料透鏡在寬頻帶范圍內(nèi)實現(xiàn)對口面場幅度和相位的同時調(diào)控。通過控制漸變折射率透鏡的折射率分布,利用射線追蹤原理計算超材料透鏡內(nèi)部和透鏡出射面的射線分布,根據(jù)能量守恒原理計算出口面場的幅度分布、路徑積分計算射線光程獲得透鏡口面相位分布。通過優(yōu)化折射率分布,從而實現(xiàn)透鏡表面特定的幅度和相位分布。加工和測試了一工作于整個Ku波段的基于超材料的高增益低副瓣透鏡天線,在整個Ku頻段內(nèi)增益高于25.3dBi、副瓣電平均低于-26dB,達到了設(shè)計指標(biāo),證明了利用漸變折射率超材料透鏡調(diào)控口面場幅相的有效性。·通過喇叭內(nèi)部加載超材料透鏡實現(xiàn)角錐喇叭天線的旁瓣抑制。角錐喇叭天線口面幅度分布為準(zhǔn)TE10模式,其幅度近似均勻分布而相位為準(zhǔn)球面波分布的特點導(dǎo)致其E面旁瓣較高。在喇叭內(nèi)部通過加載超材料透鏡可將口面場振幅分布調(diào)控為錐削分布、相位調(diào)控為平坦分布,從而實現(xiàn)其旁瓣電平抑制。試驗中,在喇叭天線內(nèi)部加載一漸變折射率超材料透鏡,在不增加天線體積情況下實現(xiàn)了寬帶低旁瓣喇叭天線。·利用超材料透鏡將饋源輻射的球面波轉(zhuǎn)化為錐面波,實現(xiàn)了寬帶貝塞爾波束。設(shè)計超材料透鏡的折射率分布,從而實現(xiàn)將饋源發(fā)射的球面波直接轉(zhuǎn)化為錐面波,該錐面波束在距離透鏡出射面一定距離的空間區(qū)域形成截斷貝塞爾波束。該貝塞爾波束透鏡具有工作頻帶寬、轉(zhuǎn)換效率高、傳播距離遠(yuǎn)等優(yōu)點�！ぬ岢鼍幋a超材料、數(shù)字超材料和可編程超材料的概念。編碼超材料不同于傳統(tǒng)的“模擬”超材料的周期排布或漸變非周期排布,由若干種單元按照編碼的方式排布,不同的編碼具有不同的電磁響應(yīng)。一比特編碼超材料由兩種反射相位相差180度的人工單元構(gòu)成(稱為“0”單元和“l(fā)”單元),兩比特編碼超材料由四種反射相位相差90度的人工單元構(gòu)成(分別稱為“00”單元,“01”單元,“10”單元和“11”單元)。創(chuàng)新性提出了一種超材料單元,該單元由偏置二極管控制,實現(xiàn)“0”單元和“1”單元的狀態(tài)切換�；谶@一單元,設(shè)計了數(shù)字超表面,其每個單元可以是“0”單元態(tài)或“1”單元態(tài)。數(shù)字超材料是在編碼超材料的基礎(chǔ)上引入數(shù)字控制，，每個單元的特性是數(shù)字可控的。在此基礎(chǔ)上采用可編程邏輯陣列對各個單元的狀態(tài)實現(xiàn)現(xiàn)場編程控制,從而實現(xiàn)可編程超材料。數(shù)值仿真和初步實驗證實了上述概念和物理現(xiàn)象。·利用編碼超表面實現(xiàn)了微波和太赫茲波的異常反射。編碼超表面通過編碼對入射電磁波產(chǎn)生了不同于常規(guī)的異常反射。通過超表面一比特編碼實現(xiàn)多種異常反射：多波束反射、寬波束反射以及雙波束掃描反射等。在此基礎(chǔ)上,通過沿超表面兩個方向單獨編碼后組合,實現(xiàn)了多種異常反射組合的多樣反射現(xiàn)象。通過對超表面每一塊單元二維單獨編碼,實現(xiàn)了更靈活的反射波束的調(diào)控。不僅實現(xiàn)了微波段編碼超表面的異常反射,而且將頻段拓展至太赫茲,利用二維編碼超表面實現(xiàn)了太赫茲波的多波束反射。
[Abstract]:Supermaterials are composed of sub wavelengths of periodic or non periodic arrangement of subwavelengths, and have supernormal electromagnetic properties. Because they can realize the arbitrary regulation of electromagnetic waves, they are becoming more and more widely concerned. A large number of functional devices based on supermaterials are emerging. Supermaterial transmissions and supersurfaces are two typical forms of supermaterials. The supermaterial lens is a three-dimensional structure consisting of more artificial elements. When electromagnetic waves propagate in it, the supermaterial is regulated by supermaterials. The two-dimensional form of the supermaterial is called Supersurface, which has the advantages of low profile, low loss, easy to design and realize, and is becoming more and more concerned by the researchers. This paper studies supermaterial lens and supermeter. In the face of the control and application of electromagnetic wave, the main contents and innovations are as follows:. Using the gradient refractive index supermaterial lens to control the amplitude and phase of the opposite field in the wide band range. By controlling the refractive index distribution of the graded index lens, the internal and lens ejection surfaces of the supermaterial lens are calculated by ray tracing. According to the energy conservation principle, the amplitude distribution of the exit surface field is calculated. The path integral calculates the ray path to obtain the phase distribution of the lens mouth surface. By optimizing the refractive index distribution, the specific amplitude and phase distribution of the lens surface are realized. A high gain and low pair based on the supermaterial, working in the whole Ku band, is processed and tested. The petal lens antenna has a gain of higher than 25.3dBi in the whole Ku frequency band and an average of lower sidelobe electricity below -26dB. The design index is achieved. It is proved that the effectiveness of using the graded index supermaterial lens to control the field phase of the mouth field is proved. The side lobe suppression of the corner cone horn is realized by loading the supermaterial lens inside the horn. In the quasi TE10 mode, the amplitude is approximately uniform and the phase is the distribution of the paraspheric wave, which leads to the higher sidelobe of the E surface. The amplitude distribution of the mouth field can be controlled into a conical distribution through the loading of the supermaterial lens inside the horn, and the phase control is flat and thus the side lobe level is suppressed. A wide-band low sidelobe horn antenna is realized without increasing the volume of the antenna. Using a supermaterial lens, the spherical wave of the feed radiation is converted into a conical wave, and the broadband Bessel beam is realized. The refractive index distribution of the supermaterial lens is designed to achieve the direct transformation of the spherical wave transmitted by the feed. A truncated Bessel beam is formed in a space area with a certain distance from the ejection surface of the lens. The Bessel beam lens has the advantages of wide bandwidth, high conversion efficiency and long propagation distance. The concept of coding supermaterial, digital supermaterial and programmable supermaterial is proposed. The coded supermaterial is different from the traditional one. The periodic arrangement or gradual non periodic arrangement of the "analog" supermaterial is arranged by a number of units in a coded manner. Different codes have different electromagnetic responses. One bit coded supermaterial is composed of two artificial units (called "0" and "L"), and two bit coded supermaterials by four kinds. An artificial unit consisting of 90 degrees reflected phase difference (called "00" unit, "01" unit, "10" unit and "11" unit). A supermaterial unit is innovatively proposed. The unit is controlled by a bias diode to realize the state cutting of the "0" unit and the "1" unit. Based on this unit, a digital Supersurface is designed, each of which is designed. The unit can be a "0" element state or a "1" element state. Digital supermaterial is the introduction of digital control on the basis of the coded supermaterial. The characteristics of each unit are digitally controlled. On this basis, the programmable logic array is used to realize the programming control of the state of each unit, so as to realize the programmable supermaterial. Numerical simulation and initial. The step experiment confirms the above concepts and physical phenomena. The abnormal reflection of microwave and terahertz waves is realized by using the coded super surface. The coded super surface produces different anomalous reflections of the incident electromagnetic wave by coding. A variety of abnormal reflections are realized by the super surface one bit coding: multi beam reflection, wide beam reflection and double. Beam scanning reflection and so on. On this basis, a variety of abnormal reflection combinations are realized by combining the two directions of the super surface separately. By encoding each unit of the super surface individually, a more flexible reflection beam is realized. The abnormal reflection of the microwave segment coded super surface is not only realized. The frequency band is extended to terahertz, and the multi beam reflection of terahertz wave is realized by two dimensional coded super surface.
【學(xué)位授予單位】：東南大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2016
【分類號】：O441.4;TB34

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