本文選題：漏泄矩形波導(dǎo)　切入點(diǎn)：不連續(xù)結(jié)構(gòu)　出處：《北京交通大學(xué)》2017年碩士論文

【摘要】：隨著通信技術(shù)的發(fā)展和應(yīng)用需求的不斷提高,對受限空間和狹長區(qū)域的無線通信質(zhì)量也提出了更高的要求,如地鐵、隧道、礦井、以及高鐵和輕軌沿線等環(huán)境都要求提供穩(wěn)定可靠的無線通信,因此對這類場合中的電波覆蓋也相應(yīng)提出了更高的要求。然而,由于受限空間中電波多徑衰落影響大,狹長空間中電波容易干擾周邊或受周邊干擾,使用分立式天線系統(tǒng)通常無法達(dá)到滿意效果,因此在這類受限空間中通常采用漏泄同軸電纜或者漏泄波導(dǎo)來實(shí)現(xiàn)電波的高效覆蓋。然而,漏泄波導(dǎo)的實(shí)際應(yīng)用中也存在多種影響其輻射特性的因素,如各種不連續(xù)結(jié)構(gòu)或環(huán)境都會影響到其周圍電場的分布,因此需要對各種不連續(xù)情況可能帶來的影響進(jìn)行研究。本文針對這類應(yīng)用需求,重點(diǎn)研究波導(dǎo)之間法蘭盤、環(huán)境積雪以及中繼放大器前后功率差對漏泄波導(dǎo)產(chǎn)生的電波覆蓋的影響,為受限及狹長空間中基于漏泄波導(dǎo)的電波覆蓋系統(tǒng)的設(shè)計(jì)和評估提供重要依據(jù)。本文的主要工作和研究成果如下:1.研究了漏泄波導(dǎo)通過法蘭盤連接時造成的結(jié)構(gòu)上的這種不連續(xù)及其周圍電場分布的影響,同時還研究了法蘭盤位置偏離左右縫隙對稱中心時,對近場分布的均勻性造成的影響。針對這類情況提出了改善措施,即通過降低法蘭盤的高度或者將法蘭盤上部以不同的角度削掉來減少法蘭盤對電磁波的遮擋,從而提高電場分布的穩(wěn)定性。2.通過經(jīng)驗(yàn)公式計(jì)算出含水量不同的雪在2.4GHz時的介電參數(shù),研究了積雪在漏泄波導(dǎo)上以不連續(xù)狀態(tài)隨機(jī)分布時,漏泄波導(dǎo)周圍場分布受到的影響,并且分別從場沿波導(dǎo)的周向分布和軸向分布兩種情況深入分析了雪對場分布的影響機(jī)理。在分析研究基礎(chǔ)上,提出了減弱積雪影響的改善措施,即在積雪與波導(dǎo)之間放置介質(zhì)層,以減弱雪對能量的直接吸收。3.根據(jù)磁流源等效原理和陣列天線陣元與陣因子的關(guān)系,推導(dǎo)出了適用于漏泄波導(dǎo)近場分布的理論計(jì)算公式,研究了當(dāng)漏泄波導(dǎo)中繼放大器功率突然放大不同倍數(shù)(100倍、500倍、1000倍)時對中繼器所在區(qū)域耦合損耗的影響,并從理論上分析了這種現(xiàn)象出現(xiàn)的原因。據(jù)此提出了改進(jìn)措施,即采用涂覆吸波材料的方法,對功率較強(qiáng)一邊在一定距離內(nèi)的能量進(jìn)行適當(dāng)抑制,從而實(shí)現(xiàn)了中繼器前后耦合損耗的平穩(wěn)過渡。
[Abstract]:With the development of communication technology and the continuous improvement of application demand, the wireless communication quality of restricted space and narrow area has also put forward higher requirements, such as subway, tunnel, mine, etc.As well as high-speed rail and light rail along the environment are required to provide stable and reliable wireless communications, so the radio coverage in such cases is also put forward higher requirements.However, due to the large influence of multipath fading in confined space, radio waves in long and narrow space are apt to interfere with or be affected by peripheral interference, so it is usually not possible to achieve satisfactory results by using discrete antenna systems.Therefore, leakage coaxial cables or leaky waveguides are usually used to cover radio waves efficiently in this kind of confined space.However, in the practical application of leaky waveguides, there are many factors that affect their radiation characteristics, such as various discontinuous structures or environments that affect the distribution of electric fields around them.Therefore, it is necessary to study the possible effects of various discontinuities.In this paper, the effects of flange between waveguides, environment snow and power difference before and after relay amplifier on the radio wave coverage of leaky waveguides are studied in order to meet the needs of this kind of applications.It provides an important basis for the design and evaluation of radio coverage systems based on leaky waveguides in restricted and narrow space.The main work and research results of this paper are as follows: 1.The discontinuity of the structure and the influence of the electric field distribution around the leaky waveguide when connected through the flange are studied. The influence of the flange position deviation from the left and right slot on the distribution uniformity of the near field is also studied.The improvement measures are put forward, that is, by reducing the height of the flange or cutting off the upper flange at different angles to reduce the shielding of electromagnetic wave by the flange, thus improving the stability of electric field distribution.The dielectric parameters of snow with different water content in 2.4GHz are calculated by empirical formula. The effect of random distribution of snow on leakage waveguide in discontinuous state is studied.The influence mechanism of snow on the field distribution is analyzed from the circumferential distribution and axial distribution of the field along the waveguide.On the basis of analysis and research, the improvement measures of reducing the influence of snow cover are put forward, that is, the dielectric layer is placed between the snow and the waveguide to weaken the direct absorption of energy by snow.Based on the equivalent principle of magnetic current source and the relationship between array antenna elements and array factors, a theoretical calculation formula suitable for the near-field distribution of leaky waveguide is derived.The influence of the leakage waveguide relay amplifier on the coupling loss in the repeater region is studied when the power of the relay amplifier suddenly amplifies by 100 times or 500 times (1 000 times), and the reason of this phenomenon is analyzed theoretically.Based on this, the improvement measures are put forward, that is, the energy of the stronger side within a certain distance can be restrained properly by using the method of coating the absorbing material, so as to realize the smooth transition of the coupling loss before and after the repeater.
【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】：TN814

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本文編號：1726391