201212386 六、發明說明： 【發明所屬之技術領域】 本發明是有關於一種天線系統，特別是指一種高增益 且高指向性的多天線系統。 【先前技術】 由於目前的無線網路產品多以輕薄短小方便為訴求， 因此如何設計出符合使用需求的小型天線已成為目前無線 網路產品是否得以有效縮小體積的關鍵技術之一；尤其， J ^天線的„又计對於無線網路產品’例如：無線網路橋接 器（access point，AP)的訊號接收能力以及品質有著最直接 的關係，使得如何在無線網路產品有限的空間配置下，能 夠得到應有的天線性能表現，一直是相關產業首要解決的 課題。 然而，目前無線網路橋接器中所使用的天線大都為三 維（3-D)立體式的結構，如中華民國專利第M377714號所揭 露的夕輸入多輸出之雙頻單極天線（monopole antenna)裝 置」，但此類的天線會佔據較大的空間且需要連接一天線接 地面使得無線網路橋接器中可使用的空間受限。另外， 傳統3-D立體式金屬結構之天線設計，其天線輻射單元製 作需經多次彎折，在工序上較為繁瑣，且製造成本也較 高。此外，即使另改用短路單極天線或是倒F型天線 (Planar Inverted_F Antenna，PIFA)，其天線在 24GHz 及 5GHz的頻帶時最大增益卻分別只有3及相出，且天線輻射 場型並非垂向輻射（broadside radiati〇n)，並無法滿足高增益 201212386 及高指向性之需求。 【發明内容】 因此，本發明之目的，即在提供一種可達到雙頻操作 且具有高指向性及高增益的多天線系統。 本發明之另一目的，即在提供一種體積小、成本低、 低姿勢（l〇W-pn)file)的，且可應用在小型室外用無線網路橋 接器之内藏式雙頻多天線系統，以保持產品整體外觀的完 整性與美感度。 • 於是，本發明多天線系統，包含一天線模組及一系統 模組。天線模組包括一天線基板及多數個平面偶極天線， 天線基板包括一第一表面和一相反於該第一表面的第二表 面；該等平面偶極天線佈設於天線基板的第一表面上，且 每個平面偶極天線皆包括一具有一接地端的短路段、二可 提供一第一操作頻帶的第一輻射臂，及二可提供一第二操 作頻帶的第二輻射臂，該等第一輻射臂分別連接於短路段 的兩端，該等第二輻射臂分別4有一連接於短路段的饋入 _ & ’及-由饋人段末端延伸的延伸段，料第：輕射臂其 中之具有一饋入端，各該平面偶極天線的饋入端、接地 端與該等平面偶極天線共同界定出的幾何中心位於同一直 線，=該平面偶極天線的幾何中心與該等平面偶極天線共 同界定出的幾何中心的距離相同，且任二相鄰平面偶極天 線之間的最短距離相同，如此對稱式結構（symmetricai S^UCtUre)的天線’使其保有相同的隔離度（isolation) ’且讓 每一個平面偶極天線在空間中具有更對稱的訊號覆蓋空 5 201212386 間。 系統模組包括至少一相向於天線基板之第二表面的接 地面，且系統模組與天線基板之第二表面平行相間隔一距 離，該接地面係提供系、統電路板上射頻電路之系統接地 面，並用以反射該等平面偶極天線的輻射，使天線模組具 有高度的指向性，且提升天線模組在單一方向的天線增 益。 較佳地，各該平面偶極天線的二第一輻射臂分別連接 於短路段的兩端且平行於短路段的延伸方向（γ軸方向）背向 延伸，且二第二輻射臂分別具有一連接於短路段的饋入 段，及一連接於饋入段末端且平行於短路段的延伸方向延 伸的延伸段，饋入端位於該等饋入段其中之一上。 較佳地’天線基板還包括一位於該等平面偶極天線共 同界定出的幾何t心的穿孔，用以供多數個訊號傳輸線通 過’且配合每個平面偶極天線的饋入端及接地端與該等平 面偶極天線共同界定出的幾何中心的連線垂直於短路段的 延伸方向，如此當訊號傳輸線通過穿孔而電連接平面偶極 天線時’訊號傳輸線的延伸方向會與平面偶極天線的短路 段的延伸方向相互垂直（呈正交），以避免訊號傳輸線壓到平 面偶極天線而導致天線訊號與系統電路干擾的問題。 較佳地’天線基板的面積小於或等於系統模組的面 積’以確保系統模組能完全反射每個平面偶極天線的輻 射。 本發明提供一種具有多天線系統的電子裝置，包含一 201212386 殼體、一天線模組及一系統模組，天線模組裝設於殼體 中，且包括一天線基板及多數個平面偶極天線，天線基板 包括一第一表面和一相反於第一表面的第二表面；該等平 面偶極天線佈設於天線基板的第一表面上，且每個平面偶 極天線包括一具有一接地端的短路段、二可提供一第一操 作頻帶的第一輻射臂’及二可提供一第二操作頻帶的第二 輻射臂，該等第一輻射臂分別連接於短路段的兩端，該等 第二輻射臂分別具有一連接於短路段的饋入段，及一由饋 入段的末端延伸的延伸段，該等第二輻射臂其中之一具有 一饋入端，各該平面偶極天線的饋入端、接地端與該等平 面偶極天線共同界定出的幾何中心位於同一直線，各該平 面偶極天線的幾何中心與該等平面偶極天線共同界定出的 幾何中心的距離相同，且二相鄰平面偶極天線之間的最短 距離相同；系統模組裝設於殼體中，且包括至少一相向於 天線基板之第二表面的接地面，且系統模組與天線基板之 第二表面平行相間隔一距離，用以反射該等平面偶極天線 的輻射。 本發明之功效一在於，在天線基板上佈設多數個平面 偶極天線’來達到接收或發射多個不同頻段的訊號，且透 過系統模組上的至少一接地面來反射平面偶極天線的輻 射，可使天線模組的輻射場型具有高指向性及高天線增益 的特性，可提升通訊涵蓋範圍和傳輸距離。 本發明之功效二在於，多天線系統中各個平面偶極天 線的幾何中心與該等平面偶極天線共同界^的幾何中心之 201212386 間的距離相同，以及任二相鄰平面偶極天線的最短距離相 同，使各個平面偶極天線之間具有相同的隔離度及相同的 輻射場型與訊號覆蓋範圍。 本發明之功效三在於，平面偶極天線係使用印刷式電 路板製作，製作簡單且成本低，並具有低姿勢（low pr〇file) 的外型與平面式（planar)的結構，非常適合應用在小型室外 用的無線網路橋接器上。 【實施方式】 有關本發明之前述及其他技術内容、特點與功效，在 以下配合參考圖式之一個較佳實施例的詳細說明中，將可 清楚的呈現。 參閱圖1，為本發明多天線系統i 00之較佳實施例，其 為可操作在雙頻無線區域網路WLAN(2400-2484/5150- 5350MHz)的2 ,維平面式（2-d planer)雙頻乡天線系統（duai_ band mUlti_antenna system)1〇〇，而該2維平面式雙頻偶極天 線可採用印刷電路板製作，將雙頻偶極天線設計印製於印 刷電路板的的同-側上，如此設計可大幅降低成本。在本 實施例中，多天線系統i 〇〇包含一天線模組1 〇及一與天線 模組10平行間隔設置的系統模組20。 天線模組10包括一天線基板（substrate)〗及多數個平面 偶極天、線2。天線基板1(或稱介質基板）可為圓形或是任意 的多邊形，且係由絕緣材質（例如：玻璃纖維，fr4)所製 成。其中，該天線基板i具有一第一表面u、一相反於該 第表面11的第二表面12及一可供多數個訊號傳輸線6通 201212386 過的穿孔13。 配合參閱圖2 ’在本實施例中，平面偶極天線2係為半 波長雙頻偶極天線，且其數量為三，但天線數量與種類並 不以此為限。該等平面偶極天線2佈設於天線基板1的該 第表面11上，且每一個平面偶極天線2皆包括一短路段 3、二可提供一第一操作頻帶的第一輻射臂4,及二可提供 一第二操作頻帶的第二輻射臂5。其中，第一輻射臂4的長 度長於第二輻射臂5，以本實施例為例，第一輻射臂4的第 -操作頻帶為低頻2.4 GHz，而第二輻射臂5的第二操作頻 帶為高頻5 GHz。 短路#又3具有—接地端（gr〇und p〇int)3i ;二第一輻射 # 4刀別連接於短路段3的兩相反端且平行於短路段3的 延伸方向（即Y軸方向）背向延伸；各該第二輻射臂5具有一 連接於短路段3㈣人段51，及—連接於鎖人段51末端且 平订於紐路段3的延伸方向（即γ軸方向）延伸的延伸段 52，二第一輻射臂4及二第二輻射臂5共用該饋入段5ι。 在兩饋入段51之間間隔—第—饋人間隙（_卿)32。在兩 饋入段51其中之_上具有__饋入端（feed pQint)53，饋入端 53與接地端31相對且之間間隔一第二饋入間隙33，且第 一饋入間隙32與第二饋入間隙33連通。 藉由在天線基板1上佈設多數個平面偶極天線2，來達 到接收或發射多個不同頻段的訊號，並利用調整平面偶極 天線2的第二饋入間隙33及短路段3，改善電抗值，使其 電谷性與電感性電抗兩者能夠平衡，以達成天線良好的阻 201212386 抗頻寬（impedance bandwidth)，在2.4/5GHz無線區域網路 頻帶内得到優良的阻抗匹配（10_dB返回損失定義或2:1_ VSWR)。 在本實施例中，第二輻射臂5的延伸段52遠離連接饋 入段51的一端的寬度會大於鄰近連接饋入段51的一端的 寬度，使延伸段52約呈梯形，以換取更大的操作頻帶，但 延伸段52的形狀並不以本實施例為限，也可以為矩形如 圖3所不之梯形，或如圖4所示之等腰三角形（領結形）或水 滴形等。此外，請參閱圖5 ,饋入端53也可以位於另一個 饋入·^又5 1上，只要第一饋入間隙3 3及接地端31相對於饋鲁 入端53平移，使饋入端53、接地端31及三個平面偶極天 線2共同所界定出的幾何中心可位於同一直線上即可（請同 時參考圖6) <» 值得一提的是，圖2中平面偶極天線2的短路段3係 沿X軸方向凸出於二第一輻射臂4，而圖3〜圖5中短路段3 的一側邊係與二第一輻射臂4的一側邊位於同一直線上， 兩種實施方式的差異僅在於圖3〜圖5中的二第一輻射臂4 臂長會拉長（達到同樣是共振波& 1/2λ)，但均可以達成良籲 好阻抗頻寬及纟2.4/5GHz無線區域網路頻帶内得到優良的 阻抗匹配之特性’並不以本實施例為限。 參閱圖6，本實施例之平面偶極天線2的數量為三，該 些平面偶極天線2係沿著圓形天線基板1的圓周對稱分 佈’使每個平面偶極天線2的幾何中心與三個平面偶極天 線2 /、同所界定出的幾何中心（即a點）的距離相同即 10 201212386 咖❿，且任兩相鄰的平面偶極天線2之間的最短距離 皆相同，即L1=L2=L3,任兩相鄰的平面偶極天線2的幾何 中心分別與三個平面偶極天線2共同所界定出的幾何中 即A點）之間的連線所央角度亦相同，_ = ”也就是 夾12〇角。如此對稱式結構（symmetdcal structure)的天線疋 能防止平面偶極天線2之間的輕合（mutual c〇upH㈣使其 保有相同的隔離度（isolati⑽），且讓每_個平面偶極天線2 在空間中具有更對稱且均等的訊號覆蓋範圍。 • 參閱圖1、® 2及圖6 ’特別說明的是，天線基板上的 穿孔13係位於三個平面偶極天線2所共同界定出的幾何中 心，且每一個平面偶極天線2中的饋入端53與接地端31， 以及三個平面偶極天線2共同所界定出的幾何中心係位於 同一直線上（如圖6) ’且該直線係垂直於該短路段的延伸方 向。如此，當訊號傳輸線6電連接平面偶極天線2的饋入 端53與接地端31而通過穿孔13將該些平面偶極天線2所 接收到的天線訊號傳遞至無線寬頻路由器（r〇uter)或集線器 隹 （hub)内的電路板（圖未示）時，訊號傳輸線6的延伸方向會與 平面偶極天線2的短路段3的延伸方向（即γ軸方向）相互垂 直（呈正交），以避免訊號傳輸線6壓到平面偶極天線2的第 輻射臂4及第二輻射臂5而導致天線訊號與系統電路干 擾的問題發生。 系統模組20係為一系統電路板，其可為圓形或是任意 的多邊形。系統模組20具有至少一相向於天線基板丨之第 一表面12的接地面201 (例如··金屬面），該接地面2〇 1除了 201212386 作為系統電路板上射頻電路之系統接地面外，亦可視為一 反射板（reflector) ’用以反射該等平面偶極天線2的輻射， 藉此不但可使天線模、组10具有高度的指向性外，也可以提 升天線模組10在單一方向（即天線基板丨的第一表面u的 法線方向）的天線增益。其中，系統模組2〇可為多層結構， 最上層是薄的金屬層，下層則是介質基板，或者可以是包 含更多層的電路層。又，接地面（又可做為一反射面）2〇1與 第二表面12間存在一間距，作為系統模組2〇上電子元件（ 圖未示）擺設之有效空間利用。此外，本實施例之天線基板 1的面積小於或等於系統模組20的面積，以確保系統模組· 20能完全反射每個平面偶極天線2的輻射。 此外，參閱圖7，本實施例之多天線系統1〇〇係裝設於 如室外的無線網路橋接器（access point，AP)等電子裝置200 的一殼體210中’且藉由小型同軸線（mini_c〇axjai cable)作 為訊號傳輸線6，將訊號饋入平面偶極天線2的饋入端 53 ’使得多天線系統1 〇〇可配合不同應用的系統模組2〇(即 系統電路板）’提高多天線系統100使用上的彈性。當然， 訊號傳輸線6的種類並不因本實施例而受限制。 參閱圖8至圖10，為本實施例之多天線系統1 〇〇的實 際尺寸示意圖，其中圖8為多天線系統100的俯視圖；圖9 為單一平面偶極天線2的平面展開圖；圖10為天線模組1〇 與系統模組20之間的側視圖，各圖中數字的單位為公厘 (mm)，可參閱圖中各項數據以得知本實施例的實際規格尺 寸，但不以本實施例為限。 12 201212386 參閱圖8及圖l〇，本實施例之平面偶極天線2的總面 積為13.5x36.5麵2，且第一輻射n 4與第二輕射體5可分別 共振出2.4GHz及5GHz的頻帶。此外，天線基板丨與系統 模組20的間距介於5〜1 〇mm，如此多天線系統！ 〇〇具有低 姿態（l〇w-profile)的疊構形式，且可提供更多種類的電子元 件置放於系統模組20上，使得整個電子裝置2〇〇(圖7)内部 空間配置能有效利用，而本實施例之間距為1〇公厘（mm)將 獲得較佳的天線增益，且延伸段52與第一輻射臂4之間的 距離較佳介於0.5〜1.5mm之間。特別說明的是，平面偶極 天線2的厚度及系統模組2〇上金屬厚度（約為〇〇35公厘） 均遠小於天線基板1及系統模組2〇的厚度，故圖1〇中省 略不畫。 參閱圖1!，為各個平面偶極天線2的反射係數 (ReflectionCoefficient)量測數據圖，為了方便說明，配合參 閱圖6,以下將三個平面偶極天線2分別定義為一第一平面 偶極天線21、一第二平面偶極天線22及一第三平面偶極天 線23。而在圖u中，Sii、S2^ &分別為第一平面偶極 天線21、第二平面偶極天線22及第三平面偶極天線23的 反射係數。經實驗可得知，第一輻射體4提供的第一操作 頻帶的中心頻率為2.4GHz’第二輻射體5提供的第二操作 頻帶的中心頻率為5GHz，且兩者分別在24GHz及5〇Ηζ 的反射係數皆小於負l〇_dB，符合2.4GHz及5GHz無線區 域網路頻帶的規範，因此本實施例的確是可應用在無線區 域網路中。 13 201212386 參閱圖12，為各個平面偶極天線2之間的隔離度 (Isolation)量測數據圖，其中Sai為第一平面偶極天線21與 第二平面偶極天線22之間的隔離度；Ssi為第一平面偶極天 線21與第三平面偶極天線23之間的隔離度；為第二平 面偶極天線22與第三平面偶極天線23之間的隔離度。經 實驗可得知，各個平面偶極天線2之間的隔離度分別在 2.4GHz和5GHz頻帶低於負2〇_dB和負3〇 dB以下，具有 良好的隔離度。 參閱圖13及圖14，圖π為多天線系統1〇〇工作在頻 率2400MHz、2442MHz及2484MHz時的3_D輻射場型圖； 圖14則為多天線系統1〇〇工作在頻率515〇MHz、 及5825MHz的3-D輻射場型圖。由圖13及圖14可知，藉 由天線模組10與系統模組2〇的相互配合，使得多天線系 統100在正z軸方向具有較高的天線增益，即高度的指向 性，可適用於無線網路橋接器（AP)。 圖15為本實施例之多天線系統100的輻射效率 (radiation efficiency)/天線增益_頻率曲線圖。由圖可知在 2.4 GHz與5 GHz頻帶内天線最大增益皆在6犯丨以上，具 有南天線增益的特性。天線的輻射效率亦皆在6〇%以上， 為良好的印刷式天線效率。 參閱圖1’特別說明的是，本實施例之多天線系統1〇〇 係藉由系統模組20反射平面偶極天線2的輻射，而不需像 傳統3-D立體式結構金屬片天線設計要額外連接一天線接 地面’就能使得天線輻射場型具有較高指向性，且多天線 14 201212386 糸統100分別操作在2.4G及5GHz頻帶時，半功率束徑寬 (Half-Power Bandwidth，HPBW)可高達 990 及 106°，以及具 有良好的極化分1則後比（fr〇nt-to-back ratio)，頻帶内最高 可達20 dB ’以達成高增益天線的設計。 综上所述，本發明多天線系統1〇〇的功效如下： 1.藉由在天線基板1上佈設多數個平面偶極天線2， 來達到接收或發射多個不同頻段的訊號，並利用調 整平面偶極天線2的第二饋入間隙33及短路段 • 3，可以改善電抗值，使平面偶極天線2的電容性 與電感性能夠平衡，以達成天線良好的阻抗頻寬 (impedance bandwidth)，在 2.4/5GHz 無線區域網路 頻帶内得到優良的阻抗匹配。 2'多天線系統100中各個平面偶極天線2的幾何中心 與該等平面偶極天線2共同界定的幾何中心之間的 距離相同’以及任二相鄰平面偶極天線2的最短距 離相同’使各個平面偶極天線2之間具有相同的隔 鲁離度及相同的輻射場型與訊號覆蓋範圍。各個平面 偶極天線2中的饋人端53與接地端31，以及三個 平面偶極天線2共同所界定出的幾何中心係位於同 -直線上，使得減傳輸線6 f連接平面偶極天線 2時’訊號傳輸線6的延伸方向會與平面偶極天線 2的短路段3的延伸方向相互垂直(呈正交)，如此 將可使訊號傳輸線6長度為最短，且可避免訊號傳 輸線6壓到平面偶極天線2而導致天線訊號與系統 15 201212386 電:干擾的問題。透過天線模組1〇與系統模組2〇 整口，並藉由該系統模組2〇上的至少一接地面來 反射平面偶極天線2的輻射’不但可使天線模組 10具有尚度的指向性，也可以提升天線模組1〇在 單方向（正2軸方向）的天線增益，故確實能達成 本發明之目的。 准X上所述者，僅為本發明之較佳實施例而已，當不 色、此限疋本發明實施之範圍，即大凡依本發明申請專利 範圍及發明說明内容所作之簡單的等效變化與修飾皆仍 屬本發明專利涵蓋之範圍内。 鲁 【圖式簡單說明】 圖1是說明本發明多天線系統的較佳實施例； 圖2是說明本實施例中單一平面偶極天線的平面展開 圖； 圖3是說明本實施例中單一平面偶極天線的另一種變 化態樣； 圖4是說明本實施例中單一平面偶極天線的另一種變 化態樣； ® 圖5是說明本實施例中單一平面偶極天線的另一種變 化態樣； 圖6是說明本實施例中多天線系統的平面展開圖； 圖7是說明内藏式多天線系統的電子裝置； 圖8是說明本實施例中各個平面偶極天線之間的實際 規格尺寸； 16 201212386 圖 尺寸， 9是說明本實 施例十單一平面偶極天線的實際規格 一 &%明本實施例中天線模組與系統模組之間的實 際規格尺寸； 疋說明本實施例中各個平面偶極天線的反射係數 量測數據圖； 圖】2是說明本實施例中各個平面偶極天線彼此之間的 隔離度量測數據圖；201212386 VI. Description of the Invention: [Technical Field] The present invention relates to an antenna system, and more particularly to a multi-antenna system with high gain and high directivity. [Prior Art] Since the current wireless network products are mostly demanding in terms of lightness, shortness and convenience, how to design a small antenna that meets the needs of use has become one of the key technologies for wireless network products to effectively reduce the size; in particular, J ^The antenna has the most direct relationship to the wireless network products, such as the wireless network bridge (access point, AP) signal receiving capability and quality, so that in the limited space configuration of wireless network products, It is always the primary problem to be solved in the related industries. However, most of the antennas used in wireless network bridges are three-dimensional (3-D) stereoscopic structures, such as the Republic of China Patent No. M377714. The dual-frequency monopole antenna device disclosed in the present invention, but such an antenna occupies a large space and needs to be connected to an antenna ground plane to make available space in the wireless network bridge. Limited. In addition, the antenna design of the conventional 3-D three-dimensional metal structure requires a plurality of bending of the antenna radiating element, which is cumbersome in the process and high in manufacturing cost. In addition, even if the short-circuit monopole antenna or the inverted F-type antenna (Planar Inverted_F Antenna, PIFA) is used, the maximum gain of the antenna in the 24 GHz and 5 GHz bands is only 3 and phase out, and the antenna radiation field is not vertical. Radiation (broadside radiati〇n) does not meet the high gain 201212386 and high directivity requirements. SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a multi-antenna system that achieves dual frequency operation and has high directivity and high gain. Another object of the present invention is to provide a built-in dual-frequency multi-antenna with small size, low cost, low posture (l〇W-pn) file, and can be applied to a small outdoor wireless network bridge. System to maintain the integrity and aesthetics of the overall appearance of the product. • Thus, the multi-antenna system of the present invention comprises an antenna module and a system module. The antenna module includes an antenna substrate and a plurality of planar dipole antennas. The antenna substrate includes a first surface and a second surface opposite to the first surface. The planar dipole antennas are disposed on the first surface of the antenna substrate. And each of the planar dipole antennas includes a shorting section having a grounding end, a first radiating arm that provides a first operating frequency band, and a second radiating arm that provides a second operating frequency band. A radiating arm is respectively connected to both ends of the short-circuiting section, and the second radiating arms respectively have a feeding _ & ' connected to the short-circuited section and an extension extending from the end of the feeding section, the material: the light arm The feed end and the ground end of each of the planar dipole antennas are in the same straight line as the geometric center defined by the planar dipole antennas, = the geometric center of the planar dipole antenna and the same The planar dipole antennas have the same geometric center defined distance, and the shortest distance between any two adjacent planar dipole antennas is the same, so the symmetrically symmetrical structure (symmetricai S^UCtUre) antenna keeps it The same degree of isolation (isolation) 'and so that each plane has a more symmetrical dipole antenna cover used 5 201,212,386 signal in space. The system module includes at least one ground plane facing the second surface of the antenna substrate, and the system module is spaced apart from the second surface of the antenna substrate by a distance, and the ground plane provides a system for the RF circuit of the system and the circuit board. The ground plane is used to reflect the radiation of the planar dipole antennas, so that the antenna module has a high directivity and enhances the antenna gain of the antenna module in a single direction. Preferably, the two first radiating arms of each of the planar dipole antennas are respectively connected to both ends of the short-circuiting section and extend away from the extending direction (γ-axis direction) of the short-circuiting section, and the two second radiating arms respectively have one a feed section connected to the short-circuit section, and an extension connected to the end of the feed section and extending parallel to the extension direction of the short-circuit section, the feed end being located on one of the feed sections. Preferably, the antenna substrate further includes a geometrical t-hole defined by the planar dipole antennas for passing through a plurality of signal transmission lines and matching the feeding end and the grounding end of each planar dipole antenna. The line connecting the geometric center defined by the planar dipole antennas is perpendicular to the extending direction of the short-circuited section, so that when the signal transmission line is electrically connected to the planar dipole antenna through the perforation, the extension direction of the signal transmission line and the planar dipole antenna The extension direction of the short-circuited sections is perpendicular to each other (orthogonal) to avoid the problem that the signal transmission line is pressed to the planar dipole antenna and the antenna signal interferes with the system circuit. Preferably, the area of the antenna substrate is less than or equal to the area of the system module to ensure that the system module fully reflects the radiation of each planar dipole antenna. The invention provides an electronic device with a multi-antenna system, comprising a 201212386 housing, an antenna module and a system module. The antenna module is assembled in the housing and comprises an antenna substrate and a plurality of planar dipole antennas. The antenna substrate includes a first surface and a second surface opposite to the first surface; the planar dipole antennas are disposed on the first surface of the antenna substrate, and each of the planar dipole antennas includes a short having a ground end The first radiating arm of the first operational frequency band and the second radiating arm of the second operational frequency band, wherein the first radiating arms are respectively connected to the two ends of the short-circuiting section, the second The radiating arms respectively have a feeding section connected to the short-circuiting section, and an extending section extending from the end of the feeding section, one of the second radiating arms has a feeding end, and the feeding of each of the planar dipole antennas The geometric center defined by the input end and the ground end and the planar dipole antennas are in the same straight line, and the geometric center of each of the planar dipole antennas and the geometrical plane defined by the planar dipole antennas The distance is the same, and the shortest distance between two adjacent planar dipole antennas is the same; the system module is assembled in the housing and includes at least one ground plane facing the second surface of the antenna substrate, and the system module and The second surfaces of the antenna substrate are spaced apart by a distance parallel to reflect the radiation of the planar dipole antennas. One of the effects of the present invention is that a plurality of planar dipole antennas are disposed on the antenna substrate to receive or transmit signals of different frequency bands, and the radiation of the planar dipole antenna is reflected through at least one ground plane on the system module. The radiation pattern of the antenna module can be characterized by high directivity and high antenna gain, which can improve communication coverage and transmission distance. The second effect of the present invention is that the geometric center of each planar dipole antenna in the multi-antenna system is the same as the distance between the geometric centers of the planar dipole antennas 201212386, and the shortest of any two adjacent planar dipole antennas. The distance is the same, so that each planar dipole antenna has the same isolation and the same radiation field and signal coverage. The third effect of the present invention is that the planar dipole antenna is fabricated using a printed circuit board, is simple to manufacture and low in cost, and has a low pr file appearance and a planar structure, which is very suitable for application. On a small outdoor wireless network bridge. The above and other technical contents, features, and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments. Referring to FIG. 1, a preferred embodiment of a multi-antenna system i 00 of the present invention is a 2-dimensional plane (2-d planer) operable in a dual-band wireless local area network WLAN (2400-2484/5150-5350 MHz). The dual-band mUlti_antenna system is one-inch, and the 2-dimensional planar dual-frequency dipole antenna can be fabricated by using a printed circuit board, and the dual-frequency dipole antenna design is printed on the printed circuit board. - On the side, this design can significantly reduce costs. In this embodiment, the multi-antenna system i 〇〇 includes an antenna module 1 and a system module 20 disposed in parallel with the antenna module 10. The antenna module 10 includes an antenna substrate and a plurality of planar dipole days and lines 2. The antenna substrate 1 (or dielectric substrate) may be circular or of any polygonal shape and made of an insulating material (for example, glass fiber, fr4). The antenna substrate i has a first surface u, a second surface 12 opposite to the first surface 11, and a through hole 13 through which the plurality of signal transmission lines 6 pass 201212386. Referring to FIG. 2', in the present embodiment, the planar dipole antenna 2 is a half-wavelength dual-frequency dipole antenna, and the number thereof is three, but the number and type of antennas are not limited thereto. The planar dipole antennas 2 are disposed on the first surface 11 of the antenna substrate 1, and each of the planar dipole antennas 2 includes a shorting section 3, a first radiating arm 4 that provides a first operating frequency band, and Second, a second radiating arm 5 of a second operating frequency band can be provided. Wherein, the length of the first radiating arm 4 is longer than that of the second radiating arm 5. In the embodiment, the first operating band of the first radiating arm 4 is a low frequency of 2.4 GHz, and the second operating band of the second radiating arm 5 is High frequency 5 GHz. The short circuit #3 has a grounding end (gr〇und p〇int) 3i; the second first radiation #4 is connected to the opposite ends of the short-circuiting section 3 and parallel to the extending direction of the short-circuiting section 3 (ie, the Y-axis direction) Each of the second radiating arms 5 has a connecting portion 51 connected to the short-circuiting section 3 (four), and an extension extending to the end of the locking section 51 and being aligned in the extending direction of the new section 3 (ie, the γ-axis direction) The segment 52, the two first radiating arms 4 and the two second radiating arms 5 share the feeding segment 5ι. Between the two feed segments 51, the first-feeder gap (_clear) 32. There is a __feed pQint 53 on the _ of the two feed segments 51, and the feed end 53 is opposite to the ground end 31 with a second feed gap 33 therebetween, and the first feed gap 32 It is in communication with the second feed gap 33. By arranging a plurality of planar dipole antennas 2 on the antenna substrate 1 to receive or transmit signals of a plurality of different frequency bands, and adjusting the second feeding gap 33 and the short-circuiting section 3 of the planar dipole antenna 2, the reactance is improved. The value makes it possible to balance both the electric valley and the inductive reactance to achieve a good resistance of the antenna 201212386 impedance bandwidth, and excellent impedance matching in the 2.4/5 GHz wireless local area network band (10_dB return loss) Definition or 2:1_ VSWR). In this embodiment, the width of the extension 52 of the second radiating arm 5 away from the end of the feeding feed section 51 is greater than the width of the end adjacent to the feeding section 51, so that the extension 52 is approximately trapezoidal in exchange for a larger The operating frequency band, but the shape of the extending portion 52 is not limited to the embodiment, and may be a trapezoidal shape as shown in FIG. 3, or an isosceles triangle (bow tie shape) or a teardrop shape as shown in FIG. In addition, referring to FIG. 5, the feed end 53 may also be located on another feed port, and the feed end is translated as long as the first feed gap 3 3 and the ground end 31 are translated relative to the feed end 53. 53. The geometric center defined by the grounding end 31 and the three planar dipole antennas 2 can be located on the same straight line (please refer to FIG. 6 at the same time) <» It is worth mentioning that the planar dipole antenna in Fig. 2 The short-circuiting section 3 of 2 protrudes from the first radiating arm 4 in the X-axis direction, and one side of the short-circuited section 3 in FIG. 3 to FIG. 5 is on the same line as one side of the two first radiating arms 4. The difference between the two embodiments is only that the arm lengths of the two first radiating arms 4 in FIG. 3 to FIG. 5 are elongated (up to the same resonant wave & 1/2 λ), but both can achieve good impedance bandwidth. And the excellent impedance matching characteristics in the 2.4/5 GHz wireless local area network band' is not limited to this embodiment. Referring to FIG. 6, the number of planar dipole antennas 2 of the present embodiment is three, and the planar dipole antennas 2 are symmetrically distributed along the circumference of the circular antenna substrate 1 to make the geometric center of each planar dipole antenna 2 The three planar dipole antennas 2 / have the same distance from the defined geometric center (ie point a), ie 10 201212386 curry, and the shortest distance between any two adjacent planar dipole antennas 2 is the same, ie L1=L2=L3, the angle between the geometric center of any two adjacent planar dipole antennas 2 and the geometry defined by the three planar dipole antennas 2, respectively, that is, point A) is also the same. _ = ” is the 12 corners. The symmetdcal structure of the antenna can prevent the light coupling between the planar dipole antennas 2 (mutual c〇upH (4) to maintain the same isolation (isolati (10)), and Let each _ planar dipole antenna 2 have a more symmetrical and equal signal coverage in space. • Refer to Figure 1, о 2 and Figure 6 'Specifically, the perforations 13 on the antenna substrate are located in three planes. The geometric center defined by the polar antenna 2, The feeding end 53 of each planar dipole antenna 2 is in line with the geometric center defined by the grounding end 31 and the three planar dipole antennas 2 (Fig. 6) 'and the straight line is perpendicular to The extending direction of the short-circuiting section is such that when the signal transmission line 6 is electrically connected to the feeding end 53 of the planar dipole antenna 2 and the grounding end 31, the antenna signals received by the planar dipole antennas 2 are transmitted to the wireless through the through-holes 13. When a circuit board (not shown) in a broadband router (r〇uter) or hub hub (not shown), the direction of extension of the signal transmission line 6 and the extension direction of the short-circuit section 3 of the planar dipole antenna 2 (ie, the γ-axis direction) They are perpendicular to each other (in an orthogonal manner) to prevent the signal transmission line 6 from being pressed to the radiating arm 4 and the second radiating arm 5 of the planar dipole antenna 2, thereby causing the problem that the antenna signal interferes with the system circuit. The system module 20 is one. The system board can be circular or arbitrarily polygonal. The system module 20 has at least one ground plane 201 (for example, a metal surface) facing the first surface 12 of the antenna substrate ,, the ground plane 2〇1 Except 201212386 As a system ground plane of the RF circuit on the system board, it can also be regarded as a reflector 'reflecting the radiation of the plane dipole antenna 2, thereby not only making the antenna module and the group 10 have a high degree of pointing. In addition, the antenna gain of the antenna module 10 in a single direction (ie, the normal direction of the first surface u of the antenna substrate )) can be improved. The system module 2 can be a multi-layer structure, and the uppermost layer is a thin metal. The layer, the lower layer is a dielectric substrate, or may be a circuit layer containing more layers. Moreover, the ground plane (which can also be used as a reflective surface) has a spacing between the second surface 12 and the second surface 12 as the system module 2 The effective space utilization of the electronic components (not shown). In addition, the area of the antenna substrate 1 of the present embodiment is less than or equal to the area of the system module 20 to ensure that the system module 20 can completely reflect the radiation of each planar dipole antenna 2. In addition, referring to FIG. 7, the multi-antenna system 1 of the present embodiment is installed in a housing 210 of an electronic device 200 such as an outdoor wireless access point (AP), and is supported by a small coaxial cable. The line (mini_c〇axjai cable) is used as the signal transmission line 6, and the signal is fed into the feeding end 53' of the planar dipole antenna 2 so that the multi-antenna system 1 can be matched with the system module 2 of different applications (ie, the system board) 'Improve the flexibility in the use of the multi-antenna system 100. Of course, the type of the signal transmission line 6 is not limited by this embodiment. 8 to FIG. 10 are schematic diagrams showing the actual size of the multi-antenna system 1 of the present embodiment, wherein FIG. 8 is a plan view of the multi-antenna system 100; FIG. 9 is a plan view of a single-plane dipole antenna 2; FIG. For the side view between the antenna module 1〇 and the system module 20, the unit of the number in each figure is mm (mm), refer to the data in the figure to know the actual size of the embodiment, but not This embodiment is limited. 12 201212386 Referring to FIG. 8 and FIG. 10, the total area of the planar dipole antenna 2 of the present embodiment is 13.5 x 36.5 face 2, and the first radiation n 4 and the second light emitter 5 can respectively resonate at 2.4 GHz and 5 GHz band. In addition, the distance between the antenna substrate 丨 and the system module 20 is between 5 and 1 〇 mm, so many antenna systems! 〇〇 has a low profile (l〇w-profile) stacked form, and can provide more kinds of electronic components placed on the system module 20, so that the entire electronic device 2 〇〇 (Fig. 7) internal space configuration can Effective use, while the distance between the embodiments is 1 mm (mm) will obtain a better antenna gain, and the distance between the extension 52 and the first radiating arm 4 is preferably between 0.5 and 1.5 mm. In particular, the thickness of the planar dipole antenna 2 and the thickness of the metal on the system module 2 (about 公35 mm) are much smaller than the thickness of the antenna substrate 1 and the system module 2〇, so Figure 1 Omit not to draw. Referring to FIG. 1!, the reflection coefficient of each planar dipole antenna 2 is measured. For convenience of description, referring to FIG. 6, the three planar dipole antennas 2 are respectively defined as a first planar dipole. The antenna 21, a second planar dipole antenna 22 and a third planar dipole antenna 23 are provided. In Fig. u, Sii, S2^ & are the reflection coefficients of the first planar dipole antenna 21, the second planar dipole antenna 22, and the third planar dipole antenna 23, respectively. It can be known through experiment that the center frequency of the first operating band provided by the first radiator 4 is 2.4 GHz. The center frequency of the second operating band provided by the second radiator 5 is 5 GHz, and the two are respectively at 24 GHz and 5 〇. The reflection coefficient of Ηζ is less than negative l〇_dB, which conforms to the specifications of 2.4 GHz and 5 GHz wireless local area network bands. Therefore, this embodiment can be applied to a wireless local area network. 13 201212386 Referring to FIG. 12, an isolation measurement data diagram between each planar dipole antenna 2, wherein Sai is an isolation between the first planar dipole antenna 21 and the second planar dipole antenna 22; Ssi is the isolation between the first planar dipole antenna 21 and the third planar dipole antenna 23; the isolation between the second planar dipole antenna 22 and the third planar dipole antenna 23. It can be known from experiments that the isolation between the planar dipole antennas 2 is lower than minus 2 〇 _dB and minus 3 〇 dB in the 2.4 GHz and 5 GHz bands, respectively, and has good isolation. Referring to FIG. 13 and FIG. 14, FIG. π is a 3D radiation pattern of a multi-antenna system operating at frequencies of 2400 MHz, 2442 MHz, and 2484 MHz; FIG. 14 is a multi-antenna system operating at a frequency of 515 〇 MHz, and 3-825 radiation field pattern of 5825MHz. It can be seen from FIG. 13 and FIG. 14 that the multi-antenna system 100 has a high antenna gain in the positive z-axis direction, that is, a high directivity, by the mutual cooperation of the antenna module 10 and the system module 2〇, which can be applied to Wireless network bridge (AP). Figure 15 is a graph showing the radiation efficiency/antenna gain_frequency of the multi-antenna system 100 of the present embodiment. It can be seen from the figure that the maximum gain of the antenna in the 2.4 GHz and 5 GHz bands is above 6 and has the characteristics of the south antenna gain. The radiation efficiency of the antenna is also above 6〇%, which is a good printed antenna efficiency. Referring to FIG. 1 ' in particular, the multi-antenna system 1 of the present embodiment reflects the radiation of the planar dipole antenna 2 by the system module 20, and does not need to be designed like a conventional 3-D stereo structure metal piece antenna. To additionally connect an antenna ground plane', the antenna radiation field type has high directivity, and the multi-antenna 14 201212386 system 100 operates in the 2.4G and 5GHz bands respectively, and the half-power band width (Half-Power Bandwidth, HPBW) can be as high as 990 and 106°, and has a good polarization ratio of 1 (fr〇nt-to-back ratio, up to 20 dB in the band) to achieve high gain antenna design. In summary, the multi-antenna system of the present invention has the following effects: 1. By arranging a plurality of planar dipole antennas 2 on the antenna substrate 1, signals for receiving or transmitting a plurality of different frequency bands are obtained, and adjustment is utilized. The second feeding gap 33 and the short-circuiting section 3 of the planar dipole antenna 2 can improve the reactance value and balance the capacitance and inductance of the planar dipole antenna 2 to achieve a good impedance bandwidth of the antenna. Excellent impedance matching in the 2.4/5 GHz wireless LAN band. The geometric center of each planar dipole antenna 2 in the 2' multi-antenna system 100 is the same as the geometric center defined by the planar dipole antennas 2 and the shortest distance of any two adjacent planar dipole antennas 2 is the same ' The same planar radiance and the same radiation pattern and signal coverage are provided between the respective planar dipole antennas 2. The geometric center defined by the feed end 53 and the ground end 31 of each planar dipole antenna 2 and the three planar dipole antennas 2 are located on the same line, so that the subtraction transmission line 6 f is connected to the planar dipole antenna 2 When the direction of the signal transmission line 6 is perpendicular to the extending direction of the short-circuited section 3 of the planar dipole antenna 2 (orthogonal), the length of the signal transmission line 6 can be minimized, and the signal transmission line 6 can be prevented from being pressed to the plane. Dipole antenna 2 causes antenna signal and system 15 201212386 electricity: interference problem. The antenna module 1 is connected to the system module 2, and the radiation of the planar dipole antenna 2 is reflected by at least one ground plane on the system module 2'. The directivity of the antenna module 1 can also increase the antenna gain of the antenna module 1 in the single direction (positive 2 axis direction), so that the object of the present invention can be achieved. The above is only the preferred embodiment of the present invention, and is not limited to the scope of the present invention, that is, the simple equivalent change of the patent application scope and the description of the invention according to the present invention. And modifications are still within the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view showing a preferred embodiment of a multi-antenna system according to the present invention; FIG. 2 is a plan view showing a single planar dipole antenna in the present embodiment; FIG. 3 is a view showing a single plane in this embodiment. Another variation of the dipole antenna; FIG. 4 is another variation of the single planar dipole antenna in the present embodiment; FIG. 5 is a diagram showing another variation of the single planar dipole antenna in this embodiment. Figure 6 is a plan view showing the planar configuration of the multi-antenna system of the present embodiment; Figure 7 is an electronic device for explaining the built-in multi-antenna system; Figure 8 is a view showing the actual size of the planar dipole antennas in this embodiment. 16 201212386 Figure size, 9 is the actual specification of the ten single planar dipole antenna of the present embodiment, and the actual size of the antenna module and the system module in the present embodiment; The reflection coefficient measurement data map of each planar dipole antenna; FIG. 2 is a diagram illustrating the isolation measurement data of each planar dipole antenna in the embodiment;
圖13是說明本實施例之多天線系統分別在頻率 2400MHz、2442MHz 及 2484MHz 的 3-D 輻射場型圖； 圖14是說明本實施例之多天線系統分別在頻率 5150MHz、5490MHz及5825MHz的3七轄射場型圖.及 圖15是說明本實施例之多天線系統的輻射效率/天線增 益-頻率曲線圖。FIG. 13 is a diagram showing a 3-D radiation pattern of the multi-antenna system of the present embodiment at frequencies of 2400 MHz, 2442 MHz, and 2484 MHz; FIG. 14 is a diagram showing the multi-antenna system of the present embodiment at three frequencies of 5150 MHz, 5490 MHz, and 5825 MHz, respectively. The field pattern is shown. Fig. 15 is a graph showing the radiation efficiency/antenna gain-frequency curve of the multi-antenna system of the present embodiment.
17 201212386 【主要元件符號說明】 100.......多天線系統 200 .......電子裝置 210.......殼體 10 .........天線模組 1 ..........天線基板 11 .........第一表面 12 .........第二表面 13 .........穿孔 2 ..........平面偶極天線 21 .........第一平面偶極天 線 22 .........第二平面偶極天 線 23 .........第三平面偶極天 線 3 ..........短路段 31 .........接地端 32 .........第一饋入間隙 33 .........第二饋入間隙 4 ..........第一輻射臂 5 ..........第二輻射臂 51 .........饋入段 52 .........延伸段 53 .........饋入端 6 ..........訊號傳輸線 20.........系統模組 201 .......接地面 1817 201212386 [Description of main component symbols] 100.......Multi-antenna system 200.......Electronic device 210.......Chassis 10 .........Antenna Module 1 ..... antenna substrate 11 ... first surface 12 ... ... second surface 13 ........ Perforation 2 ..... planar dipole antenna 21 ... first planar dipole antenna 22 ... ... second planar dipole antenna 23 .........the third planar dipole antenna 3 ..... short circuit segment 31 ......... ground terminal 32 ......... First feed gap 33 .... second feed gap 4 ..... first radiation arm 5 .......... second radiation arm 51 .........feeding section 52 .........extension section 53 .........feeding end 6 ..........signal Transmission line 20.........system module 201.......ground plane 18