本文選題：天線陣小型化 + 超方向性波束形成方法��； 參考：《武漢大學(xué)》2014年博士論文

【摘要】：隨著科技的高速發(fā)展,無(wú)論是軍事還是民用,現(xiàn)代電子系統(tǒng)越來(lái)越強(qiáng)調(diào)低成本、高機(jī)動(dòng)化、高隱蔽性、高適應(yīng)性等問(wèn)題。與龐大、笨重、昂貴的大型天線陣列相反,小型天線陣系統(tǒng)復(fù)雜度低,具有建造維護(hù)成本低、架設(shè)管理方便、移動(dòng)靈活等優(yōu)點(diǎn)。然而,小型天線陣在使用某些傳統(tǒng)技術(shù),尤其是常規(guī)波束形成方法時(shí),其性能很差,很難滿足實(shí)際工程的測(cè)向、抑制干擾等要求。因此,在硬件資源受限制的情況下,如何通過(guò)信號(hào)處理手段提升小型天線陣的性能,使得天線陣列在小型化的同時(shí)也能滿足實(shí)際工程要求,不僅是天線工程師需要解決的難題,而且在實(shí)際工程中具有廣泛的應(yīng)用前景和重大意義。 課題基于某雷達(dá)和通信工程背景,針對(duì)小型天線陣自身的特點(diǎn),圍繞超方向性波束形成技術(shù)和超分辨空間譜估計(jì)技術(shù)這兩個(gè)問(wèn)題展開(kāi),并對(duì)相關(guān)的一些問(wèn)題進(jìn)行研究,給出小型天線陣應(yīng)用的基本方法。主要研究?jī)?nèi)容有： 1.針對(duì)超方向性陣列在實(shí)際應(yīng)用中存在的低效率、窄帶寬、對(duì)陣列誤差極其敏感性等問(wèn)題進(jìn)行討論,指出應(yīng)用超方向性陣列需要解決的問(wèn)題；針對(duì)高頻超方向性接收陣列存在的兩大問(wèn)題：低效率和對(duì)陣列誤差極其敏感,提出了一種基于敏感度約束的穩(wěn)健超方向性波束形成方法,通過(guò)選擇一個(gè)合適的敏感度因子,該方法不僅可以很容易地得到相應(yīng)的陣列加權(quán)向量,而且還能夠很方便地在方向性增益、陣列效率以及陣列穩(wěn)健性之間進(jìn)行折中。雖然該方法僅關(guān)注在保證陣列穩(wěn)健性和陣列效率滿足要求的情況下,使陣列指向性增益約束最優(yōu),沒(méi)有考慮形成零陷、低旁瓣等常見(jiàn)的波束圖綜合問(wèn)題,但是它保證了超方向性陣列在可實(shí)現(xiàn)的前提下的最差性能。 2.通過(guò)研究控制旁瓣、零陷與陣列效率之間的關(guān)系,發(fā)現(xiàn)低旁瓣和形成零陷有助于克服超方向性陣列的低效率問(wèn)題,因此,當(dāng)天線陣被校正到接近于理想陣列情況時(shí),可以通過(guò)低旁瓣和形成零陷進(jìn)一步減少高頻超方向性接收陣列的孔徑；基于這個(gè)結(jié)論,結(jié)合凸優(yōu)化技術(shù),本文總結(jié)提出了新的超方向性陣列綜合框架,在這種新的框架中零陷、旁瓣以及敏感度這三大性能指標(biāo)同時(shí)也是控制變量,在不同的陣列校正精度條件下,通過(guò)指定這三個(gè)變量的值,可以很靈活方便地在方向性增益、陣列效率、穩(wěn)健性、低旁瓣以及零陷等性能指標(biāo)間進(jìn)行折中,從而達(dá)到設(shè)計(jì)最優(yōu)的超方向性接收陣列的目的。 3.結(jié)合前述的研究結(jié)果,將信號(hào)稀疏表示技術(shù)引入超方向性接收陣列綜合問(wèn)題中,基于l1范數(shù)約束,l1范數(shù)和l∞范數(shù)的混合范數(shù)約束以及l(fā)2范數(shù)約束三種不同的稀疏表示準(zhǔn)則,分別提出了三種基于稀疏表示的超方向性波束形成方法。這三種方法都可以在保證一定的穩(wěn)健性同時(shí),隨著敏感度的減少,降低波束圖的副瓣,其中基于l2范數(shù)約束的方法可視為可降低旁瓣的敏感度約束超方向性波束形成方法,不僅具有計(jì)算方便簡(jiǎn)單,而且陣列穩(wěn)健性可保持在較高的水平,降低了對(duì)實(shí)際工程條件的要求。 4.針對(duì)MUSIC算法受少快拍數(shù)、低信噪比以及所估計(jì)的信號(hào)源數(shù)等因素的影響,借助適用于少快拍數(shù)、低信噪比的SSMUSIC算法思想,研究了不需要估計(jì)信號(hào)源數(shù)目的高分辨DOA估計(jì)算法。利用信號(hào)特征值與噪聲特征值不一樣的特性,提出了一種新的類似于SSMUSIC算法的空間譜構(gòu)建方法,而在這種SSMUSIC-like空間譜中不必預(yù)知信源數(shù)；類似于上述SSMUSIC-like算法思想,為了避免特征值分解以及降低計(jì)算量,又提出了一種不需要估計(jì)信源數(shù)目的快速高分辨DOA估計(jì)算法,利用協(xié)方差矩陣的逆矩陣,算法先使用Capon算法進(jìn)行粗掃描減少譜峰搜索的范圍,再通過(guò)矩陣高階次冪乘來(lái)構(gòu)造一種具有低運(yùn)算復(fù)雜度的合成空間譜,對(duì)可能存在信號(hào)的區(qū)域進(jìn)行細(xì)掃描實(shí)現(xiàn)信號(hào)“超分辨”。仿真結(jié)果表明,在少快拍數(shù)、低信噪比的條件下,所提出兩種算法不僅不需要估計(jì)信號(hào)源數(shù)目,而且分辨力優(yōu)于MUSIC算法,有助于提升小型天線陣DOA估計(jì)的性能。 5.針對(duì)二階累積量DOA估計(jì)算法在背景噪聲為非高斯白噪聲情況下性能下降以及所估計(jì)的信源數(shù)有限等問(wèn)題,研究了任意陣的四階累積量DOA估計(jì)算法。針對(duì)四階累積量DOA估計(jì)算法計(jì)算量較大的問(wèn)題,提出了一種基于四階累積量擴(kuò)展的快速算法�？焖偎惴ㄏ壤盟碾A累積量陣列擴(kuò)展原理,虛擬擴(kuò)展出個(gè)中心對(duì)稱的天線陣列,然后借助酉變換算法,將整個(gè)DOA估計(jì)過(guò)程從復(fù)數(shù)域變換到實(shí)數(shù)域上,從而降低龐大的復(fù)數(shù)計(jì)算運(yùn)算量,最后結(jié)合不需要估計(jì)信源數(shù)目的快速DOA估計(jì)算法思想,重構(gòu)適當(dāng)?shù)目臻g譜,在避免估計(jì)信號(hào)源個(gè)數(shù)、減少整個(gè)譜峰掃描點(diǎn)數(shù)的同時(shí),又可以獲得良好的DOA估計(jì)性能。通過(guò)計(jì)算復(fù)雜度分析和仿真實(shí)驗(yàn),可以發(fā)現(xiàn)：快速算法不僅可以很好地提升小型天線陣在背景噪聲為非高斯白噪聲條件下的DOA估計(jì)性能,而且也大量增加了小型陣列可以估計(jì)的信號(hào)源數(shù)目。
[Abstract]:With the rapid development of science and technology , whether military or civilian , the modern electronic system emphasizes the problems of low cost , high mobility , high concealment and high adaptability .

Based on the background of a radar and communication engineering , aiming at the characteristics of the small antenna array itself , the two problems about super - directional beam forming technology and super - resolution space spectrum estimation technology are unfolded , and the related problems are studied , and the basic methods of the application of the small antenna array are given .

1 . Aiming at the problems of low efficiency , narrow bandwidth , extremely sensitive array error and so on in the practical application of the super - directional array , it is pointed out that the application of the super - directional array needs to be solved .
Aiming at the two big problems existing in the high - frequency super - directional receiving array : low efficiency and extremely sensitive to the array error , a robust super - directional beam forming method based on sensitivity constraint is proposed .

2 . By studying the relationship between the control side lobe , the zero trapping and the array efficiency , it is found that the low side lobe and the formation of the zero trap can help overcome the low efficiency problem of the super directional array . Therefore , when the antenna array is corrected to close to the ideal array , the aperture of the high frequency super directional receiving array can be further reduced through the low side lobe and the forming zero depression ;
Based on this conclusion , combining the convex optimization technology , this paper summarizes the new super - directional array integrated framework . In this new framework , the three performance indexes of null , side lobe and sensitivity are also the control variables . Under the condition of different array correction accuracy , by specifying the values of these three variables , the directional gain , the array efficiency , the robustness , the low side lobe and the zero - trapping performance index can be easily folded , so as to achieve the purpose of designing the optimal super - directional receiving array .

3 . Combining the above research results , the signal sparse representation technique is introduced into the synthesis problem of the super directional reception array . Three kinds of super directional beam forming methods based on the l1 norm constraint , the l1 norm and the l 鈭，

本文編號(hào)：2031608