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tu3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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benlizhongshiyongdeluoxuanfushejiegoufeichangshiyucizhonggongzuomoshi，danshibuzaixuyaoyudaiyouxishoutideqiangtilianjieshiyong。shiyongzhezhongjiegoukeyichuangzaoliangzhongleixingdetianxian：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

可(ke)以(yi)看(kan)到(dao)當(dang)極(ji)化(hua)方(fang)式(shi)在(zai)前(qian)向(xiang)為(wei)左(zuo)手(shou)圓(yuan)極(ji)化(hua)時(shi)，在(zai)反(fan)方(fang)向(xiang)為(wei)右(you)手(shou)圓(yuan)極(ji)化(hua)。因(yin)此(ci)，在(zai)其(qi)間(jian)的(de)傳(chuan)輸(shu)區(qu)域(yu)中(zhong)為(wei)線(xian)性(xing)極(ji)化(hua)。這(zhe)種(zhong)方(fang)式(shi)在(zai)許(xu)多(duo)布(bu)設(she)中(zhong)具(ju)有(you)優(you)勢(shi)。例(li)如(ru)，如(ru)果(guo)要(yao)在(zai)走(zou)廊(lang)或(huo)大(da)廳(ting)放(fang)置(zhi)天(tian)線(xian)，那(na)麼(me)這(zhe)種(zhong)類(lei)型(xing)的(de)雙(shuang)向(xiang)天(tian)線(xian)可(ke)以(yi)完(wan)美(mei)地(di)適(shi)合(he)這(zhe)種(zhong)情(qing)況(kuang)。有(you)時(shi)，需(xu)要(yao)更(geng)多(duo)方(fang)向(xiang)的(de)天(tian)線(xian)而(er)且(qie)需(xu)保(bao)持(chi)其(qi)寬(kuan)帶(dai)特(te)性(xing)。典(dian)型(xing)情(qing)況(kuang)為(wei)天(tian)線(xian)布(bu)置(zhi)在(zai)其(qi)覆(fu)蓋(gai)範(fan)圍(wei)的(de)角(jiao)落(luo)，例(li)如(ru)大(da)廳(ting)或(huo)中(zhong)庭(ting)。這(zhe)種(zhong)情(qing)況(kuang)下(xia)，反(fan)射(she)極(ji)起(qi)到(dao)增(zeng)加(jia)前(qian)向(xiang)增(zeng)益(yi)的(de)作(zuo)用(yong)。圖(tu)7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cong800MHz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

duiyuxiandaitongxinwangluozhongjiaruxinpinduandeyaoqiubuduanzengqiang。dangzhexiexinpinduanchuxianzaishangyeyingyongzhong
，jiuxuyaoshengjixitongtianxianfugaizhexieewaipinduan。ruguoxianyoutianxianyuanshishejidaikuanbuzu，namezaigengkuandepinlvfanweineijiuwufabaochiqixingneng。raner，liyongyuanbenweijunshiyingyongkaifadejishukeyiyongchuantongluoxuanheshuangzhuikuandaitianxianjiegoushejicanshushejichumanzushangshuyaoqiudeshangyechanpin。