實驗名稱：低頻(pin)通信機械天(tian)線性(xing)能測試

　　研究方向：傳統(tong)長波天(tian)(tian)(tian)(tian)線(xian)(xian)(xian)(xian)是(shi)通(tong)(tong)過金屬結構中(zhong)的(de)(de)電(dian)(dian)諧(xie)振(zhen)產生電(dian)(dian)磁(ci)(ci)輻射(she)，因(yin)此(ci)通(tong)(tong)常需要(yao)成百上千米(mi)的(de)(de)尺(chi)(chi)寸來(lai)滿(man)足工作頻率的(de)(de)要(yao)求，不利(li)于安裝和(he)維護。機(ji)(ji)(ji)械天(tian)(tian)(tian)(tian)線(xian)(xian)(xian)(xian)則是(shi)利(li)用機(ji)(ji)(ji)械振(zhen)動帶動材料內部電(dian)(dian)偶極(ji)子或磁(ci)(ci)偶極(ji)子翻轉實現電(dian)(dian)磁(ci)(ci)輻射(she)，能夠(gou)突(tu)破(po)結構尺(chi)(chi)寸與輻射(she)效(xiao)率的(de)(de)限制實現長波天(tian)(tian)(tian)(tian)線(xian)(xian)(xian)(xian)的(de)(de)小型化(hua)(hua)設計。目(mu)前對于機(ji)(ji)(ji)械天(tian)(tian)(tian)(tian)線(xian)(xian)(xian)(xian)的(de)(de)研(yan)究(jiu)主要(yao)集中(zhong)于天(tian)(tian)(tian)(tian)線(xian)(xian)(xian)(xian)輻射(she)效(xiao)率和(he)傳輸距離等(deng)單體天(tian)(tian)(tian)(tian)線(xian)(xian)(xian)(xian)電(dian)(dian)磁(ci)(ci)性能優(you)化(hua)(hua)等(deng)方面，對于機(ji)(ji)(ji)械天(tian)(tian)(tian)(tian)線(xian)(xian)(xian)(xian)信號傳輸系統(tong)的(de)(de)研(yan)究(jiu)尚(shang)未深入(ru)開展。本實驗基于弛(chi)豫鐵電(dian)(dian)陶(tao)瓷材料構建(jian)機(ji)(ji)(ji)械天(tian)(tian)(tian)(tian)線(xian)(xian)(xian)(xian)通(tong)(tong)信系統(tong)，在實際通(tong)(tong)信系統(tong)中(zhong)探究(jiu)所研(yan)制機(ji)(ji)(ji)械天(tian)(tian)(tian)(tian)線(xian)(xian)(xian)(xian)的(de)(de)性能從而進(jin)行深度的(de)(de)優(you)化(hua)(hua)。

　　實驗目的：為機(ji)械(xie)天線(xian)系(xi)統(tong)發射單(dan)元和(he)(he)接收單(dan)元進行性(xing)能測試，對(dui)壓電(dian)機(ji)械(xie)天線(xian)的(de)電(dian)磁輻射極性(xing)理論分析(xi)，進而對(dui)機(ji)械(xie)天線(xian)系(xi)統(tong)發射單(dan)元進行設(she)計和(he)(he)優化(hua)。測試的(de)不同材(cai)料(liao)和(he)(he)尺寸(cun)(cun)壓電(dian)機(ji)械(xie)天線(xian)的(de)阻抗和(he)(he)電(dian)容曲(qu)線(xian)，選擇最佳的(de)機(ji)械(xie)天線(xian)設(she)計材(cai)料(liao)和(he)(he)結構尺寸(cun)(cun)。搭建(jian)壓電(dian)機(ji)械(xie)天線(xian)發射系(xi)統(tong)，設(she)計和(he)(he)優化(hua)機(ji)械(xie)天線(xian)系(xi)統(tong)放(fang)大和(he)(he)饋電(dian)方(fang)(fang)式，提出(chu)最優的(de)機(ji)械(xie)天線(xian)通(tong)信方(fang)(fang)案。

　　測試設備：函數信號發生器、壓電陶瓷、電流探頭、功率放大器、示波器、接收天線、頻(pin)譜儀(yi)等(deng)；

　　實驗過程：信號(hao)發(fa)(fa)射機(ji)(ji)中，發(fa)(fa)射機(ji)(ji)與(yu)天(tian)(tian)(tian)(tian)線之間需要進行連接(jie)，此(ci)連接(jie)處即為天(tian)(tian)(tian)(tian)線饋電(dian)(dian)在整(zheng)個發(fa)(fa)射機(ji)(ji)系統(tong)(tong)中是至(zhi)關(guan)重要的(de)(de)一部(bu)分。在機(ji)(ji)械天(tian)(tian)(tian)(tian)線發(fa)(fa)射系統(tong)(tong)中亦是如此(ci)，和電(dian)(dian)天(tian)(tian)(tian)(tian)線不(bu)同(tong)，壓(ya)電(dian)(dian)機(ji)(ji)械天(tian)(tian)(tian)(tian)線作(zuo)為一種壓(ya)電(dian)(dian)陶瓷(ci)，天(tian)(tian)(tian)(tian)線饋電(dian)(dian)對壓(ya)電(dian)(dian)機(ji)(ji)械天(tian)(tian)(tian)(tian)線自身的(de)(de)諧振特(te)性(xing)不(bu)影響(xiang)，即壓(ya)電(dian)(dian)機(ji)(ji)械天(tian)(tian)(tian)(tian)線的(de)(de)固有(you)諧振特(te)性(xing)只(zhi)和天(tian)(tian)(tian)(tian)線本(ben)身的(de)(de)材(cai)料(liao)、結構等性(xing)質有(you)關(guan)，天(tian)(tian)(tian)(tian)線饋電(dian)(dian)只(zhi)會影響(xiang)壓(ya)電(dian)(dian)機(ji)(ji)械天(tian)(tian)(tian)(tian)線的(de)(de)輸入功率和輻射效率。

　　為了優(you)化機械(xie)天(tian)線饋(kui)電系統，提高壓電機械(xie)天(tian)線的輸入(ru)功率(lv)(lv)和(he)輻射效率(lv)(lv)。選擇環形(xing)天(tian)線作為接收(shou)(shou)(shou)天(tian)線，天(tian)線工作頻(pin)段為20Hz-1MHz，直徑50cm。為了更直觀(guan)顯示接收(shou)(shou)(shou)信號幅度(du)，使用(yong)頻(pin)譜儀作為接收(shou)(shou)(shou)機，接收(shou)(shou)(shou)頻(pin)段9kHz-3GHz，最大分(fen)析(xi)帶(dai)寬1MHz。

　　根據(ju)圖3-13所示的(de)(de)(de)(de)壓(ya)(ya)電(dian)機(ji)(ji)械天(tian)(tian)(tian)線(xian)(xian)測試系(xi)統(tong)，測試和優化天(tian)(tian)(tian)線(xian)(xian)饋(kui)(kui)(kui)電(dian)對(dui)機(ji)(ji)械天(tian)(tian)(tian)線(xian)(xian)射(she)性能的(de)(de)(de)(de)影響。實驗條件設置為系(xi)統(tong)發(fa)(fa)(fa)射(she)和接(jie)收端的(de)(de)(de)(de)距(ju)離是(shi)1米，信(xin)號發(fa)(fa)(fa)生器輸出30kHz-1MHz的(de)(de)(de)(de)連續正弦(xian)信(xin)號信(xin)號峰(feng)峰(feng)值5Vp-p，放(fang)(fang)(fang)大器放(fang)(fang)(fang)大倍(bei)數為9倍(bei)，即(ji)輸入電(dian)壓(ya)(ya)為45Vp-p。半導(dao)體饋(kui)(kui)(kui)電(dian)探針常用于(yu)測量較(jiao)弱的(de)(de)(de)(de)電(dian)流和電(dian)壓(ya)(ya)信(xin)號，具有高靈敏度(du)、低噪聲(sheng)、易(yi)于(yu)操(cao)作等優點，可(ke)直接(jie)將饋(kui)(kui)(kui)電(dian)探針末端放(fang)(fang)(fang)置在(zai)壓(ya)(ya)電(dian)機(ji)(ji)械天(tian)(tian)(tian)線(xian)(xian)表面(mian)(mian)，探針另一端接(jie)放(fang)(fang)(fang)大器輸出端。機(ji)(ji)械天(tian)(tian)(tian)線(xian)(xian)底面(mian)(mian)放(fang)(fang)(fang)置銅板(ban)，使機(ji)(ji)械天(tian)(tian)(tian)線(xian)(xian)底面(mian)(mian)電(dian)極接(jie)地。因為壓(ya)(ya)電(dian)陶瓷在(zai)工作過程中，發(fa)(fa)(fa)生微小的(de)(de)(de)(de)位置偏移就(jiu)會對(dui)振動產生影響，導(dao)致壓(ya)(ya)電(dian)機(ji)(ji)械天(tian)(tian)(tian)線(xian)(xian)的(de)(de)(de)(de)性能變(bian)差，因此，設計了饋(kui)(kui)(kui)電(dian)臺(tai)(tai)。其中塑(su)料夾具和彈(dan)簧對(dui)壓(ya)(ya)電(dian)陶瓷進行固定，饋(kui)(kui)(kui)電(dian)臺(tai)(tai)的(de)(de)(de)(de)金(jin)屬片(pian)中間(jian)夾陶瓷片(pian)，使用電(dian)導(dao)率高的(de)(de)(de)(de)銅或(huo)者銀來充(chong)當饋(kui)(kui)(kui)電(dian)金(jin)屬，下表面(mian)(mian)用來接(jie)地，饋(kui)(kui)(kui)電(dian)臺(tai)(tai)上(shang)表面(mian)(mian)用高溫導(dao)線(xian)(xian)連接(jie)到(dao)饋(kui)(kui)(kui)電(dian)臺(tai)(tai)背板(ban)，方便連接(jie)功放(fang)(fang)(fang)輸出端。

　　實驗結果：基于壓電機(ji)械天線測(ce)試(shi)系統，測(ce)試(shi)不(bu)同材料(liao)(liao)和不(bu)同尺寸的壓電機(ji)械天線電磁輻射(she)性能，驗證(zheng)壓電機(ji)械天線材料(liao)(liao)和結構設計(ji)的可行(xing)性。

　　測試(shi)直(zhi)徑a-15mm，厚(hou)度(du)(du)b=2mm的(de)(de)P5-H和鐵(tie)(tie)電(dian)陶(tao)瓷(ci)在(zai)(zai)30kHz-1MHz時(shi)(shi)的(de)(de)接(jie)(jie)(jie)(jie)收(shou)(shou)功(gong)率(lv)(lv)曲線(xian)(xian)(xian)(xian)。圖(tu)3-18是環形(xing)天(tian)線(xian)(xian)(xian)(xian)SAS-565L在(zai)(zai)頻率(lv)(lv)30kHz-1MHz之間(jian)接(jie)(jie)(jie)(jie)收(shou)(shou)到(dao)的(de)(de)電(dian)磁波信(xin)(xin)號功(gong)率(lv)(lv)。顯然，環形(xing)天(tian)線(xian)(xian)(xian)(xian)接(jie)(jie)(jie)(jie)收(shou)(shou)到(dao)鐵(tie)(tie)電(dian)陶(tao)瓷(ci)的(de)(de)發射功(gong)率(lv)(lv)好于P5-H，因(yin)此，鐵(tie)(tie)電(dian)陶(tao)瓷(ci)有更(geng)(geng)好的(de)(de)電(dian)磁輻(fu)射性(xing)能(neng)(neng)。當(dang)壓電(dian)機械(xie)天(tian)線(xian)(xian)(xian)(xian)的(de)(de)直(zhi)徑a為(wei)(wei)(wei)7.5mm時(shi)(shi)，由圖(tu)3-18(b)可(ke)知，隨著(zhu)機械(xie)天(tian)線(xian)(xian)(xian)(xian)厚(hou)度(du)(du)b的(de)(de)增(zeng)大，壓電(dian)機械(xie)天(tian)線(xian)(xian)(xian)(xian)測試(shi)系統接(jie)(jie)(jie)(jie)收(shou)(shou)端接(jie)(jie)(jie)(jie)收(shou)(shou)功(gong)率(lv)(lv)逐漸(jian)減小，說(shuo)明壓電(dian)機械(xie)天(tian)線(xian)(xian)(xian)(xian)的(de)(de)厚(hou)度(du)(du)越(yue)(yue)薄，天(tian)線(xian)(xian)(xian)(xian)的(de)(de)輻(fu)射效率(lv)(lv)越(yue)(yue)高(gao)(gao)。同理(li)，保持機械(xie)天(tian)線(xian)(xian)(xian)(xian)的(de)(de)厚(hou)度(du)(du)b=2mm，當(dang)機械(xie)天(tian)線(xian)(xian)(xian)(xian)的(de)(de)直(zhi)徑a分別為(wei)(wei)(wei)7.5mm、15mm、30mm時(shi)(shi)，機械(xie)天(tian)線(xian)(xian)(xian)(xian)通信(xin)(xin)系統的(de)(de)接(jie)(jie)(jie)(jie)收(shou)(shou)端接(jie)(jie)(jie)(jie)收(shou)(shou)功(gong)率(lv)(lv)隨著(zhu)a的(de)(de)增(zeng)大逐漸(jian)變(bian)強(qiang)(qiang)(qiang)。作為(wei)(wei)(wei)對比，將鐵(tie)(tie)電(dian)陶(tao)瓷(ci)尺(chi)(chi)寸為(wei)(wei)(wei)a=15mm，b=2mm時(shi)(shi)接(jie)(jie)(jie)(jie)收(shou)(shou)端的(de)(de)接(jie)(jie)(jie)(jie)收(shou)(shou)功(gong)率(lv)(lv)曲線(xian)(xian)(xian)(xian)也放在(zai)(zai)圖(tu)3-18(c)。由圖(tu)3-18(c)可(ke)知，當(dang)壓電(dian)機械(xie)天(tian)線(xian)(xian)(xian)(xian)的(de)(de)輻(fu)射頻率(lv)(lv)超過(guo)(guo)761kHz時(shi)(shi)，尺(chi)(chi)寸為(wei)(wei)(wei)a=15mm，b=2mm的(de)(de)鐵(tie)(tie)電(dian)陶(tao)瓷(ci)有最強(qiang)(qiang)(qiang)的(de)(de)電(dian)磁輻(fu)射。由圖(tu)3-10(b)中的(de)(de)阻抗圖(tu)可(ke)知，當(dang)頻率(lv)(lv)較大時(shi)(shi)，尺(chi)(chi)寸為(wei)(wei)(wei)a=15mm，b=2mm的(de)(de)鐵(tie)(tie)電(dian)陶(tao)瓷(ci)的(de)(de)阻抗更(geng)(geng)接(jie)(jie)(jie)(jie)近(jin)50Ω，因(yin)此，當(dang)頻率(lv)(lv)超過(guo)(guo)721kHz時(shi)(shi)輻(fu)射更(geng)(geng)強(qiang)(qiang)(qiang)。綜上可(ke)知，當(dang)鐵(tie)(tie)電(dian)陶(tao)瓷(ci)的(de)(de)尺(chi)(chi)寸為(wei)(wei)(wei)a=30mm，b=1mm時(shi)(shi)，壓電(dian)機械(xie)天(tian)線(xian)(xian)(xian)(xian)在(zai)(zai)30kHz-721kHz的(de)(de)頻帶內輻(fu)射效率(lv)(lv)越(yue)(yue)高(gao)(gao)，通信(xin)(xin)性(xing)能(neng)(neng)越(yue)(yue)強(qiang)(qiang)(qiang);當(dang)鐵(tie)(tie)電(dian)陶(tao)瓷(ci)的(de)(de)尺(chi)(chi)寸為(wei)(wei)(wei)a=15mm，b=2mm時(shi)(shi)，壓電(dian)機械(xie)天(tian)線(xian)(xian)(xian)(xian)在(zai)(zai)30kHz-761kHz的(de)(de)頻帶內輻(fu)射效率(lv)(lv)越(yue)(yue)高(gao)(gao)，通信(xin)(xin)性(xing)能(neng)(neng)越(yue)(yue)強(qiang)(qiang)(qiang)。

　　功(gong)率放大器推薦：ATA-4014C

　　圖：ATA-4014C高壓功率放大器指標參數

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