中心議題：

• 現代通信係統的天線需求
• 螺旋天線的係統性能
• 雙錐型天線的係統性能

duonianyilai，junshiyingyongyizhixuyaokuandaitongxinlianluyijiyongyouyuzhidaikuanxiangtongdetianxian。tongchang，tianxianbixugongzuozaiduogebeipinchengdefanweishang。yinci，renmenshejizhizaolerongliangweiduogebeipinchengdetianxianjiagou。shishizhengming，zhexiejishuzaishejixiandaitongxinxitongdetianxianchanpinshishifenyouxiao。benwenhuiguleshangyongtongxinxitongdejinhuaguocheng，youqishiduixinpindaibuduanzengchangdexuqiu，ranhoujizhongtaolunleliangzhongzhidejingxiyanjiudetianxianleixing—螺旋和雙錐型天線。

現代通信需求

許多通信係統需要覆蓋900MHz頻段。隨著網絡的進化，人們將其他一些1700到2200MHz內的頻段用於DCS，PCS和UMTS。除了這些頻率以外，通常需要覆蓋的範圍還包括TETRA（大約400MHz）
，無線局域網和無線本地環路（大約2500，3500和5500MHz）。為了滿足所有這些需求，天線必須提供400MHz到6GHz的有效覆蓋。

在zai某mou些xie應ying用yong中zhong可ke以yi采cai用yong一yi係xi列lie獨du立li天tian線xian來lai滿man足zu要yao求qiu，這zhe些xie天tian線xian中zhong的de每mei一yi個ge都dou工gong作zuo於yu一yi個ge特te定ding頻pin帶dai。然ran而er，為wei了le避bi免mian使shi用yong多duo種zhong類lei型xing天tian線xian使shi外wai形xing更geng合he理li
，通tong常chang最zui好hao的de選xuan擇ze是shi用yong一yi個ge單dan天tian線xian提ti供gong對dui整zheng個ge頻pin段duan的de覆fu蓋gai。另ling外wai
，僅jin使shi用yong一yi個ge天tian線xian有you一yi些xie額e外wai的de好hao處chu。除chu了le通tong常chang的de審shen美mei問wen題ti
，還hai有you助zhu於yu確que定ding天tian線xian安an裝zhuang的de設she計ji方fang案an
，避bi免mian天tian線xian引yin起qi新xin建jian築zhu內nei其qi它ta幹gan淨jing的de走zou線xian發fa生sheng混hun亂luan，從cong而er滿man足zu建jian築zhu上shang的de需xu要yao。

duitianxiandeyaoqiubaokuoduopindainengli，qipindaikenengshigudinghuoyidongjierudianyijijizhandepindai，zheshiyinweiduoshuxiandaideshebeibeishejiweiduogongnengde。zhezhongduogongnengxingzhengshixuduoxiandaixitongsuojuyoudexiyinlideyibufen。zhuanyeyonghuxuyaoshebeibuyongtiaozhenggongzuomoshijiunenggongzuo。yinci，wulunshijierudianhaishiyonghu，qigongzuopindaideqiehuanbixushiwufengde。ruguogeidingxitongzhongdemougeyonghuxuyaoyidong，nametianxiandefushetuyangjiuyaoshiquanxiangde，zheyangwulunyonghuxiangduiyulinjinjierudiandeyidongfangxiangruhedounengquebaofugai。zaigudingxitongzhong，yonghutianxiankenengxuyaoshifangxiangxingde，qifangxiangduizhunzuijindejizhanyihuodezuijiaxingneng。jizhandepeizhikeyiyouduozhongfangshi。youshixuyaoshiyongyigequanxiangjizhanbingjiangqifangzaifugaiquyudezhongxin。qitayixieqingkuangxia
，keyijiangyiqunshanxingtianxianpeizhizaiyichu，meigefugaihuanraojizhandeyigeshanxingquyu。xitongtongchangshiyongdeshanxingjiaodubaokuodao。xitongzhongshiyongdejihuaqingkuangyeduozhongduoyang。kenengshixianxingchuizhijihua，shuipinghuoqingxiejihua

，shenzhishiyuanjihua。jihuafangshigenjuxitongxieyihejiegoubianhua
，meizhonggeyouyoudian。tongguoshiyongfujiatianxianxitongkeyihuodeewaidehaochu。tongguopeizhikongjianfenji
，jihuafenji，zishiyingtianxian，huoduoshuruduoshuchu（MIMO）天(tian)線(xian)都(dou)可(ke)以(yi)提(ti)高(gao)鏈(lian)接(jie)正(zheng)常(chang)工(gong)作(zuo)下(xia)保(bao)持(chi)可(ke)接(jie)受(shou)信(xin)噪(zao)比(bi)的(de)統(tong)計(ji)概(gai)率(lv)。本(ben)文(wen)的(de)內(nei)容(rong)是(shi)討(tao)論(lun)單(dan)天(tian)線(xian)係(xi)統(tong)性(xing)能(neng)

，而(er)不(bu)是(shi)研(yan)究(jiu)如(ru)何(he)連(lian)接(jie)多(duo)個(ge)天(tian)線(xian)獲(huo)得(de)更(geng)高(gao)的(de)性(xing)能(neng)。
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螺旋天線

螺旋天線很早以前就開始用於軍事應用中的測向和通常的威脅識別。圖1給出了一種典型的2到18GHz腔基螺旋天線
，圖2給(gei)出(chu)了(le)使(shi)用(yong)這(zhe)種(zhong)天(tian)線(xian)進(jin)行(xing)的(de)一(yi)次(ci)電(dian)磁(ci)仿(fang)真(zhen)，顯(xian)示(shi)了(le)此(ci)構(gou)造(zao)不(bu)同(tong)部(bu)分(fen)上(shang)的(de)場(chang)強(qiang)。在(zai)這(zhe)些(xie)應(ying)用(yong)中(zhong)，通(tong)常(chang)要(yao)求(qiu)天(tian)線(xian)的(de)幅(fu)度(du)和(he)相(xiang)位(wei)每(mei)一(yi)個(ge)都(dou)是(shi)統(tong)一(yi)樣(yang)式(shi)。還(hai)要(yao)求(qiu)主(zhu)瓣(ban)應(ying)該(gai)擁(yong)有(you)平(ping)滑(hua)的(de)曲(qu)線(xian)，沒(mei)有(you)任(ren)何(he)拐(guai)點(dian)，即(ji)為(wei)單(dan)調(tiao)的(de)。這(zhe)種(zhong)天(tian)線(xian)典(dian)型(xing)輻(fu)射(she)圖(tu)樣(yang)如(ru)圖(tu)3所suo示shi。通tong常chang這zhe些xie應ying用yong中zhong更geng重zhong要yao的de是shi控kong製zhi波bo束shu形xing狀zhuang並bing使shi各ge個ge天tian線xian元yuan的de性xing能neng匹pi配pei，而er不bu是shi使shi天tian線xian增zeng益yi最zui大da化hua。對dui於yu許xu多duo商shang業ye通tong信xin係xi統tong，更geng重zhong要yao的de是shi給gei某mou個ge區qu域yu有you效xiao地di填tian充chong信xin號hao而er不bu是shi產chan生sheng非fei常chang精jing確que的de波bo束shu形xing狀zhuang。

圖1 2到18GHz腔基螺旋天線

圖2 腔基螺旋天線電磁仿真

圖3 腔基螺旋天線典型輻射圖樣

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本ben例li中zhong使shi用yong的de螺luo旋xuan輻fu射she結jie構gou非fei常chang適shi於yu此ci種zhong工gong作zuo模mo式shi，但dan是shi不bu再zai需xu要yao與yu帶dai有you吸xi收shou體ti的de腔qiang體ti連lian接jie使shi用yong。使shi用yong這zhe種zhong結jie構gou可ke以yi創chuang造zao兩liang種zhong類lei型xing的de天tian線xian：雙向結構，這種結構允許螺旋天線自由地向空間中其平麵法線的兩個方向輻射
；或增益更高的單向結構，這種結構中反射極緊靠螺旋天線使一個方向的輻射被反射回來，因此使前向增益增強。圖4給出了一個雙向螺旋天線。注意到其獨有特征可以擴展頻率覆蓋範圍。圖5給出某同類型天線的電磁仿真。圖6給出類似這種雙向螺旋天線的輻射特性。

圖4 雙向螺旋天線

圖5 雙向螺旋天線電磁仿真

圖6 雙向螺旋天線典型輻射圖樣

keyikandaodangjihuafangshizaiqianxiangweizuoshouyuanjihuashi，zaifanfangxiangweiyoushouyuanjihua。yinci，zaiqijiandechuanshuquyuzhongweixianxingjihua。zhezhongfangshizaixuduobushezhongjuyouyoushi。liru，ruguoyaozaizoulanghuodatingfangzhitianxian
，namezhezhongleixingdeshuangxiangtianxiankeyiwanmeidishihezhezhongqingkuang。youshi
，xuyaogengduofangxiangdetianxianerqiexubaochiqikuandaitexing。dianxingqingkuangweitianxianbuzhizaiqifugaifanweidejiaoluo，lirudatinghuozhongting。zhezhongqingkuangxia，fanshejiqidaozengjiaqianxiangzengyidezuoyong。tu7給出了這種單向小型螺旋天線的輻射圖樣。根據螺旋尺寸選擇

，可能提供400MHz到6GHz頻段上的覆蓋範圍。這些天線應用係統，無論原先安裝的時候還是將來，都要求收發通信頻帶使用單一天線。

圖7 單向螺旋天線典型輻射圖樣

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雙錐型天線

雙(shuang)錐(zhui)型(xing)天(tian)線(xian)被(bei)設(she)計(ji)用(yong)來(lai)在(zai)大(da)頻(pin)率(lv)範(fan)圍(wei)內(nei)有(you)效(xiao)地(di)工(gong)作(zuo)。這(zhe)種(zhong)天(tian)線(xian)產(chan)生(sheng)線(xian)性(xing)極(ji)化(hua)信(xin)號(hao)同(tong)時(shi)表(biao)現(xian)出(chu)極(ji)低(di)的(de)方(fang)位(wei)角(jiao)波(bo)動(dong)，這(zhe)意(yi)味(wei)著(zhe)其(qi)多(duo)方(fang)向(xiang)特(te)征(zheng)優(you)秀(xiu)。這(zhe)種(zhong)結(jie)構(gou)的(de)有(you)效(xiao)帶(dai)寬(kuan)處(chu)於(yu)兩(liang)倍(bei)頻(pin)程(cheng)間(jian)
，取(qu)決(jue)於(yu)可(ke)以(yi)容(rong)忍(ren)的(de)輸(shu)入(ru)反(fan)射(she)損(sun)耗(hao)。輸(shu)入(ru)反(fan)射(she)損(sun)耗(hao)的(de)影(ying)響(xiang)受(shou)此(ci)結(jie)構(gou)小(xiao)型(xing)化(hua)程(cheng)度(du)決(jue)定(ding)，小(xiao)型(xing)化(hua)的(de)原(yuan)因(yin)是(shi)選(xuan)擇(ze)了(le)圓(yuan)錐(zhui)到(dao)圓(yuan)柱(zhu)的(de)傳(chuan)輸(shu)區(qu)間(jian)
，或(huo)完(wan)全(quan)使(shi)用(yong)圓(yuan)錐(zhui)區(qu)間(jian)。圖(tu)8和圖9分別給出了某雙錐天線及其電磁仿真結果。圖10給(gei)出(chu)了(le)其(qi)測(ce)試(shi)性(xing)能(neng)，可(ke)以(yi)清(qing)晰(xi)地(di)看(kan)到(dao)其(qi)方(fang)向(xiang)角(jiao)圖(tu)樣(yang)波(bo)動(dong)非(fei)常(chang)小(xiao)。雖(sui)然(ran)在(zai)商(shang)業(ye)通(tong)信(xin)係(xi)統(tong)中(zhong)，這(zhe)些(xie)構(gou)造(zao)的(de)高(gao)功(gong)率(lv)處(chu)理(li)能(neng)力(li)並(bing)不(bu)總(zong)是(shi)很(hen)重(zhong)要(yao)
，但(dan)小(xiao)巧(qiao)的(de)尺(chi)寸(cun)卻(que)使(shi)其(qi)充(chong)滿(man)吸(xi)引(yin)力(li)。例(li)如(ru)一(yi)種(zhong)能(neng)覆(fu)蓋(gai)整(zheng)個(ge)從(cong)800MHz到2.2GHz頻段的產品可以封裝在一個直徑32mm
，長225mmdejiegouzhong。suirankeyihuodegengkuandedaikuan，danbixuzaidaikuanhezhijingshangzhezhongxuanze。jiaodadezhijinghuizhankuantianxiangongzuopinlv。zhexietianxiangouzaozaifeichangkuandepinlvfanweineibaochileqifushetuyangtexing

，shitamenshiheweixiaoquheweiweixiaoqudeyingyong。zheyangdexiaoquzhongshiyongtianxianfangdaxinhao（例如火車站）。擁有這種輻射圖樣的天線對於星形天線配置最有效。

圖8 雙錐型天線

圖9 雙錐型天線電磁仿真

圖10 雙錐型天線典型輻射圖樣

結論

對dui於yu現xian代dai通tong信xin網wang絡luo中zhong加jia入ru新xin頻pin段duan的de要yao求qiu不bu斷duan增zeng強qiang。當dang這zhe些xie新xin頻pin段duan出chu現xian在zai商shang業ye應ying用yong中zhong，就jiu需xu要yao升sheng級ji係xi統tong天tian線xian覆fu蓋gai這zhe些xie額e外wai頻pin段duan。如ru果guo現xian有you天tian線xian原yuan始shi設she計ji帶dai寬kuan不bu足zu
，那na麼me在zai更geng寬kuan的de頻pin率lv範fan圍wei內nei就jiu無wu法fa保bao持chi其qi性xing能neng。然ran而er，利li用yong原yuan本ben為wei軍jun事shi應ying用yong開kai發fa的de技ji術shu可ke以yi用yong傳chuan統tong螺luo旋xuan和he雙shuang錐zhui寬kuan帶dai天tian線xian結jie構gou設she計ji參can數shu設she計ji出chu滿man足zu上shang述shu要yao求qiu的de商shang業ye產chan品pin。