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黃河科技學(xué)院畢業(yè)設(shè)計(jì)(論文)開題報(bào)告表
課題名稱
雷達(dá)頻率機(jī)械調(diào)控機(jī)構(gòu)的設(shè)計(jì)
課題來(lái)源
教師擬訂
課題類型
工程設(shè)計(jì)真實(shí)課題AX
指導(dǎo)教師
學(xué)生姓名
專 業(yè)
機(jī)械設(shè)計(jì)制造及其自動(dòng)化
學(xué) 號(hào)
1、 調(diào)研資料的準(zhǔn)備
根據(jù)任務(wù)書的要求,在做本課題前,查閱了與課題相關(guān)的資料有:機(jī)械設(shè)計(jì)、機(jī)械制圖、機(jī)械制造工藝學(xué)、機(jī)械原理、電子技術(shù)、機(jī)械制造工藝課程設(shè)計(jì)指導(dǎo)書、冶金機(jī)械設(shè)計(jì)、液壓與氣壓傳動(dòng)、AUTODESK INVENTOR二維設(shè)計(jì)軟件和CAD繪圖相關(guān)資料等以及與設(shè)計(jì)相關(guān)的手冊(cè)。
。
二、設(shè)計(jì)的目的與要求
畢業(yè)設(shè)計(jì)是大學(xué)教學(xué)中最后一個(gè)實(shí)踐性教學(xué)環(huán)節(jié),通過(guò)該設(shè)計(jì)過(guò)程,可以檢驗(yàn)學(xué)生所學(xué)的知識(shí),同時(shí)培養(yǎng)學(xué)生處理工程中實(shí)際問題的能力,因此意義特別重大。
要求:查閱文獻(xiàn)資料12種以上,外文資料不少于兩篇。擬定設(shè)計(jì)方案。本設(shè)計(jì)零件在車床、銑床、鉆床上制造加工完成,因零件形狀所致,制造過(guò)程需各種專用夾具。先設(shè)計(jì)零件形狀尺寸,選擇零件所需材料,完成各種專用夾具,然后相應(yīng)的分別在車床、銑床、鉆床上粗加工和精加工,制造出符合要求的零件。最終組裝成機(jī)器,完成整個(gè)機(jī)械設(shè)計(jì)
三、設(shè)計(jì)的思路與預(yù)期成果
(1).了解頻率調(diào)控計(jì)的結(jié)構(gòu)和工作過(guò)程,對(duì)頻率調(diào)控系統(tǒng)進(jìn)行設(shè)計(jì)。
(2).進(jìn)行基本的幾何計(jì)算和受力分析,選擇合適的參數(shù) (3).完成文獻(xiàn)綜述和外文翻譯。
(4).設(shè)計(jì)圖樣(包括總裝圖和主要零部件圖)。 (5).完成畢業(yè)論文,編寫設(shè)計(jì)說(shuō)明書。
四、任務(wù)完成的階段內(nèi)容及時(shí)間安排
1周———4周 完成開題報(bào)告、文獻(xiàn)翻譯、文獻(xiàn)綜述及總體方案設(shè)計(jì)
5周——-10周 完成總體設(shè)計(jì)、完成部分機(jī)構(gòu)的裝配圖及部分零件圖并撰寫說(shuō)明書
10周——11周 修改論文、資格審查等
12周 畢業(yè)答辯
五、完成設(shè)計(jì)(論文)所具備的條件因素
首先完成本次設(shè)計(jì),主觀上要有主動(dòng)性,閱讀與題目相關(guān)的資料等,同時(shí)也必須了解論文的格式,撰寫的方法等等。其次客觀上要具備一定的條件,如通用計(jì)算機(jī),繪圖機(jī),設(shè)計(jì)室,AUTOCAD、SOLIDWORKS、UG、電子圖板等繪圖軟件,有關(guān)參考書、工具書、資料等。
指導(dǎo)教師簽名: 日期:
課題來(lái)源:(1)教師擬訂;(2)學(xué)生建議;(3)企業(yè)和社會(huì)征集;(4)科研單位提供
課題類型:(1)A—工程設(shè)計(jì)(藝術(shù)設(shè)計(jì));B—技術(shù)開發(fā);C—軟件工程;D—理論研究;E—調(diào)研報(bào)告
(2)X—真實(shí)課題;Y—模擬課題;Z—虛擬課題
要求(1)、(2)均要填,如AY、BX等。
黃河科技學(xué)院畢業(yè)設(shè)計(jì)(文獻(xiàn)綜述) 第8頁(yè)
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單位代碼 02
學(xué) 號(hào) 080105037
分 類 號(hào) TH
密 級(jí)
畢業(yè)設(shè)計(jì)
文獻(xiàn)綜述
院(系)名稱
工學(xué)院機(jī)械系
專業(yè)名稱
機(jī)械設(shè)計(jì)制造及其自動(dòng)化
學(xué)生姓名
指導(dǎo)教師
2012年 03 月 18 日
雷達(dá)頻率機(jī)械調(diào)控機(jī)構(gòu)
摘要:雷達(dá)頻率機(jī)械調(diào)控裝置是用于調(diào)節(jié)雷達(dá)頻率的機(jī)械裝置,是雷達(dá)的一個(gè)重要組成部分,本文主要介紹雷達(dá)頻率調(diào)控裝置的一些形式及其發(fā)展歷程,和雷達(dá)頻率調(diào)控裝置中機(jī)械調(diào)控部分的原理,結(jié)構(gòu),參數(shù)的介紹和計(jì)算
關(guān)鍵詞:雷達(dá)、頻率、調(diào)控、機(jī)械、傳動(dòng)
前言:雷達(dá)頻率調(diào)控計(jì),顧名詞義是用于調(diào)節(jié)雷達(dá)頻率的裝置,它要求設(shè)計(jì)的簡(jiǎn)單可控,便捷靈敏,它以機(jī)械傳動(dòng)裝置為主體,配合磁控管的電感銷的上下移動(dòng)來(lái)實(shí)現(xiàn)雷達(dá)頻率的調(diào)節(jié),本設(shè)計(jì)則主要是設(shè)計(jì)其機(jī)械傳功裝置,從而實(shí)現(xiàn)雷達(dá)頻率調(diào)控計(jì)的主要部分。而機(jī)械傳動(dòng)裝置的應(yīng)用范圍非常廣泛,各種機(jī)器,包括汽車,輪船,火車等上面都有許多的機(jī)械傳動(dòng)裝置。此外,機(jī)械傳動(dòng)的方式有很多種,比如齒輪傳動(dòng),帶傳動(dòng),鏈傳動(dòng)等,各種傳動(dòng)方式都有其自身的優(yōu)缺點(diǎn)和適用范圍,這個(gè)要視具體情況而定
頻率調(diào)控器的介紹與比較
變頻器是近幾年在興起的一種調(diào)速節(jié)能新產(chǎn)品,它是電力電子技術(shù)和計(jì)算機(jī)應(yīng)用技術(shù)的完美結(jié)合,因其調(diào)速精度高、操作方便,并且節(jié)約能源(輸出頻率小于50Hz時(shí)),現(xiàn)已被廣泛應(yīng)用在機(jī)械、化工、冶金、輕工等領(lǐng)域。根據(jù)實(shí)際應(yīng)用的需要,彎頻器頻率設(shè)置的方法有不同類型,現(xiàn)說(shuō)明幾種頻率設(shè)置的特點(diǎn)。
變頻器頻率設(shè)置的方法可以分兩大類,第一類是利用變頻器操作面板進(jìn)行頻率設(shè)置,第二類是利用變頻器控制端子進(jìn)行頻率設(shè)置。第一類通過(guò)面板上的鍵盤或電位器進(jìn)行頻率給定(即調(diào)節(jié)頻率)的方式,稱為面板給定方式,它利用變頻器操作面板進(jìn)行頻率設(shè)置,只需操作面板上的上升、下降鍵,就可以實(shí)現(xiàn)頻率的設(shè)定。該方法不需要外部接線,方法簡(jiǎn)單,頻率設(shè)置精度高,屬數(shù)字量頻率設(shè)置,適用于單臺(tái)變頻器的頻率設(shè)置。第二類是利用變頻器控制端子進(jìn)行頻率設(shè)置,又分兩種方法,第一種是利用外接電位器進(jìn)行頻率設(shè)置;第二種是利用變頻器控制端子的特寫功能,用電動(dòng)電位器進(jìn)行頻率設(shè)置。
第一種利用外接電位器進(jìn)行頻率設(shè)置,如圖1,F(xiàn)R-500系列變頻器的10端子提供標(biāo)準(zhǔn)的10V直流電壓,2端子是頻率設(shè)定輸入端,5端子是模擬量輸入公共端子。通過(guò)調(diào)整外接電位器R的2端輸出電壓,改變了變頻器2端的輸入電壓值,也就改變了變頻器的頻率設(shè)定值,達(dá)到了頻率設(shè)置的目的,該方法有以下優(yōu)點(diǎn):
(1) 接線簡(jiǎn)單,只需把電位器的三端分接到變頻器的電壓輸入端,電壓輸出端和公共端就可。
(2) 頻率設(shè)置簡(jiǎn)單,操作方便,只需輕輕轉(zhuǎn)動(dòng)外接電位器的旋鈕,就可以進(jìn)行頻率設(shè)置。
(3) 安裝靈活,可以根據(jù)實(shí)際需要,將外接電位器安裝到任何位置,進(jìn)行遠(yuǎn)距離操作。
但是,該方法也有以下缺點(diǎn):
(1) 有溫漂現(xiàn)象,由于電阻值受溫度的影響,當(dāng)外界溫度發(fā)生變化時(shí),電阻值了也就隨之變化,頻率設(shè)定值也就發(fā)生變化。
(2) 抗干擾能力低。當(dāng)周圍有強(qiáng)電磁干擾時(shí),變頻器和外接電位器的連接電纜線內(nèi)會(huì)產(chǎn)生感應(yīng)電壓,使輸入到變頻器2端的電壓值發(fā)生變化,也就使頻率設(shè)定值發(fā)生變化,影響設(shè)定頻率的穩(wěn)定。
(3) 電位器安裝距離受到一定限制。理論上講,變頻器2端的電壓變化范圍是0-10V,但如果外接電位器安裝距離太遠(yuǎn),連接電纜就會(huì)產(chǎn)生壓降,變頻器2端電壓也就達(dá)不到10V,從而使輸出頻率達(dá)不到最高設(shè)定值。
因此,該變頻器頻率設(shè)置方法一般應(yīng)用在調(diào)速精度低、周圍干擾小、環(huán)境溫度變化小的場(chǎng)合,屬模擬量調(diào)節(jié)。
第二種方法是利用變頻器控制端子的特定功能,通過(guò)設(shè)置變頻器的內(nèi)部參數(shù),可以使端子RH、RM成為電動(dòng)電位器,即當(dāng)RH與公共端SD之間接通時(shí),變頻器輸出頻率上升當(dāng)RM與SD之間接通時(shí),變頻器輸出頻率下降達(dá)到頻率設(shè)置的目的,如圖2,同第一種方法相比,該方法具有以下優(yōu)點(diǎn):
(1) 頻率設(shè)置精度高,外接電位器法屬模擬量設(shè)置方法,頻率變化范圍為最大輸出頻率的±0.2%以內(nèi),而用電動(dòng)電位器設(shè)置頻率,頻率變化范圍為最大輸出頻率的0.01%以內(nèi)。
(2) 抗干擾能力強(qiáng)。由于這它只是開關(guān)信號(hào)輸入,因此不受周圍電磁場(chǎng)的干擾。
(3) 無(wú)溫漂現(xiàn)象。由于取消了外接電位器,因此,不受環(huán)境溫度變化的影響。
(4) 安裝靈活,可以將按鈕SB1,SB2安裝到任何位置。
(5) 同步性能好,可以同時(shí)實(shí)現(xiàn)多臺(tái)變頻器的頻率升高和降低。
總之,我們應(yīng)根據(jù)實(shí)際需要,合理選擇頻率設(shè)置方法,以達(dá)到應(yīng)用效果。
本設(shè)計(jì)是設(shè)計(jì)面板頻率調(diào)控器,并且主要是設(shè)計(jì)其機(jī)械傳動(dòng)裝置,下面對(duì)頻率調(diào)控器的機(jī)械傳動(dòng)裝置作簡(jiǎn)單的介紹
頻率計(jì)的機(jī)械傳動(dòng)裝置
發(fā)動(dòng)機(jī)的轉(zhuǎn)動(dòng)軸帶著工作機(jī)的軸一起轉(zhuǎn)動(dòng),也就是發(fā)動(dòng)機(jī)傳遞到工作機(jī)上。這種轉(zhuǎn)動(dòng)的傳動(dòng)可以用多種不同的方式來(lái)實(shí)現(xiàn)。常見的三種機(jī)械傳動(dòng)方式是皮帶傳動(dòng)、摩擦傳動(dòng)和齒輪傳動(dòng)。
在皮帶傳動(dòng)里,發(fā)動(dòng)機(jī)和工作機(jī)的軸上各裝一個(gè)皮帶輪,輪上緊套著一圈(或并列的幾圈)皮帶(圖1).發(fā)動(dòng)機(jī)軸上的皮帶輪A叫做主動(dòng)輪,工作機(jī)軸上的皮帶輪B叫做從動(dòng)輪。主動(dòng)輪轉(zhuǎn)動(dòng)時(shí),依靠摩擦作用使皮帶運(yùn)動(dòng),皮帶的運(yùn)動(dòng)又帶動(dòng)從動(dòng)輪轉(zhuǎn)動(dòng)。在轉(zhuǎn)動(dòng)時(shí),一般不允許皮帶打滑,這時(shí)兩個(gè)皮帶輪邊緣上的各點(diǎn)線速度相同。因此如果兩個(gè)皮帶輪的直徑不同,他們的角速度或轉(zhuǎn)速也就不同,且角速度或轉(zhuǎn)速跟兩皮帶輪的直徑成反比:
n2/n1=d1/d2
比值n2/n1叫做傳動(dòng)速度比。從上式可知,工作機(jī)軸上的皮帶輪的直徑越小,它的軸的轉(zhuǎn)速就越大。
實(shí)際上常用的傳動(dòng)速度比一般不大于5.這是因?yàn)閭鲃?dòng)速度比越大,從動(dòng)輪的直徑就越小,它跟皮帶接觸的圓弧就越短,帶動(dòng)它的摩擦力也就越小。
圖1的兩皮帶輪轉(zhuǎn)動(dòng)方向相同。圖2的兩皮帶輪轉(zhuǎn)動(dòng)方向相反。
在摩擦傳動(dòng)中,兩個(gè)輪互相緊壓著(圖3)。當(dāng)主動(dòng)輪向一個(gè)方向轉(zhuǎn)動(dòng)時(shí),由于兩輪之間的摩擦作用,從動(dòng)輪也發(fā)生轉(zhuǎn)動(dòng),它的轉(zhuǎn)動(dòng)方向跟主動(dòng)輪相反。
在皮帶傳動(dòng)和摩擦傳動(dòng)中,對(duì)從動(dòng)輪來(lái)說(shuō)摩擦力是動(dòng)力,必須設(shè)法使它增大,因?yàn)橐媚Σ烈驍?shù)比較大的材料如皮革、橡膠,填充石梯的鋼絲等包在輪緣上,還要增大壓力。
如果所傳遞的功率是P,那么有P=fv和v=дdn。可求出作用在輪緣上的摩擦力:
f=P/дdn,
作用在輪緣上使輪轉(zhuǎn)動(dòng)的摩擦力矩:
M=fd/2
一般來(lái)說(shuō),摩擦傳動(dòng)只能在功率不大(15千瓦以下)的情況下使用,如果所傳遞的功率較大,兩輪就會(huì)發(fā)生滑動(dòng)。為了提高所傳動(dòng)的功率,必須保證兩輪不發(fā)生滑動(dòng),因此在兩輪的輪緣上作出許多齒,使一個(gè)輪的每個(gè)齒能夠嵌入令一個(gè)輪的兩齒之間。這樣,在轉(zhuǎn)動(dòng)時(shí)就不斷地互相嚙合,不會(huì)發(fā)生滑動(dòng),這種輪叫做齒輪。齒輪傳動(dòng)是,兩齒輪的齒距就必須相等。這樣,兩輪的轉(zhuǎn)速就跟它們的齒數(shù)成反比。
齒輪傳動(dòng)裝置在生產(chǎn)技術(shù)上應(yīng)用的非常廣泛,它可以傳遞幾千瓦的功率。當(dāng)主動(dòng)輪和從動(dòng)輪所在的兩軸互相平行時(shí),采用圓柱形齒輪(圖4中A和B):當(dāng)兩軸成90°時(shí),采用截錐形齒輪(圖4中的C和E)。此外,我們還常見到用鏈條來(lái)傳動(dòng)的,這實(shí)際上也是齒輪傳動(dòng)的一種變形。
各種機(jī)床、汽車、拖拉機(jī)等用來(lái)調(diào)節(jié)速度用的機(jī)械變速箱,一般都是用齒輪來(lái)傳動(dòng)的。
雷達(dá)頻率調(diào)控機(jī)構(gòu)的發(fā)展前景
目前雷達(dá)頻率調(diào)控裝置正向著便捷,準(zhǔn)確,自動(dòng)化方向發(fā)展,一般的機(jī)械調(diào)控裝置已不再適應(yīng)現(xiàn)代化雷達(dá)的發(fā)展,雷達(dá)的頻率調(diào)控需要更加迅速,準(zhǔn)確,且能根據(jù)環(huán)境的變化自動(dòng)的進(jìn)行調(diào)節(jié),其中頻率捷變雷達(dá)的技術(shù)已經(jīng)相當(dāng)成熟,現(xiàn)在雷達(dá)的頻率調(diào)控正在向著自動(dòng)化方向發(fā)展,其中基于DDS技術(shù)的自適應(yīng)米波雷達(dá)自適用頻率調(diào)控系統(tǒng)在國(guó)外已經(jīng)發(fā)展成熟,而我國(guó)相對(duì)還比較落后,因此,我們應(yīng)朝著雷達(dá)頻率的自動(dòng)調(diào)控技術(shù)方向發(fā)展,運(yùn)用PLC,單片機(jī)等高技術(shù)手段來(lái)實(shí)現(xiàn)雷達(dá)頻率的自動(dòng)調(diào)控。
參考文獻(xiàn)
1、 李運(yùn)華 機(jī)電控制【M】 北京航空航天大學(xué)出版社,2003
2、 芮延年 機(jī)電一體化系統(tǒng)設(shè)計(jì)【M】 北京機(jī)械工業(yè)出版社,2004
3、 王中杰,余章雄,柴天佑 智能控制綜述【J】 基礎(chǔ)自動(dòng)化,2006(6)
4、 章浩,張西良,周士沖 機(jī)電一體化技術(shù)發(fā)展與應(yīng)用【J】 農(nóng)機(jī)化研究,2006(7)
5、 梁俊彥,李玉翔,機(jī)電一體化技術(shù)發(fā)展與應(yīng)用【J】 科技資訊,2007(9)
6、 鄧星鈡 機(jī)電傳動(dòng)控制(第三版),華中科技大學(xué)出版社,2001
7、 裴仁清 機(jī)電一體化原理,上海大學(xué)出版社,1998
8、 秦曾煌 電工學(xué)—電子技術(shù)(第五版),高等教育出版社,2004
9、 朱龍根 機(jī)械系統(tǒng)設(shè)計(jì)(第二版),機(jī)械工業(yè)出版社
10、 紀(jì)名剛 機(jī)械設(shè)計(jì)(第七版),高等教育出版社,2005
11、 袁峰 UG機(jī)械設(shè)計(jì)工程范例教程【M】,北京機(jī)械工業(yè)出版社2006
12、 王志、張進(jìn)生、于豐業(yè)、王鵬、任秀華 基于模塊化的機(jī)械產(chǎn)品快速設(shè)計(jì)【J】應(yīng)用科技2006.33.2
13、 林德杰 過(guò)程控制儀表及控制系統(tǒng),機(jī)械工業(yè)出版社,2004
14、 丁鷺飛、耿富錄、陳建春 雷達(dá)原理(第四版),電子工業(yè)出版社
15、 濮良貴、紀(jì)名剛 機(jī)械設(shè)計(jì)(第八版),高等教育出版社
II
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畢業(yè)設(shè)計(jì)說(shuō)明書
雷達(dá)頻率機(jī)械調(diào)控機(jī)構(gòu)的設(shè)計(jì)
院(系)名稱
工學(xué)院機(jī)械系
專業(yè)名稱
機(jī)械設(shè)計(jì)制造及其自動(dòng)化
學(xué)生姓名
杰
指導(dǎo)教師
2012年 5 月 10 日
黃河科技學(xué)院畢業(yè)設(shè)計(jì)說(shuō)明書 第 III 頁(yè)
________________________________________________________
雷達(dá)頻率調(diào)節(jié)機(jī)構(gòu)設(shè)計(jì)
摘 要
頻率調(diào)節(jié)機(jī)構(gòu)是雷達(dá)的一個(gè)重要的組成部分。在本設(shè)計(jì)中主要通過(guò)蝸輪蝸桿的傳動(dòng)來(lái)調(diào)節(jié)雷達(dá)頻率,蝸輪蝸桿機(jī)構(gòu)具有結(jié)構(gòu)簡(jiǎn)單、單級(jí)傳動(dòng)比大、結(jié)構(gòu)緊湊,傳動(dòng)平穩(wěn)等特點(diǎn)。
本設(shè)計(jì)介紹了雷達(dá)頻率調(diào)頻機(jī)構(gòu)的現(xiàn)狀,主要介紹了本設(shè)計(jì)的主要零件部分,即蝸輪蝸桿之間的傳動(dòng)特點(diǎn)和連接軸的應(yīng)用與計(jì)算,說(shuō)明了本機(jī)構(gòu)的工作原理和相關(guān)計(jì)算。本設(shè)計(jì)的特點(diǎn)是原理簡(jiǎn)單,工作可靠,生產(chǎn)經(jīng)濟(jì),便于安裝與維修,符合設(shè)計(jì)要求與生產(chǎn)要求。
本設(shè)計(jì)對(duì)蝸輪蝸桿傳動(dòng)比,強(qiáng)度,潤(rùn)滑等方面都進(jìn)行了比較完整的闡述,比較詳細(xì)地對(duì)各傳動(dòng)部分做了具體分析,以確保其在實(shí)際生產(chǎn)中穩(wěn)定高效地工作。并對(duì)本機(jī)構(gòu)的鏈接部分即螺紋鏈接進(jìn)行了說(shuō)明和計(jì)算,滿足了強(qiáng)度,壽命等一系列生產(chǎn)條件。
關(guān)鍵詞 頻率 調(diào)節(jié) 蝸輪 蝸桿 傳動(dòng)
The design of radar frequency regulation mechanism
Abstract
Radar frequency adjustment mechanism is an important part of the rader. In this design mainly through the worm gear transmission to adjust the radar frequency, Worm gear mechanism has the characteristics of simple structure, single stage transmission ratio, compact structure, stable transmission.
The design of the radar frequency FM mechanism present situation, introduced the main design of the main parts, namely the worm between the transmission characteristics and is connected to the shaft with applications and computing, explains the working principle of the mechanism and related calculation.。This design is characterized by simple principle, reliable work, convenient installation and production economy, repair, meets the requirements of design and production requirements
The design have quite complete elaboration,to transmission ratio, strength, lubrication etc of the worm gear,and more detailed on the drive parts did concrete analysis,in order to ensure its in the actual production of stable and efficient work.And the mechanism whereby the threaded portion of the link link are described and calculated, satisfies the intensity, lifetime and a series of production conditions.
Key words frequency regulation worm gear worm drive
目 錄
1 緒論 1
1.1 頻率調(diào)節(jié)機(jī)構(gòu) 1
1.2 蝸輪蝸桿簡(jiǎn)介 2
1.3 本課題研究的背景 3
1.4 探究本課題的研究意義 4
2 雷達(dá)頻率調(diào)節(jié)機(jī)構(gòu)的工作原理和設(shè)計(jì)方案 8
2.1頻率調(diào)節(jié)機(jī)構(gòu)工作原理 8
2.1.1 蝸輪部分 8
2.1.2 蝸桿部分 9
2.1.3 連軸部分 9
2.1.4軸結(jié)構(gòu)設(shè)計(jì) 10
2.1.5 軸扭轉(zhuǎn)剛度 10
2.1.6 磨損分析 11
3 總體設(shè)計(jì)計(jì)算 12
3.1蝸輪蝸桿的傳動(dòng)設(shè)計(jì) 12
3.2.蝸桿、蝸輪的基本尺寸設(shè)計(jì) 18
3.2.1蝸桿基本尺寸設(shè)計(jì) 18
3.2.3 蝸輪軸的尺寸設(shè)計(jì)與校核 19
3.3 軸的計(jì)算設(shè)計(jì) 20
3.3.1 軸的基本計(jì)算 20
3.3.2.軸的校核計(jì)算如表3-3 21
3.3.3 軸承壽命的計(jì)算 23
3.4 螺栓聯(lián)結(jié)的強(qiáng)度計(jì)算 26
3.4.1 螺紋連接的強(qiáng)度計(jì)算 26
3.4.2螺栓聯(lián)接的強(qiáng)度計(jì)算 26
3.4.3螺栓強(qiáng)度計(jì)算 26
3.4.4 螺栓組聯(lián)接的設(shè)計(jì) 27
3.4.5 提高螺紋聯(lián)接強(qiáng)度的措施 27
結(jié)束語(yǔ) 29
致 謝 30
參考文獻(xiàn) 31
黃河科技學(xué)院畢業(yè)設(shè)計(jì)(文獻(xiàn)翻譯) 第12頁(yè)
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單位代碼 0 2
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文獻(xiàn)翻譯
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工學(xué)院機(jī)械系
專業(yè)名稱
機(jī)械設(shè)計(jì)制造及其自動(dòng)化
學(xué)生姓名
指導(dǎo)教師
2012年 03 月 18 日
1.6 EFFECT OF OPERATING
FREQUENCY ON RADAR
Radars have been operated at frequencies as low as 2 MHz (just above the AM broadcast band) and as high as several hundred GHz (millimeter wave region). More usually, radar frequencies might be from about 5 MHz to over 95 GHz. This is a very large extent of frequencies, so it should be expected that radar technology, capabilities, and applications will vary considerably depending on the frequency range at which a radar operates. Radars at a particular frequency band usually have different capabilities and characteristics than radars in other frequency bands. Generally, long range is easier to achieve at the lower frequencies because it is easier to obtain high-power transmitters and physically large antennas at the lower frequencies. On the other hand, at the higher radar frequencies, it is easier to achieve accurate measurements of range and location because the higher frequencies provide wider bandwidth (which determines range accuracy and range resolution) as well as narrower beam antennas for a given physical size antenna (which determines angle accuracy and angle resolution). In the following, the applications usually found in the various radar bands are briefly indicated. The differences between adjacent bands, however, are seldom sharp in practice, and overlap in characteristics between adjacent bands is likely.
HF (3 to 30 MHz).
The major use of the HF band for radar (Chapter 20) is to detect targets at long ranges (nominally out to 2000 nmi) by taking advantage of the refraction of HF energy by the ionosphere that lies high above the surface of the earth. Radio amateurs refer to this as short-wave propagation and use it to communicate over long distances. The targets for such HF radars might be aircraft, ships, and ballistic missiles, as well as the echo from the sea surface itself that provides information about the direction and speed of the winds that drive the sea.
VHF (30 to 300 MHz).
At the beginning of radar development in the 1930s, radars were in this frequency band because these frequencies represented the frontierof radio technology at that time. It is a good frequency for long range air surveillanceor detection of ballistic missiles. At these frequencies, the reflection coefficient on scattering from the earth’s surface can be very large, especially over water, so the constructive interference between the direct signal and the surface-reflected signal can increase significantly the range of a VHF radar. Sometimes this effect can almost double the radar’s range. However, when there is constructive interference that increases the range, there can be destructive interference that decreases the range due to the deepnulls in the antenna pattern in the elevation plane. Likewise, the destructive interference can result in poor low-altitude coverage. Detection of moving targets in clutter is often better at the lower frequencies when the radar takes advantage of the Doppler frequency shift because doppler ambiguities (that cause blind speeds) are far fewer at low frequencies. VHF radars are not bothered by echoes from rain, but they can be affected by multiple-time-around echoes from meteor ionization and aurora. The radar cross section of aircraft at VHF is generally larger than the radar cross section at higher frequencies. VHF radars frequently cost less compared to radars with the same range performance that operate at higher frequencies.
Although there are many attractive advantages of VHF radars for long-range surveillance, they also have some serious limitations. Deep nulls in elevation and poor low-altitude coverage have been mentioned. The available spectral widths assigned to radar at VHF are small so range resolution is often poor. The antenna beamwidths are usually wider than at microwave frequencies, so there is poor resolution and accuracy in angle. The VHF band is crowded with important civilian services such as TV and FM broadcast, further reducing the availability of spectrum space for radar. External noise levels that can enter the radar via the antenna are higher at VHF than at microwave frequencies. Perhaps the chief limitation of operating radars at VHF is the difficulty of obtaining suitable spectrum space at these crowded frequencies.In spite of its limitations, the VHF air surveillance radar was widely used by the Soviet Union because it was a large country, and the lower cost of VHF radars made them attractive for providing air surveillance over the large expanse of that country.8 They have said they produced a large number of VHF air-surveillance radars—some were of very large size and long range, and most were readily transportable. It is interesting to note that VHF airborne intercept radars were widely used by the Germans in World War II. For example, the Lichtenstein SN-2 airborne radar operated from about 60 to over 100 MHz in various models. Radars at such frequencies were not affected by the countermeasure called chaff (also known as window).
UHF (300 to 1000 MHz).
Many of the characteristics of radar operating in the VHF region also apply to some extent at UHF. UHF is a good frequency for Airborne Moving Target Indication (AMTI) radar in an Airborne Early Warning Radar (AEW), as discussed in Chapter 3. It is also a good frequency for the operation of long-range radars for the detection and tracking of satellites and ballistic missiles. At the upper portion of this band there can be found long-range shipboard air-surveillance radars and radars (called wind profilers) that measure the speed and direction of the wind.Ground Penetrating Radar (GPR), discussed in Chapter 21, is an example of what is called an ultrawideband (UWB) radar. Its wide signal bandwidth sometimes covers both the VHF and UHF bands. Such a radar’s signal bandwidth might extend, for instance, from 50 to 500 MHz. A wide bandwidth is needed in order to obtain good range resolution. The lower frequencies are needed to allow the propagation of radar energy into the ground. (Even so, the loss in propagating through typical soil is so high that the ranges of a simple mobile GPR might be only a few meters.) Such ranges are suitable for locating buried power lines and pipe lines, as well as buried objects. If a radar is to see targets located on the surface but within foliage, similar frequencies are needed as for the GPR.
L band (1.0 to 2.0 GHz). This is the preferred frequency band for the operation of long-range (out to 200 nmi) air-surveillance radars. The Air Route Surveillance Radar (ARSR) used for long range air-traffic control is a good example. As one goes up in frequency, the effect of rain on performance begins to become significant, so the radar designer might have to worry about reducing the effect of rain at L-band and higher frequencies. This frequency band has also been attractive for the long-range detection of satellites and defense against intercontinental ballistic missiles.
S band (2.0 to 4.0 GHz). The Airport Surveillance Radar (ASR) that monitors air traffic within the region of an airport is at S band. Its range is typically 50 to 60nmi. If a 3D radar is wanted (one that determines range, azimuth angle, and elevation angle), it can be achieved at S band.
It was said previously that long-range surveillance is better performed at low frequencies and the accurate measurement of target location is better performed at high frequencies. If only a single radar operating within a single frequency band can be used, then S band is a good compromise. It is also sometimes acceptable to use C band as the choice for a radar that performs both functions. The AWACS airborne air-surveillance radar also operates at S band. Usually, most radar applications are best operated in a particular frequency band at which the radar’s performance is optimum. However, in the example of airborne air-surveillance radars, AWACS is found at S band and the U.S. Navy’s E2 AEW radar at UHF. In spite of such a difference in frequency, it has been said that both radars have comparable performance. 9 (This is an exception to the observation about there being an optimum frequency band for each application.)
The Nexrad weather radar operates at S band. It is a good frequency for the observation of weather because a lower frequency would produce a much weaker radar echo signal from rain (since the radar echo from rain varies as the fourth power of the frequency), and a higher frequency would produce attenuation of the signal as it propagates through the rain and would not allow an accurate measurement of rainfall rate. There are weather radars at higher frequencies, but these are usually of shorter range than Nexrad and might be used for a more specific weather radar application than the accurate meteorological measurements provided by Nexrad.
C band (4.0 to 8.0 GHz).
This band lies between S and X bands and has properties in between the two. Often, either S or X band might be preferred to the use of C band, although there have been important applications in the past for C band.
X band (8 to 12.0 GHz).
This is a relatively popular radar band for military applications. It is widely used in military airborne radars for performing the roles of interceptor, fighter, and attack (of ground targets), as discussed in Chapter 5. It is also popular for imaging radars based on SAR and ISAR. X band is a suitable frequency for civil marine radars, airborne weather avoidance radar, airborne doppler navigation radars, and the police speed meter. Missile guidance systems are sometimes at X band. Radars at X band are generally of a convenient size and are, therefore, of interest for applications where mobility and light weight are important and very long range is not a major requirement. The relatively wide range of frequencies available at X band and the ability to obtain narrow beamwidths with relatively small antennas in this band are important considerations for high-resolution applications. Because of the high fre-quency of X band, rain can sometimes be a serious factor in reducing the performance of X-band systems.
Ku, K, and Ka
Bands (12.0 to 40 GHz). As one goes to higher radar frequency, the physical size of antennas decrease, and in general, it is more difficult to generate large transmitter power. Thus, the range performance of radars at frequencies above X band is generally less than that of X band. Military airborne radars are found at Ku band as well as at X band. These frequency bands are attractive when a radar of smaller size has to be used for an application not requiring long range. The Airport Surface Detection Equipment (ASDE) generally found on top of the control tower at major airports has been at Ku band, primarily because of its better resolution than X band. In the original K band, there is a water-vapor absorption line at 22.2 GHz, which causes attenuation that can be a serious problem in some applications. This was discovered after the development of K-band radars began during World War II, which is why both Ku and Ka bands were later introduced. The radar echo from rain can limit the capability of radars at these frequencies.
Millimeter Wave Radar.
Although this frequency region is of large extent, most of the interest in millimeter wave radar has been in the vicinity of 94 GHz where there is a minimum (called a window) in the atmospheric attenuation. (A window is a region of low attenuation relative to adjacent frequencies. The window at 94 GHz is about as wide as the entire microwave spectrum.) As mentioned previously, for radar purposes, the millimeter wave region, in practice, generally starts at 40 GHz or even at higher frequencies. The technology of millimeter wave radars and the propagation effects of the environment are not only different from microwave radars, but they are usually much more restricting. Unlike what is experienced at microwaves, the millimeter radar signal can be highly attenuated even when propagating in the clear atmosphere. Attenuation varies over the millimeter wave region. The attenuation in the 94 GHz window is actually higher than the attenuation of the atmospheric water-vapor absorption line at 22.2 GHz. The one-way attenuation in the oxygen absorption line at 60 GHz is about 12 dB per km, which essentially precludes its application. Attenuation in rain can also be a limitation in the millimeter wave region.
Interest in millimeter radar has been mainly because of its challenges as a frontierto be explored and put to productive use. Its good features are that it is a great place foremploying wide bandwidth signals (there is plenty of spectrum space); radars can havehigh range-resolution and narrow beamwidths with small antennas; hostile electroniccountermeasures to military radars are difficult to employ; and it is easier to have a military radar with low probability of intercept at these frequencies than at lower frequencies. In the past, millimeter wave transmitters were not capable of an average power more than a few hundred watts—and were usually much less. Advances in gyrotrons (Chapter 10) can produce average power many orders of magnitude greater than more conventional millimeter-wave power sources. Thus, availability of high power is not a limitation as it once was.
Laser Radar. Lasers can produce usable power at optical frequencies and in the infrared region of the spectrum. They can utilize wide bandwidth (very short pulses) and can have very narrow beamwidths. Antenna apertures, however, are much smaller than at microwaves. Attenuation in the atmosphere and rain is very high, and performance in bad weather is quite limited. Receiver noise is determined by quantum effects rather than thermal noise. For several reasons, laser radar has had only limited application.
1.6 工作頻率對(duì)雷達(dá)的影響
雷達(dá)已在低至 3hz (剛好高于 AM 廣播頻段)的頻率上工作過(guò),也在高至數(shù)百 GHz(毫米波段)頻率上工作過(guò)。雷達(dá)更常用的頻帶可能為 5陽(yáng)也~95GHz 以上,這是一個(gè)巨大的頻率范圍,所以應(yīng)該可以預(yù)期的是雷達(dá)技術(shù)、性能及應(yīng)用會(huì)顯著依賴于雷達(dá)工作的頻段而變化。不同頻段的雷達(dá)通常具有不同的性能和特性?!?,在低頻段易于獲得遠(yuǎn)程性能,因?yàn)樵诘皖l易于獲得大功率發(fā)射機(jī)和物理上巨大的天線。另一方面,在更高的雷達(dá)頻率上,容易完成距離和位置的精確測(cè)量,因?yàn)楦叩念l率能提供更寬的帶寬(它決定距離精度和分辨率),以及在給定夭線物理尺寸時(shí)更窄的波束(它決定角精度和角分辨率)。下面簡(jiǎn)要介紹不同波段的雷達(dá)應(yīng)用。然而相鄰波段的區(qū)別在實(shí)踐中沒有顯著差別,在特性上可能會(huì)有重疊。高頻(HF. 3—30MHz)
HF頻段的主要用途是被雷達(dá)用來(lái)探測(cè)遠(yuǎn)程目標(biāo)(標(biāo)稱可達(dá)到 2000n mile) ,方法是利用高頻電磁波能量被遠(yuǎn)離地表的電離層折射的特性。無(wú)線電愛好者稱這為短波傳播并用它來(lái)在遠(yuǎn)距離上通信。 HF 雷達(dá)的目標(biāo)可能是飛機(jī)、艦船和彈道導(dǎo)彈,以及來(lái)自海面本身的回波(可提供驅(qū)動(dòng)海面的風(fēng)向及風(fēng)速的信息)。
甚高頻(VHF30—300MHZ)
20 世紀(jì) 30 年代開發(fā)的大多數(shù)早期雷達(dá)都工作在該頻段,因?yàn)樵诋?dāng)時(shí)這些頻率代表無(wú)線電技術(shù)的前沿。它對(duì)遠(yuǎn)程空中監(jiān)視和探測(cè)彈道導(dǎo)彈是很好的頻率。在這些頻率上,地球表面特別是水面散射的反射系數(shù)會(huì)非常大,所以直達(dá)信號(hào)和面反射信號(hào)之間的相長(zhǎng)干涉會(huì)顯著增大 VHF 雷達(dá)的作用距離。然而,當(dāng)有這種效應(yīng)使作用距離翻倍時(shí),會(huì)有伴隨而來(lái)的相消干涉減少作用距離,這是由于在某些仰角上,天線方向圖有深的零點(diǎn)。同樣,相消干涉會(huì)導(dǎo)致低空上差的覆蓋。雷達(dá)利用多普勒頻移探測(cè)雜波中的動(dòng)目標(biāo)時(shí)在低頻上經(jīng)常會(huì)更好,因?yàn)槎嗥绽漳:?導(dǎo)致盲速)在低頻段要少得多。 VHF 雷達(dá)不受雨雜波困擾,但受來(lái)自流星的電離和極光的多次時(shí)間折疊回波的影響。在 VHF 頻段,飛機(jī)的雷達(dá)截面積一般比在更高的頻率上大。 VHF 雷達(dá)在獲得同樣的距離性能時(shí)比工作在更高頻段上的雷達(dá)花費(fèi)要少。盡管甚高頻雷達(dá)對(duì)遠(yuǎn)程監(jiān)視有許多誘人的優(yōu)點(diǎn),但也有很多嚴(yán)重的局限。俯仰上的深零點(diǎn)及差的低空覆蓋之前已經(jīng)提到了。分配給 VHF 雷達(dá)的可用頻譜寬度很窄,因此距離分辨率經(jīng)常很差。天線波束寬度通常比微波頻段的寬,因此角精度和分辨率也差。 VHF 頻段中擁擠著許多重要的民用服務(wù),如電視和調(diào)頻廣播,這進(jìn)一步減少了雷達(dá)可用的頻譜空間。通過(guò)天線進(jìn)入雷達(dá)的外部噪聲電平在 VHF 頻段比微波頻段高。工作在 VHF 頻段,雷達(dá)的主要局限可能是在這個(gè)擁擠的頻段中獲得合適頻譜空間的困難。盡管有局限, VHF 對(duì)空監(jiān)視雷達(dá)在蘇聯(lián)曾廣泛使用,因?yàn)樘K聯(lián)國(guó)土廣大,而 VHF 雷達(dá)的低廉,對(duì)提供疆域這么廣闊國(guó)家的空中監(jiān)視很有吸引力[8] 。據(jù)說(shuō)蘇聯(lián)生產(chǎn)了大量的 VHF 對(duì)空監(jiān)視雷達(dá)一一一些有著非常巨大的只寸和遠(yuǎn)的作用距離,但多數(shù)是可容易運(yùn)輸?shù)摹S幸馑嫉氖?VHF 機(jī)載攔截雷達(dá)曾在第二次世界大戰(zhàn)中被德國(guó)廣泛使用。例如, Lichtenstein SN-2 機(jī)載雷達(dá)在不同型號(hào)中工作在 60~100MHz 上。在這些頻率上的雷達(dá)不受稱為輔條(也稱為窗口)的對(duì)抗措施的影響。
超高頻(UHF.300MHZ—1GHZ)
工作在甚高頻雷達(dá)的許多特點(diǎn)在一定程度上也適合于超高頻。 UHF 特別適合于機(jī)載預(yù)警雷達(dá)系統(tǒng) (AEW) 中的機(jī)載 AMTI (動(dòng)目標(biāo)檢測(cè))雷達(dá)(參見第 3 章),也適于探測(cè)和跟蹤衛(wèi)星和彈道導(dǎo)彈的遠(yuǎn)程雷達(dá)。在這個(gè)波段的上段可找到遠(yuǎn)程艦載對(duì)空監(jiān)視雷達(dá)和測(cè)量風(fēng)速及風(fēng)向的雷達(dá)(稱為風(fēng)靡線雷達(dá))。地面穿透雷達(dá) CGPR) ,是所謂超寬帶 (UWB) 雷達(dá)的例子,參見第 21 章。它寬的信號(hào)帶寬有時(shí)同時(shí)覆蓋 VHF 和 UHF 波段。這種雷達(dá)的信號(hào)帶寬可能從 50MHz延伸到 500MHz。寬的帶寬對(duì)獲得好的距離分辨率是需要的。低頻率對(duì)允許雷達(dá)能量穿透地面?zhèn)鞑ナ切枰?盡管如此,在典型土壤中傳播衰減迅速,因而簡(jiǎn)單的機(jī)動(dòng) GPR 作用距離可能僅有幾米)。這個(gè)距離適合定位掩埋在地F的電線、管線和其他物體。如果雷達(dá)要發(fā)現(xiàn)位于地表但被樹木遮蓋的目標(biāo),也需要同 GPR 所用類似的頻段。
Ku,K和Ka波段(14.0—40.0GHZ)
在更高的雷達(dá)頻率上,天線物理尺寸減小,一般更難產(chǎn)生大的發(fā)射機(jī)功率。因此, X 波段之上頻段的雷達(dá)的距離性能一般不如 X 波段的雷達(dá)。軍用機(jī)載雷達(dá)有 X 波段的,也有 Ku波段的。對(duì)必須要有小的尺寸而不需要遠(yuǎn)距離的雷達(dá)應(yīng)用,這些頻段具有吸引力。機(jī)場(chǎng)表面探測(cè)設(shè)備 CASDE) ,通常在大型機(jī)場(chǎng)控制塔的頂端可以找到,工作在 Ku 波段,主要因?yàn)樗?X 波段有更好的分辨率。在原先的 K 波段中,在 22.2GHz處有一條水蒸氣吸收線,這導(dǎo)致的衰減在一些應(yīng)用中是個(gè)嚴(yán)重的問題。這個(gè)問題當(dāng) K 波段雷達(dá)在第二次世界大戰(zhàn)期間研制開始以后被發(fā)現(xiàn),這就是后來(lái)引入 Ku 和 Ka 波段的原因。雨雜波會(huì)限制該波段雷達(dá)的性能。
毫米波波段
盡管這個(gè)頻段很寬,多數(shù)毫米波雷達(dá)感興趣的頻率位于 94GHz附近,此處的大氣衰減有一個(gè)極小值(稱為窗口,是指相對(duì)于其附近的頻率衰減小的區(qū)域, 94GHz附近的窗口和整個(gè)微波頻段一樣寬)。如上面所提到的,對(duì)雷達(dá)的目的,毫米波范圍實(shí)際上一般從 40GHz甚至更高的頻率開始。毫米波雷達(dá)的技術(shù)和環(huán)境的傳播效應(yīng)不僅不同于微波雷達(dá),而且通常有更多的限制。不同于微波波段雷達(dá)所經(jīng)歷的衰減,毫米波雷達(dá)信號(hào)即使在潔凈的空氣中傳播也會(huì)有很大的衰減。衰減在毫米波段是變化的。 94GHz 窗口中的衰減實(shí)際上比大氣 22.2GHz處的水蒸氣吸收線還要高。在 60GHz 氧氣吸收線處的單程衰減約為 12扭曲,基本上排除了雷達(dá)在其鄰近頻率的應(yīng)用。雨的衰減對(duì)毫米波波段也是一種限制。
對(duì)毫米波雷達(dá)感興趣的主要原因是因?yàn)樗鳛檠芯亢陀谐晒膽?yīng)用的前沿帶來(lái)的挑戰(zhàn)。它的好的特點(diǎn)在于它是采用寬帶寬信號(hào)的極好場(chǎng)所(有大量的頻譜空間);雷達(dá)可使用小的天線得到高距離分辨率和窄波束:敵方難以對(duì)軍用雷達(dá)使用電子對(duì)抗措施:它使位于這些頻率的軍用雷達(dá)比低頻率的雷達(dá)有低的被截獲概率。在過(guò)去,毫米波發(fā)射機(jī)平均功率無(wú)法超過(guò)數(shù)百瓦一一通常要低得多?;匦苌系倪M(jìn)展(參見第 10 章)使得可以產(chǎn)生比傳統(tǒng)的毫米波功率源大幾個(gè)數(shù)量級(jí)的平均功率。因此,獲得大功率不再成為限制。
激光雷達(dá)
激光器在頻譜的光學(xué)和紅外區(qū)可以產(chǎn)生可用的功率。它可使用寬帶寬(極短脈沖)并具有非常窄的波束寬度,而天線孔徑比微波段的小很多。大氣和雨的衰減非常高,因此在惡劣天氣中的性能十分有限。接收機(jī)噪聲由量子效應(yīng)而不是熱噪聲決定。由于幾種原因,激光雷達(dá)的應(yīng)用有限。
1.8 雷達(dá)過(guò)去的一些進(jìn)展
(1)第二次世界大戰(zhàn)之前和第二次世界大戰(zhàn)期間,開發(fā)為防空部署在地面、艦船和軍用
飛機(jī)上的 VHF 雷達(dá)。
(2) 第二次世界大戰(zhàn)早期微波磁控管的發(fā)明和波導(dǎo)技術(shù)的應(yīng)用,以獲得能在微波頻段工
作的雷達(dá),從而可使用更小和機(jī)動(dòng)性更強(qiáng)的雷達(dá)。
(3 )MIT 輻射實(shí)驗(yàn)室在第二次世界大戰(zhàn)期間存在的五年中開發(fā)了超過(guò) 100 種不同的雷達(dá)
型號(hào),為微波雷達(dá)奠定了基礎(chǔ)。
(4) Marcum 的雷達(dá)檢測(cè)理論。
(5) 速調(diào)管和行波管放大器的發(fā)明和發(fā)展,提供了穩(wěn)定性好的大功率源。
(6) 使用多普勒頻移來(lái)檢測(cè)淹沒于雜波中的移動(dòng)目標(biāo)。
(7)適于空中交通管制的雷達(dá)的開發(fā)。
(8) 脈沖壓縮。
(9) 單脈沖跟蹤雷達(dá)有高的跟蹤精度,以及比以前的跟蹤雷達(dá)對(duì)電子對(duì)抗措施有更好
的抵御能力。
(10) 合成孔徑雷達(dá),對(duì)地面場(chǎng)景和地面上的物體成像。
(11) 機(jī)載動(dòng)目標(biāo)顯示 (AMTI) ,用于在有雜波情況下遠(yuǎn)程機(jī)載空中監(jiān)視。
(12) 穩(wěn)定的元件、子系統(tǒng)和超低副瓣天線,使可大量抑制無(wú)用雜波的高 P盯脈沖多普
勒雷達(dá) (AWACS) 成為可能。
(13) 高頻超視距雷達(dá),把飛機(jī)和艦船的探測(cè)距離擴(kuò)大了一個(gè)數(shù)量級(jí)。
(14) 數(shù)字處理,從 20 世紀(jì) 70 年代早期對(duì)雷達(dá)性能的改善有重大影響。
(15) 監(jiān)視雷達(dá)的自動(dòng)檢測(cè)和跟蹤。
(16) 電掃描相控陣?yán)走_(dá)的批量生產(chǎn)。
(17) 逆合成孔徑雷達(dá) CISAR) ,提供目標(biāo)成像,如對(duì)艦船等非合作目標(biāo)識(shí)別需要的圖像。
(18) 多普勒氣象雷達(dá)。
(19) 太空雷達(dá),適于對(duì)如金星等行星進(jìn)行觀測(cè)。
(20) 計(jì)算機(jī)對(duì)復(fù)雜目標(biāo)雷達(dá)截面積的精確計(jì)算。
(21)多功能機(jī)載軍用雷達(dá),體積和質(zhì)量相對(duì)小,適于安裝在戰(zhàn)斗機(jī)前端,具有執(zhí)行大
量不同的雪一空和空地任務(wù)的功能。
以上是對(duì)雷達(dá)過(guò)去一些主要發(fā)展的一點(diǎn)觀點(diǎn)。其他人或許有不同的看法。并非每種重大
的雷達(dá)成就都包括在內(nèi)。如果包括本書其他章節(jié)的內(nèi)容,這個(gè)列表可能會(huì)更長(zhǎng)并包含更多的
例子。但是這個(gè)列表己足以顯示出對(duì)雷達(dá)性能改進(jìn)很重要的進(jìn)展類型。