太赫茲波寬帶超材料吸收器的結(jié)構(gòu)設(shè)計(jì)與性能
發(fā)布時(shí)間：2018-11-21 19:56
【摘要】：超材料寬帶吸收器,尤其是結(jié)構(gòu)簡(jiǎn)單性能優(yōu)良的寬帶吸收器在電磁隱身,光電探測(cè)等方面都有極大的應(yīng)用前景,是太赫茲超材料領(lǐng)域的研究熱點(diǎn)。當(dāng)前,許多太赫茲超材料寬帶吸收器存在吸收帶寬有限、制作復(fù)雜、占空比較低等問(wèn)題,這在一定程度上限制了它的發(fā)展及應(yīng)用。通常,超材料寬帶吸收器的設(shè)計(jì)采用金屬-介質(zhì)多層交互疊加方式,或者周期內(nèi)排列組合多個(gè)圖形結(jié)構(gòu)的方式。在太赫茲波段,這些設(shè)計(jì)方法對(duì)微加工水平或超材料尺寸提出了很高的要求,因此難以大幅度提高吸收帶寬。本文通過(guò)對(duì)閉合金屬環(huán)諧振特性和電磁波帶寬疊加原理的研究表明,圖案層的閉合金屬環(huán)邊長(zhǎng)決定諧振峰的位置,不同金屬環(huán)產(chǎn)生的諧振峰相對(duì)獨(dú)立且相互影響較小,便于實(shí)現(xiàn)帶寬疊加。基于此特性,本文中設(shè)計(jì)平面同心嵌套金屬環(huán)結(jié)構(gòu)使一系列窄帶吸收峰在太赫茲波段相互疊加實(shí)現(xiàn)了寬帶吸收。對(duì)其吸收特性的研究表明,該器件為偏振無(wú)關(guān)器件,吸收帶寬為3.70THz,帶寬中心頻率比高達(dá)87.5%,對(duì)一定角度斜入射的TE、TM模式電磁波都能保持較高的吸收率,且吸收主要為金屬的歐姆損耗,并成功的利用了阻抗匹配原理和干涉理論對(duì)寬帶吸收進(jìn)行分析。平面嵌套結(jié)構(gòu)的超材料寬帶吸收器不僅具有制作簡(jiǎn)單、占空比高等優(yōu)點(diǎn),而且改變金屬線寬和金屬環(huán)間距可以提高超材料的吸收率,改變閉合環(huán)數(shù)量可以控制吸收帶寬。考慮到實(shí)際應(yīng)用中熱傳導(dǎo),熱電信號(hào)提取等問(wèn)題,基于同心嵌套金屬環(huán)圖形并結(jié)合天線結(jié)構(gòu)的設(shè)計(jì)思想,采用螺旋金屬線方式設(shè)計(jì)了吸收性能更為良好的太赫茲波寬帶吸收器。該吸收器為偏振不敏感器件,吸收帶寬高達(dá)5.26THz,在帶寬內(nèi)平均吸收率超過(guò)80%,帶寬中心頻率比接近90%。另外,利用天線結(jié)構(gòu)對(duì)電場(chǎng)的放大作用和超材料設(shè)計(jì)的可縮放性,在微波波段結(jié)合集總元素和螺旋天線結(jié)構(gòu)設(shè)計(jì)出了偏振無(wú)關(guān)的寬帶吸收器。
[Abstract]:Ultra-material broadband absorbers, especially broadband absorbers with simple structure and excellent performance, have great application prospects in electromagnetic stealth, photoelectric detection and so on, and are the research hotspot in the field of terahertz supermaterials. At present, many terahertz supermaterial broadband absorbers have some problems, such as limited absorption bandwidth, complex fabrication, low duty cycle and so on, which limits its development and application to a certain extent. In general, the ultra-material broadband absorber is designed by metal-dielectric multilayer interaction superposition, or by permutation and combination of multiple graphic structures within a period. In the terahertz band, these design methods require high level of micromachining or the size of supermaterial, so it is difficult to increase the absorption bandwidth greatly. In this paper, the resonant characteristics of closed metal ring and the superposition principle of electromagnetic wave bandwidth are studied. It is shown that the side length of the closed metal ring determines the position of the resonant peak, and the resonance peak produced by different metal rings is relatively independent and has little influence on each other. Easy to achieve bandwidth stacking. Based on this characteristic, a planar concentric nested metal ring is designed to achieve wideband absorption by superposing a series of narrowband absorption peaks at terahertz band. The results show that the device is polarization-independent, the absorption bandwidth is 3.70 THZ, the ratio of bandwidth to center frequency is as high as 87.5, and the absorption rate of TE,TM mode electromagnetic wave with oblique incidence at a certain angle can be kept high. The absorption is mainly the ohmic loss of metal, and the impedance matching principle and interference theory are used to analyze the wideband absorption successfully. The supermaterial broadband absorber with planar nesting structure not only has the advantages of simple fabrication and high duty cycle, but also can improve the absorptivity of the supermaterial by changing the metal wire width and the metal ring spacing, and the absorption bandwidth can be controlled by changing the number of closed rings. Considering the problems of heat conduction and thermoelectric signal extraction in practical applications, a terahertz wave wideband absorber with better absorption performance is designed based on concentric nested metal ring pattern and antenna structure design idea. The absorber is a polarization-insensitive device with a absorption bandwidth of up to 5.26THz. the average absorption rate is over 80 in the bandwidth, and the bandwidth central frequency ratio is close to 90. In addition, a polarization-independent wideband absorber is designed by combining lumped elements and helical antenna structures in microwave band, taking advantage of the amplification effect of antenna structure on electric field and the scalability of metamaterial design.
【學(xué)位授予單位】：華中科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：O441.4
[Abstract]:Ultra-material broadband absorbers, especially broadband absorbers with simple structure and excellent performance, have great application prospects in electromagnetic stealth, photoelectric detection and so on, and are the research hotspot in the field of terahertz supermaterials. At present, many terahertz supermaterial broadband absorbers have some problems, such as limited absorption bandwidth, complex fabrication, low duty cycle and so on, which limits its development and application to a certain extent. In general, the ultra-material broadband absorber is designed by metal-dielectric multilayer interaction superposition, or by permutation and combination of multiple graphic structures within a period. In the terahertz band, these design methods require high level of micromachining or the size of supermaterial, so it is difficult to increase the absorption bandwidth greatly. In this paper, the resonant characteristics of closed metal ring and the superposition principle of electromagnetic wave bandwidth are studied. It is shown that the side length of the closed metal ring determines the position of the resonant peak, and the resonance peak produced by different metal rings is relatively independent and has little influence on each other. Easy to achieve bandwidth stacking. Based on this characteristic, a planar concentric nested metal ring is designed to achieve wideband absorption by superposing a series of narrowband absorption peaks at terahertz band. The results show that the device is polarization-independent, the absorption bandwidth is 3.70 THZ, the ratio of bandwidth to center frequency is as high as 87.5, and the absorption rate of TE,TM mode electromagnetic wave with oblique incidence at a certain angle can be kept high. The absorption is mainly the ohmic loss of metal, and the impedance matching principle and interference theory are used to analyze the wideband absorption successfully. The supermaterial broadband absorber with planar nesting structure not only has the advantages of simple fabrication and high duty cycle, but also can improve the absorptivity of the supermaterial by changing the metal wire width and the metal ring spacing, and the absorption bandwidth can be controlled by changing the number of closed rings. Considering the problems of heat conduction and thermoelectric signal extraction in practical applications, a terahertz wave wideband absorber with better absorption performance is designed based on concentric nested metal ring pattern and antenna structure design idea. The absorber is a polarization-insensitive device with a absorption bandwidth of up to 5.26THz. the average absorption rate is over 80 in the bandwidth, and the bandwidth central frequency ratio is close to 90. In addition, a polarization-independent wideband absorber is designed by combining lumped elements and helical antenna structures in microwave band, taking advantage of the amplification effect of antenna structure on electric field and the scalability of metamaterial design.
【學(xué)位授予單位】：華中科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：O441.4
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