【摘要】：太赫茲電控掃描天線能靈活的控制波束方向,提升太赫茲應用系統(tǒng)的時效性和準確性,因此成為了太赫茲天線技術(shù)研究的熱點問題。目前,太赫茲電控掃描天線通常利用石墨烯和液晶作為電調(diào)介質(zhì)實現(xiàn)波束掃描,然而,受限于制備工藝,當前高純度的石墨烯難以大面積生產(chǎn),這限制了石墨烯在太赫茲天線技術(shù)中的推廣。在液晶電掃反射陣列天線中,由于饋源喇叭的遮擋效應,天線波束的掃描范圍也受到了較大影響。為了解決上述問題,本文利用液晶的電調(diào)特性,對傳輸陣列天線進行研究。首先設(shè)計了單層液晶移相單元,在340 GHz可以實現(xiàn)90°的移相量。其次,為了增大陣列單元移相量,設(shè)計了雙層液晶移相單元,單元在340 GHz實現(xiàn)了180°的移相量,且插入損耗始終保持在1 d B左右。最后,利用雙層液晶移相單元完成了1-bit數(shù)字化液晶電掃傳輸陣列天線的設(shè)計,波束掃描范圍達到了-40°~+40°。設(shè)計的液晶電掃傳輸陣列天線為太赫茲頻段內(nèi)電控掃描天線的設(shè)計提供了新的思路。此外,本文對液晶的介電特性也進行了深入研究,從液晶材料中射頻電場與靜電場矢量方向為切入點,提出了一種優(yōu)化液晶等效介電常數(shù)調(diào)諧范圍的方法:對液晶中射頻電場與靜電場矢量方向的角度差進行建模,并采用分權(quán)相加的思路來調(diào)和液晶層中各位置角度差與射頻電場的關(guān)系,進而判斷液晶調(diào)諧力度的大小,并通過對比仿真驗證了這種優(yōu)化方法的正確性。這種優(yōu)化方法對今后液晶調(diào)諧器件的設(shè)計具有一定的參考價值。
[Abstract]:THz scanning antenna can flexibly control the direction of the beam, improve the timeliness and accuracy of THz application system, so it has become a hot issue in the research of THz antenna technology. At present, terahertz electronic controlled scanning antenna usually uses graphene and liquid crystal as electrically modulated medium to realize beam scanning. However, limited by the preparation process, it is difficult to produce high purity graphene in large area. This limits the spread of graphene in terahertz antenna technology. The scanning range of the antenna beam is also greatly affected by the shielding effect of the feed horn in the liquid crystal electro-sweep array antenna. In order to solve the above problems, the transmission array antenna is studied by using the electromodulation characteristics of liquid crystal. First, a single-layer liquid crystal phase shifting unit is designed, which can realize 90 擄phase shift at 340 GHz. Secondly, in order to increase the phasor of array elements, a double-layer liquid crystal phase-shifting unit is designed. The phase shift of the cell is 180 擄at 340 GHz, and the insertion loss is always about 1 dB. Finally, the design of 1-bit digital LCD transmission array antenna is completed by using double-layer liquid crystal phase shifting unit. The beam scanning range is -40 擄~ 40 擄. The design of liquid crystal electro-sweep transmission array antenna provides a new idea for the design of electronic controlled scanning antenna in terahertz band. In addition, the dielectric properties of liquid crystal are also studied in this paper, starting from the direction of RF electric field and electrostatic field vector in liquid crystal material. A method for optimizing the tuning range of the equivalent dielectric constant of liquid crystal is proposed. The angular difference between the radiofrequency electric field and the vector direction of electrostatic field in liquid crystal is modeled. The relationship between the position angle difference and the RF electric field in the liquid crystal layer is adjusted by using the idea of separation of power and addition, and the magnitude of the tuning force of the liquid crystal is judged, and the correctness of the optimization method is verified by comparison and simulation. This optimization method has certain reference value for the design of liquid crystal tuner in the future.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TN820.15

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