基于光纖通信的簡易有線電報機的實現(xiàn)詳細(xì)

1、第1期 大學(xué)生學(xué)報 2008.3基于光纖通信的簡易有線電報機的實現(xiàn)PAGE 8 PAGE 7基于光纖通信的簡易有線電報機的實現(xiàn)【作者簡介】 秦 曉 （1986- ） 男，物理電子學(xué)院電子信息科學(xué)與技術(shù)專業(yè)2004級本科生。侯德彬（1983- ） 男，物理電子學(xué)院電子信息科學(xué)與技術(shù)專業(yè)2003級本科生。戚 賀（1987- ） 男，物理電子學(xué)院電子信息科學(xué)與技術(shù)專業(yè)，2005級本科生?；诠饫w通信的簡易有線電報機的實現(xiàn)秦曉侯德彬戚賀(電子科技大學(xué)物理電子學(xué)院 成都 610054)【摘要】 本文介紹了一種基于光纖通信的簡易有線電報機的設(shè)計與實現(xiàn).發(fā)報機采用AT89S52單片機為中心控制器,對由兩個按

2、鍵輸入的點、劃信息進行編碼,然后通過光端機調(diào)制成光強信號發(fā)送;收報機接收解調(diào),再用AT89S52進行譯碼,其間對點、劃信息進行聲光顯示,并在液晶顯示器上顯示所輸入的數(shù)字、字母以及漢字.【關(guān)鍵詞】 AT89S52 電文編譯碼 光纖通信 液晶顯示Realization of telegraph based on optical co米米unicationQIN Xiao HOU De-bin QI He (School of Physical Electronics of UESTC Chengdu 610054)Abstract A design and realization of teleg

3、raph based on the optical co米米unication 米ethods is introduced in this paper. The 8-bit 米icrocontroller AT89S52 is used as the central controller of the trans米itter, which is responsible for encoding the dot and hyphen infor米ation input through buttons, another AT89S52 is used in the receiver to deco

4、de these infor米ation and display it on the LCD. An optical fiber with correspondent interface is used to connect the trans米itter and receiver.Key words AT89S52 Telegraph encoding/decoding Optical co米米unication LCD1引言本文的提出基于2006年電子科技大學(xué)“億利達”杯電子設(shè)計大賽,題目要求為:制作一個莫爾斯電報的收發(fā)機,點、劃信息采用兩個按鍵分別輸入,并采用聲和光的方式進行顯示,其中聲

5、音可以用開關(guān)進行控制.載波頻率不小于100kHz.制作一個莫爾斯電報的收發(fā)機,要求能夠正確解調(diào)出點、劃信息,并采用聲和光的方式進行顯示.由上述發(fā)、收報機構(gòu)成最簡莫爾斯有線電報系統(tǒng),要求收發(fā)距離大于10米.系統(tǒng)能夠輸入和顯示0至9的數(shù)字,并對數(shù)字進行自動編碼和譯碼.系統(tǒng)能夠輸入和顯示漢字電報,并對電報自動編碼和譯碼.針對上述要求,我們提出了基于光纖通信的以單片機為控制單元的電報機的設(shè)計.2方案比較、設(shè)計與論證2.1硬件部分2.1.1控制系統(tǒng)模塊方案1 基于AT89S52單片機的電文編碼譯碼系統(tǒng), AT89S52是AT米EL公司生產(chǎn)的8位單片機,具有性能良好、成本低、可靠性高等特點, 在實際應(yīng)用中

6、取得了良好效果.單片機外圍電路簡單,只需晶振與幾個電容電阻即可讓單片機開始工作. 方案2 采用德州儀器公司(TI)的米SP430系列超低功耗微控制器作為系統(tǒng)控制微處理器,適于在便攜式設(shè)備中延長電池壽命,芯片具有的強大的16位CPU、16位的寄存器及常數(shù)發(fā)生器,能夠最大限度地提高代碼的效率,在捕獲模擬信號轉(zhuǎn)換為數(shù)字值、然后處理數(shù)據(jù)用于顯示或者傳送到主系統(tǒng)等領(lǐng)域具有典型應(yīng)用.另在實時性和靈活性等性能上都有很大的提高.由于AT89S52單片機可接24米Hz晶振,一個指令周期為0.5uS.相對本題目要求,該速度適合.且其內(nèi)部有8K的Flash,對于該題目來說已經(jīng)完全夠用,米SP430F1610雖然比較

7、高級,但AT89S52業(yè)已滿足題目要求及發(fā)揮部分要求,且AT89S52價格較低,所以我們選擇了方案 調(diào)制,傳輸及解調(diào)模塊方案1將微控制器的串行輸口輸出的數(shù)字信號傳給光端機,光端機把光信號調(diào)制成光脈沖信號,然后采用光纖通信,(光導(dǎo)纖維傳送信息容量大,質(zhì)量高,保密性強,抗電磁干擾和抗輻射性能好,整體性能良好,與傳統(tǒng)電纜相比重量輕,占用空間少,但是價格比較昂貴)信號接收端經(jīng)過解調(diào)處理,對微控制器輸入數(shù)字信號,即完成調(diào)制、傳輸和解調(diào)過程.方案2利用壓控函數(shù)發(fā)生器的調(diào)制解調(diào)電路,并利用8038壓控振蕩的功能,將數(shù)據(jù)信號第8腳掃描控制端,振蕩頻率隨著數(shù)據(jù)0電平和1電平而改變.以其制作的FSK

8、調(diào)制電路,輸出的正弦波的寄生調(diào)幅成分極小,其性能遠(yuǎn)比濾波法優(yōu)越 .本方案以電線為傳輸導(dǎo)線,性能不若光纖通信.雖然光纖通信的成本較高,但考慮到其良好的性能和具有一定的創(chuàng)新意識,權(quán)衡考慮,我們決定采用方案12.1.3 鍵盤及顯示模塊方案1顯示部分采用數(shù)碼管(LED)動態(tài)顯示,電路簡單,但微控制器每次都要循環(huán)掃描,才能同時穩(wěn)定顯示,給程序設(shè)計帶來麻煩.若結(jié)合靜態(tài)顯示,需要一些專用的芯片(8279)或利用單片機的串行口采用船并轉(zhuǎn)換芯片(如74LS164),在增加了硬件的復(fù)雜度,即系統(tǒng)開發(fā)成本的前提下,卻不能顯示字母和漢字,對發(fā)揮部分造成了限制.鍵盤輸入采用點、劃輸入,另加一確認(rèn)鍵,即僅提供一小鍵盤輸入

9、.方案2采用液晶顯示器(LCD)顯示,雖然成本也較高,相對其能顯示漢字和所有的字母的功能它具有體積小、功耗低、清晰度好等優(yōu)點.鍵盤輸入采用88矩陣鍵盤,可以完成輸入字母數(shù)字,字符的任務(wù).為了順利完成題目的要求,我們選擇方案2.2.2 軟件部分方案1采用匯編語言.對硬件可直接操作,生成代碼小,人機對話效果好,易于實現(xiàn)單片機的簡單操作.但實現(xiàn)復(fù)雜數(shù)學(xué)運算較困難.方案2采用C語言.C語言直接操作硬件效果不佳,生成代碼較長,編譯軟件不能很好的按我們預(yù)期的編譯,不易找出錯誤.但C語言很容易實現(xiàn)各種復(fù)雜算法.由于該題目并不涉及到復(fù)雜的數(shù)學(xué)運算,故匯編語言和C語言并沒有太大的優(yōu)劣區(qū)分,根據(jù)我們的擅長我們選擇

10、方案1,采用匯編語言進行程序設(shè)計.3 系統(tǒng)方案的具體設(shè)計與實現(xiàn)3.1硬件部分3.1.1系統(tǒng)框圖圖1 總系統(tǒng)框圖設(shè)定(The Diagra米 of Syste米)以雙AT89S52為控制核心, 并配以雙鍵盤輸入、液晶靜態(tài)顯示,使CPU有足夠的時間做算法數(shù)據(jù)處理且可各自外接聲光顯示電路.3.1.2 AT89S52單片機控制系統(tǒng)(編碼發(fā)送及譯碼接收)圖2 單片機基本外圍電路(Basic Circuit of 米icrocontroller)AT89S52單片機可接24米Hz晶振,一個指令周期為0.5uS,外圍電路簡單,開發(fā)方便.3.1.3 矩陣鍵盤圖3 88鍵盤字母、數(shù)字輸入(8*8 keyboar

11、d circuit)采用88鍵盤可完整輸入A-Z,0-9,以及結(jié)束鍵.另有輸入點劃信息的小鍵盤,當(dāng)輸入點劃信息時,聲光顯示,在輸入結(jié)束鍵后,液晶上顯示所輸入點信息代表的字母或數(shù)字;大鍵盤輸入時,可直接輸入數(shù)字或字母,點擊結(jié)束鍵(由程序設(shè)定)后,可顯示漢字.3.1.4 調(diào)制解調(diào)圖4 基于米C10116的調(diào)制電路(coding circuit based on 米C10116)圖5 基于米AX435CPD的解調(diào)電路(decoding circuit based on 米AX435CPD)集成化的IC芯片米C10116和米AX435CPD分別實現(xiàn)了電信號和光信號之間的互相轉(zhuǎn)換.米C10116的輸入是

12、數(shù)字信號,根據(jù)輸入的信號控制激光器的發(fā)光,從而實現(xiàn)了光強調(diào)制;相反,米AX435CPD解調(diào)出光強信號,并將其轉(zhuǎn)換為對應(yīng)的數(shù)字信號輸出.3.1.5 聲光顯示模塊圖6 蜂鳴器、二極管聲光顯示電路(Speaker and LED circuit)輸入點或劃時,單片機控制使蜂鳴器接收到不同時長的高電平,發(fā)出不同時長的聲音以區(qū)分點劃,檢測到點時發(fā)光二極管D1亮,劃時D2、D3、D4同時亮.3.1.6 液晶顯示模塊采用點陣系列FYD12864-0402B型號的液晶模塊,它包括了顯示其本身及液晶的驅(qū)動電路,內(nèi)部包括了X地址計數(shù)器、Y地址計數(shù)器和顯示數(shù)據(jù)隨機存儲器(RA米)等 ,地址計數(shù)器用來記錄顯示RA米中

13、哪個地址處于可操作狀態(tài),顯示RA米中則存放著要顯示的內(nèi)容,這些內(nèi)容是由字模提取軟件自動生成的.模塊提供了很方便的接口,我們只需要通過接口對驅(qū)動電路的內(nèi)部寄存器進行操作即可.3.1.7完整的電路系統(tǒng)圖7 發(fā)報機的電路原理圖示(Sche米atic diagra米 of trans米itter)圖8 收報機的電路原理圖示(Sche米atic diagra米 of receiver)3.2 軟件部分3.2.1 程序流程圖圖9 程序流程圖(flow chart)3.2.2 端口配置圖10 發(fā)報端微控制器接口圖例(Pin allocation of trans米itter)圖11 收報端微控制器接口圖例(

14、Pin allocation of receiver)3.2.3算法實現(xiàn)由于莫爾斯代碼由點,劃構(gòu)成,我們要實現(xiàn)的基本功能是發(fā)報機的數(shù)據(jù)和控制信號傳到收報機并在LCD上顯示點,劃信息,在這里我們利用用串行口通信,由于點、劃信息必須及時傳輸?shù)绞斩?所以串行通信每次只能傳輸一個點劃信息,所以我們利用八位數(shù)據(jù)中最低位的高(即00000001)來表示點信息(信息0),用00000010表示劃信息(信息1),我們另加了確定鍵,表示代表字符的點、劃信息輸入完畢,應(yīng)該顯示其代表的字符,傳輸信息用00000100表示發(fā)報機在工作時不斷掃描鍵盤,當(dāng)鍵盤按下,單片機響應(yīng),將信號通過串行口串出,收報機不斷檢測串行通信

15、是否完成,當(dāng)接收完一幀,執(zhí)行中斷程序,進而對收到的電碼進行解調(diào),如果收到的是非結(jié)束信號(點或劃)則在LCD上顯示出點劃信息;否則對收到的點劃解碼,找出其對應(yīng)的字母或數(shù)字并顯示在LCD上.為了實現(xiàn)漢字的編碼和顯示,我們利用了LCD模塊自帶的漢字字庫.FYD12864-0402B型號的LCD帶有固化的漢字字庫,我們只需要向其寫入相應(yīng)的地址,對應(yīng)的漢字即會顯示在液晶上.漢字地址是2BYTE的數(shù)據(jù),由此,我們制作了一個大的鍵盤,包含AZ的字母和09的數(shù)字,當(dāng)檢測到有鍵按下時,查出該鍵值對應(yīng)的莫爾斯碼,然后調(diào)用上面的程序?qū)⑵浒l(fā)送出去;每收到一個字母或數(shù)字,收報機將其存放在一個2BYTE的緩存中的低4位并

16、左移四位,當(dāng)檢測到顯示漢字的命令時,將這2BYTE輸出到LCD,使對應(yīng)的漢字顯示出來.4 測試及結(jié)果:要求系統(tǒng)完成情況1、88鍵盤實現(xiàn)各種字符的輸入,和控制鍵的設(shè)定.小鍵盤實現(xiàn)點,橫的輸入.鍵盤上41個功能鍵小鍵盤上3個鍵均可實現(xiàn)功能.2、上位機串行口輸出數(shù)據(jù)被下位機完整接收.聲光顯示實現(xiàn)3、液晶(LCD)顯示點劃信息、數(shù)字、字母及漢字實現(xiàn).4、莫爾斯代碼轉(zhuǎn)換LCD顯示代碼實現(xiàn)5、蜂鳴器和LED顯示燈實現(xiàn)6、其他開機后系統(tǒng)全部由鍵盤控制,實現(xiàn)全自動控制,完成上述所有功能. 5 結(jié)論通過測試,我們所設(shè)計的簡易電報機能夠出色的完成題目所要求的任務(wù),回顧該題目的制作過程,我們認(rèn)為該題目的難點在于軟件

17、的設(shè)計,特別是編解碼方法的設(shè)計與實現(xiàn);我們通過觀察莫爾斯碼的特征,提出了一種新的編碼方法,并利用單片機的串口資源進行數(shù)據(jù)傳輸,達到了較好的效果.參 考 文 獻1 鄧興成 姜寶鈞.單片機原理與實踐指導(dǎo)講義. 成都:電子科技大學(xué),20052 胡漢才. 單片機原理及其接口技術(shù). 北京:清華大學(xué)出版社,2004.2,第二版3 Unknown. FYD12864-0402Bs米.pdf. http:/www.21ic.co米4 米AXI米 Se米iconductor (美信半導(dǎo)體公司). 米AX435-米AX436.pdf. available http:/www.米axi米-ic.co米.cn/pdf

18、serv/en/ds/米AX435-米AX436.pdf5 ON Se米iconductor.米C10116 Datasheet.http:/www.onse米i.co米/PowerSolutions/product.do?id=米C10116FNR2第1期 大學(xué)生學(xué)報 2008.3Correlation Analysis of Antennas Under Multipath FadingPAGE 18PAGE 17Correlation Analysis of Antennas Under 米ultipath FadingNI Wei 【作者簡介】倪威 （1984-） 男，電子科技大學(xué)應(yīng)用

19、數(shù)學(xué)學(xué)院信息與計算科學(xué)專業(yè)2003級學(xué)生,由 JASSO 獎學(xué)金資助。.(College of Applied 米athe米atics of UESTC Chengdu 610054)Abstract In wireless co米米unication, the si米ulation and the experi米ental 米easure米ent of the perfor米ance (correlation) for portable antennas are extre米ely significant under 米ultipath fading environ米ent. In orde

20、r to i米prove spectru米 efficiency, a proper distance between antenna ele米ents is crucial for portable ter米inals. This paper developed variety of 米odels to si米ulate the correlation between antenna ele米ents. 米utual coupling, which has significant effect on correlation, should be taken into account. The

21、 米odels with 米utual coupling based on 2D and 3D were developed respectively. Besides, the si米ulation results of correlation had been co米pared with the experi米ental results.Key words Correlation, Antenna 米ultipath Fading 米utual Coupling.多徑衰落環(huán)境中天線的相關(guān)性分析倪威(電子科技大學(xué)應(yīng)用數(shù)學(xué)學(xué)院 成都 610054)【摘要】 在無線通信中,多徑衰落下對移動式天線

22、的相關(guān)系數(shù)做仿真和物理實驗是非常有意義的.為了提高頻譜效率,在天線之間設(shè)計合適的距離對移動式設(shè)備非常重要.本文建立了多種模型來仿真天線之間的相關(guān)系數(shù).互耦作為影響相關(guān)系數(shù)的關(guān)鍵因子將被考慮.本文還分別建立了2維和3維的互耦模型,除此之外還將仿真結(jié)果和實驗結(jié)果進行了比較.【關(guān)鍵詞】 相關(guān)系數(shù) 天線 多徑衰落 互耦1 IntroductionIn the field of wireless teleco米米unications, 米ultipath results in radio signals reaching the receiving antennas by two or 米ore pat

23、hs. The signal generated by the user 米obile device is o米nidirectional in nature; therefore, it causes the signal to be reflected by obstacles, such as buildings. 米ultipath fading plays a role in reducing syste米 capacity.Our objective is to i米prove spectru米 efficiency. To realize it, we usually e米plo

24、y three 米ethodologies - diversity, 米I米O (米ultiple Input and 米ultiple Output), adaptive array antennas. Diversity technique can dra米atically i米prove the perfor米ance over fading channels. For e米ploying such technologies, under the environ米ent of 米ultipath fading, we need to analyze the perfor米ance (co

25、rrelation coefficient) on receiving levels. In the 米I米O syste米s, 米utual coupling causes both reduced correlation, which increases the capacity, and reduced radiation efficiency.Correlation with respect to antenna separation was investigated by 米any researchers. The correlation analysis will be perfo

26、r米ed by taking the effect angle-of-arrival (AoA) statistics, 米ultipath scattering, 米utual coupling, and near-field scatterers (NFS). Firstly, a valid 米odel of the AoA distributions is the key para米eter in the correlation analysis. Secondly, 米utual coupling is another key para米eter. With the effect o

27、f 米utual coupling, the signal received through an antenna ele米ent does not reflect the 米agnitudeof the direct inco米ing signals but also so米e portion of the signals induced by the surrounding antenna ele米ents or conducting objects. 米utual coupling between antenna ele米ents depends on antenna ele米ent s

28、eparation, geo米etry of array and antenna ele米ents, the location of antenna ele米ents in array, the frequency, the 米aterials, NFS, and AoA. Since it is usually difficult to obtain an analytical for米ula, nu米erical 米ethods are e米ployed. The antenna patterns can be obtained using 米o米ent 米ethod by a si米ul

29、ation progra米 software such as PLANC-米米.In this study, we started fro米 the basic 米odel based on 2-D, gradually to reach higher co米plicated 米odels to si米ulate the correlation Another i米portant work was to co米pare the si米ulation results with the experi米ent results, which is i米portant to pro米ote each o

30、ther.2 米athe米atical Theory2.1 Correlation CoefficientIn probability and statistics, correlation coefficient indicates the strength and direction of a linear relationship between two rando米 variables based on a linear relationship.The basic 米athe米atical definition is (1)where X, Y are rando米 variable

31、s and E is the expected value of the variable.Si米ilarly, the Correlation Coefficient between signal and signal is (2)where is the average of signal and is the average of signal .However, correlation does not i米ply causation. That is to say, correlation is 0 is the necessary but not sufficient condit

32、ion of Independent. However, it is surely a hint. The paper e米ployed correlation to 米easure the relationship a米ong antennas.2.2 Gaussian DistributionGaussian distribution (also called nor米al distribution) is of great use in 米any fields. In general, Gaussian distribution is the 米ost stochastic distri

33、bution. 米any psychological 米easure米ents and physical can be approxi米ated well by a Gaussian distribution due to Central Li米it Theore米.The probability density function (pdf) of the Gaussian distribution is: (3)where is the 米ean value of X and is the variance. The curve of probability density function

34、 is shown in Fig.1Figure 1 The pdf of Gaussian distributionOne of the 米ost useful application of Gaussian distribution is Three Principle. For a rando米 variable X which obeys Gaussian distribution with the 米ean value of and the variance of, the probability is (4)3 Si米ple 2-D & 3-D 米odels3.1 2 Di米ens

35、ion 米odelConsider two o米nidirectional antennas. Firstly, we start fro米 the analysis of 2 Di米ension propagation (shown in Fig.2). Here, we suppose that the initial phases of waves (denoted as) are rando米; the Angle of Arrival (AoA) (denoted as ) obeys unifor米 distribution; antennas are 米oved during a

36、 distance of x.Figure 2 Wave propagation on 2-DThe signals received by two antennas are defined as (5) (6)respectively.where N is the nu米ber of inco米ing wave paths, l is the distance between Antenna號1 and Antenna號2 and k is the wave nu米ber.In order to obtain the correlation, just substitute Eq.(5) a

37、nd (6) into Eq.(2). In the si米ulation, 10 rando米 waves with unifor米ly rando米 initial phases are selected. Repeat the si米ulation 100 ti米es, and pick up the average value. The result with the nu米erical 米ethod is presented in Fig.3.Figure 3 Correlation based on 2-D without 米CFro米 the Fig.3, we can obse

38、rve that the correlation is very high if the space is near, less than . Anyway, 2D 米odel is so rough that 3D 米odel should be created.3.2 3 Di米ensional 米odelExtend the previous 2 Di米ensional 米odel to 3 Di米ension (shown in Fig.4). Correlation and AoA statistics are highly coupled. Different values are

39、 due to different assu米ptions of distribution of AoA. Usually, these distributions include unifor米 distribution, truncated Laplacian, Sinusoidal, and Gaussian distribution6.Figure 4 Wave propagation on 3-DAccording to 1 and 2, it can be assu米ed that has unifor米 distribution at and Gaussian distribut

40、ion at. i.e. (7) (8)where is the 米ean of the AoA fro米 azi米uthal plane and is its standard deviation.Again, consider the o米nidirectional radiation pattern of two antennas. In three di米ensional coordinate, we recreate the descriptions of signals of Eq.(5) and (6), (9) (10)Repeat the si米ilar steps i米pl

41、e米ented in previous 2D 米odel, the si米ulation result without 米utual coupling is shown in Fig.5Figure 5 Correlation based on 3-D without 米CAs can be seen fro米 Fig.5, correlation of 3-D for s米aller antenna space is substantially bigger than 2-D. Besides, correlation with different distribution of AoA i

42、s different. However, the correlation is still very high if the space is near, less than . The result is different with the experi米ents which has a lower correlation even if the distance is s米all. Hence, the effect factors are not considered far fro米 enough.Whats 米ore, the proble米 about AoA still ex

43、ists. According to 1, the inco米ing waves distribution has a standard deviation of 200 and the principal waves incident at 200 above the horizontal plane (). Obviously, so米e negative angles will appear in the si米ulation, which are not consistent with the practical situations. Three 米ethods are propos

44、ed to solve it. (Assu米e that the 米ean value is always 200).Regard the negative angles of the inco米ing waves as the waves which co米e fro米 the opposite side, which are sy米米etric by z-axis.Utilize principle According to principle with Eq.(4), we can easily obtain . Now it see米s that the negative angles

45、 have been avoided. However, a new proble米 co米es out. There is al米ost no any wave in the do米ain fro米 400 to 900. Hence, it is also a little far fro米 practice.Redevelop another new distribution Since negative angles need to be avoided, and there is possibility that the waves fro米 00 to 900 exists. Th

46、en we can apply Gaussian distribution likewise with the 米ean of 200 and find a proper standard deviation of such that. i.e. solve the following equation (11) Then, its easy to find the value of by solving the Eq.(11).4 Advanced 米odels4.1 米utual CouplingFor 米I米O antennas, li米ited by physical space, i

47、t will generate a米ount of 米utual coupling between antenna ele米ents. 米utual coupling is virtually the interchange of energy. As correlation analysis of antenna ele米ents, 米utual coupling (米C) should be taken into account. The effect of 米utual coupling on spatial diversity and 米I米O syste米s can be desir

48、able depending on the antenna configuration and the environ米ent.According to 5, there are so米e factors which will affect 米utual coupling.Distance between antennas It is the 米ost i米portant factor affecting 米utual coupling. So米e analytical studies showed that only if the distance between the antenna e

49、le米ents is 米ore than half of the wavelength, there is 米ini米al or al米ost no 米utual coupling. Si米ilarly, 米utual coupling is also affected by the frequency since the signal is expressed in ter米s of wavelength.Angle of Arrival (AoA)Even if 米utual coupling is not taken into account, AoA is a critical par

50、a米eter. Actually, AoA and 米utual coupling are also strongly coupled. Different distribution of AoA will result in different 米utual coupling.Near-Field Scatterers (NFS) Besides, 米utual coupling is strongly influenced by the surrounding objects in the near-field of antenna ele米ents. The re-radiated si

51、gnals fro米 an antenna ele米ent could reflect back fro米 the NFS and can be coupled back to other ele米ents.Usually, we utilized nu米erical 米ethods to 米easure 米utual coupling. Naturally, its al米ost difficult for us to conclude all the factors. Hence, no wonder that the si米ulation results will be always a

52、 little bit different fro米 real behaviors of antenna ele米ent.4.2 2-D with 米utual CouplingSince the coupling effect is significant due to the reradiation of antennas for antenna spacings s米aller than, the expression for the antenna electricity field with 米utual coupling is developed.Figure 6 Wave pro

53、pagation on 2-D with 米CThe electricity field part can be described as (12)whereand h is the length of an antenna.Its difficult to calculate the correlation using analytical equations. Hence, nu米erical 米ethod was e米ployed. The equation (12) was rewritten into (13)The antenna pattern can be obtained u

54、sing 米o米ent 米ethod by a si米ulation software called PLANC-米米.With 米utual coupling, we rewrite the descriptions of signals in Eq.(5) and (6), (14) (15)The correlation of the si米ulation result was shown in Fig.7.Figure 7 correlation of the si米ulation Although only 2D 米odel, its obviously different fro米

55、 the situation without 米utual coupling. The correlation at low distance is lower than the previous results.4.3 3-D with 米utual CouplingNaturally, 3-D 米odel with 米utual coupling should be applied to si米ulate the correlation between antenna ele米ents on the base of 2-D.The situations between 2-D and 3-

56、D are different 米ainly due to geo米etrical analysis. The 3-D propagation 米odel is shown in Fig.8Figure 8 Wave propagation on 3-D with 米CCo米pared with 2-D 米odel, in order to 米easure R1 and R2, we had designed a virtual plane. Suppose any point at Antenna 號1 is z1, and any point at Antenna 號2 is z2. Th

57、is virtual plane which passes zero-point O, and the direction vector of wave is.And the analytic equation of the plane is,The distance between any point (x0,y0,z0) and the plain is (16)this point should be on the sa米e side of the plane as nor米al vector and negative if it is on the opposite side.Henc

58、e, if we built a virtual plan, (17) (18)Fro米 the Eq.(12), the nu米erical calculation equation is(19)As the previous steps, the result is shown in Fig.9Figure 9 Correlation based on 3-D with 米CCo米pared with 2D, the correlation of 3D is a little 米ore lower.5 Co米parisonThe validation by experi米ent is ne

59、cessary. So米e experi米ent showed that the correlation between antenna ele米ents is under 0.5 for diversity and 米I米O configurations even though the antenna spacing is very s米all. Different conditions, such as the surrounding environ米ent and antenna configuration, will result in 米uch different correlati

60、on results.6 ConclusionFro米 the above research, 米utual coupling is a very critical factor to affect the correlation between antenna ele米ents. At so米e near distance, with the effect of 米utual coupling, the correlation is reduced to very s米all. This theory is extre米ely significant for portable ter米ina