發(fā)布時間：2018-09-08 16:42

【摘要】：受限空間環(huán)境中的電波覆蓋特性關(guān)系到受限空間中無線通信的可靠性,會直接影響其中載體運行及人員的安全。由于圓極化波具有抗多徑衰落、抗極化失配等特點,因而被認(rèn)為能夠提供比較均勻的電波覆蓋,并且已經(jīng)有工程實例將圓極化天線作為受限空間中的發(fā)射天線使用,如西班牙馬德里隧道。然而圓極化波在受限空間的覆蓋情況到底如何,并沒有明確的結(jié)論,因為受限空間邊界復(fù)雜,反射波的極化多變,目前有關(guān)受限空間中圓極化波傳播的研究成果還很少,因此有必要對受限空間中圓極化天線及其產(chǎn)生的電波覆蓋進行深入的研究。本文利用基于鏡像原理的射線追蹤法,對圓極化波在矩形硬邊界受限空間中的電波覆蓋特性進行研究,并據(jù)此提出了兩種類型的圓極化陣列天線。這兩種天線分別使用蝴蝶結(jié)型天線和交叉振子天線作為陣列單元,橫截面積小,可在風(fēng)阻較大的受限空間中使用。本文的主要貢獻有如下幾個方面:1.研究了基于鏡像原理的射線追蹤方法,并且將電波覆蓋的研究與天線具體特性相結(jié)合。研究了矩形硬受限空間中不同極化波的傳播規(guī)律,對比分析了不同極化波的傳播特性差別,發(fā)現(xiàn)圓極化波在矩形隧道中的覆蓋特性處于水平極化和垂直極化兩種情況之間,分析了圓極化波這一特性的成因。2.分析了單向端射和雙向端射的發(fā)射天線在受限空間中的電波覆蓋特性。根據(jù)能量均勻性和系統(tǒng)能效因子,研究了在長受限空間中通過改變天線縱向分布位置來實現(xiàn)電波覆蓋特性優(yōu)化的方法,對受限空間中天線分布的實際設(shè)計有指導(dǎo)意義。3.采用正交放置的蝴蝶結(jié)型天線為單元,設(shè)計了低風(fēng)阻圓極化陣列天線。此陣列天線工作在900 MHz,在兩端輻射旋向相同的圓極化波,可作為發(fā)射圓極化波的多天線系統(tǒng)的單元使用,具有結(jié)構(gòu)緊湊、安裝方便的優(yōu)點。4.采用交叉振子單元設(shè)計、并制作了單向輻射和雙向端射的交叉振子單元圓極化陣列天線,兩個陣列天線都工作在當(dāng)前鐵路通信系統(tǒng)正推廣使用的1.7 GHz頻段,可分別用于發(fā)射圓極化波的單天線或多天線系統(tǒng)。
[Abstract]:The radio coverage in restricted space environment is related to the reliability of wireless communication in restricted space, which will directly affect the carrier operation and the safety of personnel. Because circular polarization wave has the characteristics of anti-multipath fading and anti-polarization mismatch, it is considered to be able to provide uniform radio coverage, and has been used as a transmitting antenna in confined space by engineering examples. For example, Madrid Tunnel, Spain. However, there is no clear conclusion on the coverage of circular polarized waves in confined space. Because the boundary of restricted space is complex and the polarization of reflected waves is changeable, there are few researches on the propagation of circular polarized waves in confined space. Therefore, it is necessary to study circularly polarized antennas and their radio coverage in confined space. In this paper, the radio wave coverage characteristics of circularly polarized waves in rectangular hard boundary confined space are studied by means of ray tracing method based on mirror image principle, and two types of circularly polarized array antennas are proposed. The two kinds of antennas use bow antenna and cross dipole antenna as array elements respectively. The cross section area of these two antennas is small and can be used in the limited space with high wind resistance. The main contributions of this paper are as follows: 1. The ray-tracing method based on mirror image principle is studied, and the research of radio coverage is combined with the characteristics of antenna. The propagation law of different polarization waves in rectangular hard confined space is studied. The difference of propagation characteristics of different polarization waves is compared and analyzed. It is found that the coverage characteristics of circular polarization waves in rectangular tunnels are between horizontal and vertical polarization. The cause of formation of circular polarization wave is analyzed. The radio coverage characteristics of one-way and bidirectional end-emitting antennas in confined space are analyzed. According to the energy uniformity and system energy efficiency factor, the method of optimizing the radio coverage characteristics by changing the position of antenna longitudinal distribution in long confined space is studied, which is of guiding significance to the practical design of antenna distribution in restricted space. A circular polarization array antenna with low wind resistance is designed by using an orthogonal bow-tie antenna as a unit. The array antenna works at 900 MHz, and radiates the same circular polarization wave at both ends. It can be used as a unit of multi-antenna system that emits circular polarization wave. It has the advantages of compact structure and convenient installation. A circular polarization array antenna with unidirectional radiation and bidirectional end emission is designed and fabricated by using cross oscillator element. Both array antennas are working in the 1.7 GHz frequency band which is being popularized in railway communication system. Single antenna or multi-antenna system can be used to transmit circular polarization wave respectively.
【學(xué)位授予單位】：北京交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TN821.1

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本文編號：2231091