天線是一種變換器，它把傳輸線上傳播的導(dǎo)行波，變換成在無(wú)界媒介（通常是自由空間）中傳播的電磁波，或者進(jìn)行相反的變換。在無(wú)線電設(shè)備中用來(lái)發(fā)射或接收電磁波的部件。無(wú)線電通信、廣播、電視、雷達(dá)、導(dǎo)航、電子對(duì)抗、遙感、射電天文等工程系統(tǒng)，凡是利用電磁波來(lái)傳遞信息的，都依靠天線來(lái)進(jìn)行工作。此外，在用電磁波傳送能量方面，非信號(hào)的能量輻射也需要天線。一般天線都具有可逆性，即同一副天線既可用作發(fā)射天線，也可用作接收天線。同一天線作為發(fā)射或接收的基本特性參數(shù)是相同的。這就是天線的互易定理。
發(fā)展歷程
天線是由科學(xué)家波波夫發(fā)明的。
1888年，29歲的波波夫得知德國(guó)著名物理學(xué)家赫茲發(fā)現(xiàn)電磁波的消息后，這位曾經(jīng)立志推廣電燈的年輕科學(xué)家對(duì)朋友們說(shuō)：“我用畢生的精力去安裝電燈，對(duì)于廣闊的俄羅斯來(lái)說(shuō)，只不過(guò)照亮了很小的一角：假如我能指揮磁波，那就可以飛越整個(gè)世界。”
于是，他埋頭研究，向新的目標(biāo)發(fā)起了沖擊。
1894年，波波夫制成了一臺(tái)無(wú)線電接收機(jī)。這臺(tái)接收機(jī)的核心部分用的是改進(jìn)了的金屬屑檢波器，波波夫采用電鈴作終端顯示，電鈴的小錘可以把檢波器里的金屬屑震松。電鈴用一個(gè)電磁繼電器帶動(dòng)，當(dāng)金屬屑檢波器檢測(cè)到電磁波時(shí)，繼電器接通電源，電鈴就響起來(lái)。
有一次，波波夫在實(shí)驗(yàn)中發(fā)現(xiàn)，接收機(jī)檢測(cè)電波的距離突然比往常增大了許多。
“這是怎么回事呢？”波波夫查來(lái)查去，一直找不出原因。
一天，波波夫無(wú)意之中發(fā)現(xiàn)一根導(dǎo)線搭在金屬屑檢波器上。他把導(dǎo)線拿開(kāi)，電鈴便不響了；他把實(shí)驗(yàn)距離縮小到原來(lái)那么近，電鈴又響了起來(lái)。
波波夫喜出望外，連忙把導(dǎo)線接到金屬屑檢波器的一頭，并把檢波器的另一頭接上。經(jīng)過(guò)再次試驗(yàn)，結(jié)果表明使用天線后，信號(hào)傳遞距離劇增。
無(wú)線電天線由此而問(wèn)世。
天線的定義
我們知道，通信、雷達(dá)、導(dǎo)航、廣播、電視等無(wú)線電設(shè)備，都是通過(guò)無(wú)線電波來(lái)傳遞信息的，都需要有無(wú)線電波的輻射和接收。在無(wú)線電設(shè)備中，用來(lái)輻射和接收無(wú)線電波的裝置稱(chēng)為天線。天線為發(fā)射機(jī)或接收機(jī)與傳播無(wú)線電波的媒質(zhì)之間提供所需要的耦合。天線和發(fā)射機(jī)、接收機(jī)一樣，也是無(wú)線電設(shè)備的一個(gè)重要組成部分。
天線的功能
天線輻射的是無(wú)線電波，接收的也是無(wú)線電波，然而發(fā)射機(jī)通過(guò)饋線送入天線的并不是無(wú)線電波，接收天線也不能把無(wú)線電波直接經(jīng)饋線送入接收機(jī)，其中必須經(jīng)過(guò)能量轉(zhuǎn)換過(guò)程。下面我們以無(wú)線電通信設(shè)備為例分析一下信號(hào)的傳輸過(guò)程，進(jìn)而說(shuō)明天線的能量轉(zhuǎn)換作用。
在發(fā)射端，發(fā)射機(jī)產(chǎn)生的已調(diào)制的高頻振蕩電流（能量）經(jīng)饋電設(shè)備輸入發(fā)射天線（饋電設(shè)備可隨頻率和形式不同，直接傳輸電流波或電磁波），發(fā)射天線將高頻電流或?qū)Рǎ芰浚┺D(zhuǎn)變?yōu)闊o(wú)線電波—自由電磁波（能量）向周?chē)臻g輻射（見(jiàn)圖1）；在接收端，無(wú)線電波（能量）通過(guò)接收天線轉(zhuǎn)變成高頻電流或?qū)Рǎ芰浚┙?jīng)饋電設(shè)備傳送到接收機(jī)。從上述過(guò)程可以看出，天線不但是輻射和接收無(wú)線電波的裝置，同時(shí)也是一個(gè)能量轉(zhuǎn)換器，是電路與空間的界面器件。
工作原理
當(dāng)導(dǎo)體上通以高頻電流時(shí)，在其周?chē)臻g會(huì)產(chǎn)生電場(chǎng) 與磁場(chǎng)。按電磁場(chǎng)在空間的分布特性，可分為近區(qū)，中間區(qū)， 遠(yuǎn)區(qū)。設(shè)R為空間一點(diǎn)距導(dǎo)體的距離，在 R ﹤﹤ λ/2π 時(shí)的區(qū)域稱(chēng)近區(qū)，在該區(qū)內(nèi)的電磁場(chǎng)與導(dǎo)體中電流,電壓有緊密的聯(lián)系。在R﹥﹥?chǔ)?2π的區(qū)域稱(chēng)為遠(yuǎn)區(qū)，在該區(qū)域內(nèi)電磁場(chǎng)能離開(kāi)導(dǎo)體向空間傳播，它的變化相對(duì)于導(dǎo)體上的電流電壓就要滯后一段時(shí)間，此時(shí)傳播出去的電磁波已不與導(dǎo)線上的電流、電壓有直接的聯(lián)系了，這區(qū)域的電磁場(chǎng)稱(chēng)為輻射場(chǎng)。
必須指出，當(dāng)導(dǎo)線的長(zhǎng)度 L 遠(yuǎn)小于波長(zhǎng) λ 時(shí)，輻射很微弱；導(dǎo)線的長(zhǎng)度 L增大到可與波長(zhǎng)相比擬時(shí)，導(dǎo)線上的電流將大大增加，因而就能形成較強(qiáng)的輻射。
發(fā)射天線正是利用輻射場(chǎng)的這種性質(zhì)，使傳送的信號(hào)經(jīng)過(guò)發(fā)射天線后能夠充分地向空間輻射。如何使導(dǎo)體成為一個(gè)有效輻射體導(dǎo)系統(tǒng)呢？這里先分析一下傳輸線上的情況，在平行雙線的傳輸線上為了使只有能量的傳輸而沒(méi)有輻射，必須保證兩線結(jié)構(gòu)對(duì)稱(chēng)，線上對(duì)應(yīng)點(diǎn)電流大小和方向相反，且兩線間的距離<π。要使電磁場(chǎng)能有效地輻射出去，就必須破壞傳輸線的這種對(duì)稱(chēng)性，如采用把二導(dǎo)體成一定的角度分開(kāi)，或是將其中一邊去掉等方法，都能使導(dǎo)體對(duì)稱(chēng)性破壞而產(chǎn)生輻射。
分類(lèi)
1、按工作性質(zhì)可分為發(fā)射天線和接收天線。
2、按用途可分為通信天線、廣播天線、電視天線、雷達(dá)天線等。
3、按方向性可分為全向天線和定向天線等。
4、按工作波長(zhǎng)可分為超長(zhǎng)波天線、長(zhǎng)波天線、中波天線、短波天線、超短波天線、微波天線等。
5、按結(jié)構(gòu)形式和工作原理可分為線天線和面天線等。描述天線的特性參量有方向圖、方向性系數(shù)、增益、輸入阻抗、輻射效率、極化和頻寬。
6、按維數(shù)來(lái)分可以分成兩種類(lèi)型：一維天線和二維天線
一維天線：由許多電線組成，這些電線或者像手機(jī)上用到的直線，或者是一些靈巧的形狀，就像出現(xiàn)電纜之前在電視機(jī)上使用的老兔子耳朵。單極和雙極天線是兩種最基本的一維天線。
二維天線：變化多樣，有片狀（一塊正方形金屬）、陣列狀（組織好的二維模式的一束片）、喇叭狀、碟狀。
7、天線根據(jù)使用場(chǎng)合的不同可以分為：手持臺(tái)天線、車(chē)載天線、基地天線三大類(lèi)。
手持臺(tái)天線：就是個(gè)人使用手持對(duì)講機(jī)的天線，常見(jiàn)的有橡膠天線和拉桿天線兩大類(lèi)。
車(chē)載天線：是指原設(shè)計(jì)安裝在車(chē)輛上通訊天線，常見(jiàn)應(yīng)用普遍的是吸盤(pán)天線。車(chē)載天線結(jié)構(gòu)上也有縮短型、四分之一波長(zhǎng)、中部加感型、八分之五波長(zhǎng)、雙二分之一波長(zhǎng)等形式的天線。
基地臺(tái)天線：在整個(gè)通訊系統(tǒng)中具有非常關(guān)鍵的作用，尤其是作為通訊樞紐的通信臺(tái)站。常用的基地臺(tái)天線有玻璃鋼高增益天線、四環(huán)陣天線（八環(huán)陣天線）、定向天線。
天線測(cè)量的典型配置
大多數(shù)普通天線的測(cè)量是測(cè)定其遠(yuǎn)場(chǎng)的輻射特性，如方向圖（幅度、相位、極化）、旁瓣電平、增益、頻帶寬度等。本節(jié)將定義這些測(cè)量的基本概念。
圖4為測(cè)量輻射特性的典型配置。基本步驟是將一副發(fā)射或接收的源天線放在相對(duì)于待測(cè)天線（AUT）的遠(yuǎn)場(chǎng)位置上，待測(cè)天線架設(shè)在可旋轉(zhuǎn)平臺(tái)上，旋轉(zhuǎn)待測(cè)天線，借以采集大量方向圖取樣值，實(shí)現(xiàn)天線輻射特性的測(cè)量。由于天線是電磁開(kāi)放系統(tǒng)，測(cè)試環(huán)境對(duì)測(cè)量結(jié)果將產(chǎn)生影響，因此必須合理選擇測(cè)試場(chǎng)地，盡量實(shí)現(xiàn)無(wú)反射的環(huán)境，如建造微波暗室等。
天線測(cè)量中的互易性
天線測(cè)量中被測(cè)天線的工作狀態(tài)可以是發(fā)射狀態(tài)，也可以是接收狀態(tài)。這可根據(jù)測(cè)量的內(nèi)容，測(cè)量的設(shè)備、場(chǎng)地條件等因素靈活選擇。由天線互易原理得知，兩種工作狀態(tài)測(cè)量該天線參數(shù)的結(jié)果應(yīng)該是一致的。
（1）天線必須是線性的、無(wú)源的。
（2）收發(fā)系統(tǒng)阻抗匹配要良好。雖然待測(cè)天線和源天線之間存在多次反射，但由于自由空間傳播的衰減，這種影響并不嚴(yán)重。源天線、饋線、信號(hào)源以及待測(cè)天線、饋線及接收機(jī)，它們相互間的阻抗匹配是滿(mǎn)足互易原理的重要條件。
（3）調(diào)換天線時(shí)，收發(fā)支路無(wú)有源器件，如功率放大器、低噪聲放大器、混頻器等。
[{"ID":"12824901","Picture":"99c876c5d9ae48d997fcb96da771f34373eb46e76bc4db70099e225dfb5ceaa861760371dd68b0b7.jpg","PictureDomain":"img68","Name":"天線分配器D6657","Type":"","Descrip":"◆頻率范圍687~820MHz；◆RF增益-0.5~3dB；◆隔離度≥25dB；◆阻抗50Ω","CompanyName":"廣州市迪士普音響科技有限公司","CompanyID":"6024","MarketPrice":"0","PsOrder":"750","PgID":"87","MaxOrder":"1","CityID":"213","City":"廣州市","Address":"廣州市","PropertysValue":"","HitNumber":"1059","FrontShow":"0","IsCharges":"1","Year":"4","StarNum":"1","UpdateAndClientSort":"50239162","StandUrl":"/st6024","UpdateTime":"2022/6/20 12:42:38","TodayIsUpdate":"0","AttType":"0","AttState":"3","AttAddType":"0","IsSeoCreate":"0","IsOnlinePay":"0","MinPrice":"0.00","MaxPrice":"0.00","ClassID":"21046","productonlinetime":"1900/1/1 0:00:00","OnLineDate":"1900/1/1 0:00:00","DownLineDate":"1900/1/1 0:00:00","BrandPicDomin":"","BrandPicName":"","BrandProperty":"","PBrandID":"0","IsHadVideo":"0","VideoTime":"0","ShowPrice":"0.00","IndustrySort":"11620750","HasPicSort":"112824901","UserID":"8575","PriceType":"0","PictureID":"7499018","CompanyTypeID":"1","Tag":"","LinkMan":"經(jīng)理","TelPhone":"020-28346168","ClassName":"分配器","ComProduct":"廣播系統(tǒng)","BrandNameCH":"","IsShow":"1","MarketPrice2":"0","RetailPrice":"0","ComHitnumber":"43215","MarketUpdateTime":"","CreateTime":"2022/6/20 12:42:38","Flag":"1","PackageName":"VIP1星","ClientSort":"0","CsName":"","Reprint":"","FeedBackMsg":"","EnUrl":"","MobilePhone":""},{"ID":"13312509","Picture":"bc84567bfd36087e9d5cfa70391a7769dd920e09775f9bf44b0af4db6b6ca91204a96900b355c742.jpg","PictureDomain":"img61","Name":"配電改造項(xiàng)目無(wú)線計(jì)量模塊","Type":"AEW100-D15WX","Descrip":"配電改造項(xiàng)目無(wú)線計(jì)量模塊用于計(jì)量低壓網(wǎng)絡(luò)的三相有功電能，具有 RS485 通訊和 470MHz 無(wú)線通訊功能，方便用戶(hù)進(jìn)行用電監(jiān)測(cè)、集抄和管理","CompanyName":"江蘇安科瑞電器制造有限公司","CompanyID":"214677","MarketPrice":"595","PsOrder":"5456","PgID":"89","MaxOrder":"6","CityID":"87","City":"無(wú)錫市","Address":"無(wú)錫市","PropertysValue":"","HitNumber":"1015","FrontShow":"0","IsCharges":"1","Year":"5","StarNum":"6","UpdateAndClientSort":"51597452","StandUrl":"/st214677","UpdateTime":"2025/1/18 18:52:04","TodayIsUpdate":"0","AttType":"0","AttState":"3","AttAddType":"0","IsSeoCreate":"0","IsOnlinePay":"0","MinPrice":"0.00","MaxPrice":"0.00","ClassID":"22294","productonlinetime":"1900/1/1 0:00:00","OnLineDate":"1900/1/1 0:00:00","DownLineDate":"1900/1/1 0:00:00","BrandPicDomin":"img70","BrandPicName":"8/20230221/638125700050513709989.jpg","BrandProperty":"Acrel/安科瑞","PBrandID":"187","IsHadVideo":"0","VideoTime":"0","ShowPrice":"0.00","IndustrySort":"10825456","HasPicSort":"113312509","UserID":"237381","PriceType":"0","PictureID":"8127568","CompanyTypeID":"3","Tag":"無(wú)線計(jì)量,電能計(jì)量,外置天線,開(kāi)口互感器,lora通訊","LinkMan":"陳聰","TelPhone":"86-0510-86179909","ClassName":"電力儀表","ComProduct":"儀器儀表制造，儀器儀表銷(xiāo)售，電子產(chǎn)品銷(xiāo)售","BrandNameCH":"","IsShow":"1","MarketPrice2":"595","RetailPrice":"595","ComHitnumber":"107133","MarketUpdateTime":"2023/7/3 13:47:35","CreateTime":"2023/7/3 13:47:35","Flag":"1","PackageName":"中級(jí)會(huì)員","ClientSort":"0","CsName":"荃荃","Reprint":"","FeedBackMsg":"","EnUrl":"","MobilePhone":"18761595061"},{"ID":"13238096","Picture":"5eceadd4559dcfd213f04a2ae9784057f0c5fde31c986f9a476eb39267f2c24d89bc14d676ffc941.jpg","PictureDomain":"img69","Name":"安科瑞AEW100-D36X無(wú)線計(jì)量電能表 外置天線吸盤(pán) 分表計(jì)電表頭","Type":"AEW100-D36X","Descrip":"簡(jiǎn)單介紹：分表計(jì)電項(xiàng)目AEW100-D15X無(wú)線計(jì)量電表計(jì)量低壓網(wǎng)絡(luò)的三相有功電能分表計(jì)電項(xiàng)目AEW100-D15X無(wú)線計(jì)量電表RS485通訊和470MHz無(wú)線通訊功能詳情介紹：分表計(jì)電項(xiàng)目AEW100-D15X無(wú)線計(jì)量電表概述：功能：AEW100無(wú)線計(jì)量?jī)x表主要用于計(jì)量低壓網(wǎng)絡(luò)的三相有功電能，具有RS485通訊和470MHz無(wú)線通訊功能，方便用戶(hù)進(jìn)行用電監(jiān)測(cè)、集抄和管理","CompanyName":"安科瑞電氣股份有限公司","CompanyID":"233627","MarketPrice":"840","PsOrder":"4826","PgID":"89","MaxOrder":"5","CityID":"394","City":"上海","Address":"上海","PropertysValue":"","HitNumber":"679","FrontShow":"0","IsCharges":"1","Year":"3","StarNum":"1","UpdateAndClientSort":"51196806","StandUrl":"/st233627","UpdateTime":"2024/4/15 13:26:20","TodayIsUpdate":"0","AttType":"0","AttState":"3","AttAddType":"0","IsSeoCreate":"0","IsOnlinePay":"0","MinPrice":"0.00","MaxPrice":"0.00","ClassID":"21563","productonlinetime":"1900/1/1 0:00:00","OnLineDate":"1900/1/1 0:00:00","DownLineDate":"1900/1/1 0:00:00","BrandPicDomin":"img65","BrandPicName":"8/20230313/638143114209695335157.jpg","BrandProperty":"安科瑞/Acrel","PBrandID":"145","IsHadVideo":"0","VideoTime":"0","ShowPrice":"0.00","IndustrySort":"10824826","HasPicSort":"113238096","UserID":"256341","PriceType":"0","PictureID":"8019476","CompanyTypeID":"3","Tag":"","LinkMan":"張?zhí)锾?,"TelPhone":"17821939855","ClassName":"電表","ComProduct":"電力、環(huán)保、新能源、消防、數(shù)據(jù)中心、智能樓宇、智慧校園、智慧醫(yī)院、智慧工廠、智慧交通","BrandNameCH":"安科瑞","IsShow":"1","MarketPrice2":"840","RetailPrice":"840","ComHitnumber":"45688","MarketUpdateTime":"2023/4/28 13:52:39","CreateTime":"2023/4/24 20:22:01","Flag":"1","PackageName":"中級(jí)會(huì)員","ClientSort":"0","CsName":"安安","Reprint":"0","FeedBackMsg":"","EnUrl":"","MobilePhone":"17821939855"},{"ID":"5595347","Picture":"d7dcb51f52fae52abf2e7cf834b6b7433a0228ab8edadec22e29082aa3c01267bd742239ee140ba9.png","PictureDomain":"img74","Name":"XBF-6，XBJ-3，XB2-10 船用鞭狀天線","Type":"","Descrip":"XBF-6，XBJ-3，XB2-10 船用鞭狀天線
本產(chǎn)品適用于各類(lèi)艦船，可與中短波發(fā)訊機(jī)和各種收訊機(jī)、定位儀等設(shè)備配套，用來(lái)發(fā)射和接收無(wú)線電信號(hào)。","CompanyName":"上海經(jīng)馳實(shí)業(yè)有限公司","CompanyID":"31091","MarketPrice":"0","PsOrder":"4478","PgID":"121","MaxOrder":"5","CityID":"3","City":"上海市","Address":"上海市","PropertysValue":"","HitNumber":"3222","FrontShow":"0","IsCharges":"1","Year":"15","StarNum":"3","UpdateAndClientSort":"51308085","StandUrl":"/st31091","UpdateTime":"2024/7/1 20:05:06","TodayIsUpdate":"0","AttType":"0","AttState":"3","AttAddType":"0","IsSeoCreate":"","IsOnlinePay":"0","MinPrice":"0.00","MaxPrice":"0.00","ClassID":"22427","productonlinetime":"1900/1/1 0:00:00","OnLineDate":"1900/1/1 0:00:00","DownLineDate":"1900/1/1 0:00:00","BrandPicDomin":"","BrandPicName":"","BrandProperty":"","PBrandID":"0","IsHadVideo":"0","VideoTime":"0","ShowPrice":"0.00","IndustrySort":"10824478","HasPicSort":"105595347","UserID":"40517","PriceType":"0","PictureID":"3245700","CompanyTypeID":"3","Tag":"XBJ-3,XBF-6,XB2-10,船用鞭狀天線,船用天線","LinkMan":"章鵬宇","TelPhone":"021-33763669","ClassName":"天線","ComProduct":"高壓電器、輸送帶保護(hù)裝置、起重機(jī)控制設(shè)備、通風(fēng)設(shè)備","BrandNameCH":"上海經(jīng)馳","IsShow":"1","MarketPrice2":"0","RetailPrice":"0","ComHitnumber":"2241323","MarketUpdateTime":"2017/7/19 13:18:34","CreateTime":"2015/2/5 13:47:18","Flag":"1","PackageName":"特殊中級(jí)會(huì)員","ClientSort":"0","CsName":"安安","Reprint":"","FeedBackMsg":"","EnUrl":"","MobilePhone":"13795303006"},{"ID":"11955174","Picture":"1697e381d5facf789d68a9caad96c5fc21f871f955dfb1e8b35c9d71aef013dc14ed31e0aba2b36d.jpg","PictureDomain":"img68","Name":"鐵三角寬頻帶同軸式天線增益器ATW-B80WB","Type":"鐵三角ATW-B80WB","Descrip":"鐵三角寬頻帶同軸式天線增益器ATW-B80WB,專(zhuān)為影視制作和廣播采訪（ENG/EFP）的音頻收音而設(shè)計(jì)。超指向性電容話(huà)筒麥克風(fēng)長(zhǎng)度可配合於電子新聞採(cǎi)集、戶(hù)外錄音和其他特別需求的使用。提供窄角度的超指向性能，給與遠(yuǎn)距離的收音效果。由話(huà)筒兩旁到后方均有更佳抗噪音能力。設(shè)有高通濾波開(kāi)關(guān)。可以使用電池或幻象供電工作。","CompanyName":"北京盛世音盟電子科技有限公司","CompanyID":"180346","MarketPrice":"1796","PsOrder":"4032","PgID":"89","MaxOrder":"5","CityID":"1","City":"北京市","Address":"北京市","PropertysValue":"","HitNumber":"4511","FrontShow":"0","IsCharges":"1","Year":"7","StarNum":"4","UpdateAndClientSort":"51313241","StandUrl":"/st180346","UpdateTime":"2024/7/5 10:01:13","TodayIsUpdate":"0","AttType":"0","AttState":"3","AttAddType":"0","IsSeoCreate":"0","IsOnlinePay":"0","MinPrice":"0.00","MaxPrice":"0.00","ClassID":"22427","productonlinetime":"1900/1/1 0:00:00","OnLineDate":"1900/1/1 0:00:00","DownLineDate":"1900/1/1 0:00:00","BrandPicDomin":"","BrandPicName":"","BrandProperty":"","PBrandID":"0","IsHadVideo":"1","VideoTime":"30","ShowPrice":"111111.00","IndustrySort":"10824032","HasPicSort":"111955174","UserID":"203032","PriceType":"0","PictureID":"6562789","CompanyTypeID":"1","Tag":"鐵三角ATW-B80WB,ATW-B80WB,鐵三角","LinkMan":"王凱","TelPhone":"010-85756855","ClassName":"天線","ComProduct":"音箱，話(huà)筒，調(diào)音臺(tái)，聲卡，耳機(jī)","BrandNameCH":"T-CLASS","IsShow":"1","MarketPrice2":"1796","RetailPrice":"1796","ComHitnumber":"383011","MarketUpdateTime":"2020/12/1 14:51:36","CreateTime":"2020/5/22 7:53:51","Flag":"1","PackageName":"中級(jí)會(huì)員","ClientSort":"0","CsName":"安安","Reprint":"","FeedBackMsg":"","EnUrl":"","MobilePhone":"17310032793"}]
◆頻率范圍687~820MHz；◆RF增益-0.5~3dB；◆隔離度≥25dB；◆阻抗50Ω
配電改造項(xiàng)目無(wú)線計(jì)量模塊用于計(jì)量低壓網(wǎng)絡(luò)的三相有功電能，具有 RS485 通訊和 470MHz 無(wú)線通訊功能，方便用戶(hù)進(jìn)行用電監(jiān)測(cè)、集抄和管理
簡(jiǎn)單介紹：分表計(jì)電項(xiàng)目AEW100-D15X無(wú)線計(jì)量電表計(jì)量低壓網(wǎng)絡(luò)的三相有功電能分表計(jì)電項(xiàng)目AEW100-D15X無(wú)線計(jì)量電表RS485通訊和470MHz無(wú)線通訊功能詳情介紹：分表計(jì)電項(xiàng)目AEW100-D15X無(wú)線計(jì)量電表概述：功能：AEW100無(wú)線計(jì)量?jī)x表主要用于計(jì)量低壓網(wǎng)絡(luò)的三相有功電能，具有RS485通訊和470MHz無(wú)線通訊功能，方便用戶(hù)進(jìn)行用電監(jiān)測(cè)、集抄和管理
XBF-6，XBJ-3，XB2-10 船用鞭狀天線
鐵三角寬頻帶同軸式天線增益器ATW-B80WB,專(zhuān)為影視制作和廣播采訪（ENG/EFP）的音頻收音而設(shè)計(jì)。超指向性電容話(huà)筒麥克風(fēng)長(zhǎng)度可配合於電子新聞採(cǎi)集、戶(hù)外錄音和其他特別需求的使用。提供窄角度的超指向性能，給與遠(yuǎn)距離的收音效果。由話(huà)筒兩旁到后方均有更佳抗噪音能力。設(shè)有高通濾波開(kāi)關(guān)。可以使用電池或幻象供電工作。
