200926521 九、發明說明： 【發明所屬之技術領域】 本發明是有關於一種圓極化天線，特別是# — ^ 種縮小 化之圓極化天線。 【先前技術】 隨著無線射頻辨識系統技術（RFID)應用的逐漸普及，使 得物件辨識更快速也更安全。且為方便使用者攜帶或使用 ，輕薄短小成為電子產品的主要設計趨勢，因此當圓極化 天線應用在該等電子產品上時，天線的尺寸大小成為設計 天線時的重要考量之一。 一般圓極化平面天線的設計可分為單饋入與雙饋入兩 種方式。單饋入之圓極化天線可利用截角、挖槽孔或植入 窄槽縫等微擾方式，使原本正交的模態激發出兩個等振幅 且相位差90度的相鄰垂直模態。但此種天線雖然只需單層 基板即可，但其缺點是操作頻寬非常狹窄，通常不超過其 線性極化輻射頻寬的三分之一，且設計限制條件較多，不 容易調整天線圓極化特性及阻抗匹配，所以設計困難。至 於雙饋入之圓極化天線則通常是使用Wilkinson功率分配器 或支路耦合器（branch-line coupler)來提供振幅相等且相位相 差90度的激發電流，且兩個饋入點需分別位於互相垂直的 方向。此種天線具有較單饋入之天線頻寬大且天線圓極化 特性良好等優點’但由於需要使用兩層以上的基板，以致 天線體積變得過於龐大。 【發明内容】 200926521 因此，本發明之目的，係在提供一種在不影響天線輻 射效能情況下有效縮小天線尺寸的圓極化天線。 於是，本發明之圓極化天線，包括一基板、一環形輻 射部、一微帶輻射部及一接地面。該基板具有相反之一第 一面及一第二面》該環形輻射部設於該基板之第一面。該 微帶輕射部設於該環形輻射部所圍繞的空間中，並包括一 第一線段及一第二線段，該二線段的一端相鄰近以饋入訊 號，另一端相遠離且分別連接該環形輻射部。該接地面， 設於該基板之第二面。 較佳地，該圓極化天線更包括一用以平均分配饋入訊 號功率的饋入單元，其包含設於該環形輻射部所圍繞的空 間中的一饋入部及一電阻，該饋入部包含一饋入線段及二 由該饋入線段一端向外延伸之轉阻線段，該二轉阻線段分 別終止於該第一線段及第二線段相鄰近的一端並各別連接 該第一線段及第二線段，且該電阻兩端連接該二轉阻線段 之鄰近該第一線段及第二線段的一端。 較佳地’其中該饋入線段的另一端更設有一貫穿該基 板的第一面和第二面的貫孔，供一 SMA接頭連接以饋入訊 號，以使該SMA接頭的中心饋入線與該饋入線段電連接， 並使該SMA接頭的一接地端經由該貫孔與設於基板第二面 的接地面電連接。 可替換地，該饋入單元可以是一功率分配器，其連接 該第一線段及第二線段相鄰近的一端，用以分配饋入訊號 功率使平均饋入該第一線段及第二線段。 6 200926521 角 較佳地，該環形輻射部可以是m環形、方環形、 環形或橢圓環形之環形結構金屬線。 較佳地，該第—線段及第二線段可以是L形彎折或圓 弧形之金屬線段，且第—線段及第二線段係概呈垂直地以 其相遠離之另一端各別連接該環形輻射部。 較佳地，該第一線段與第二線段的總長相差四分之一 波長。 ❹200926521 IX. Description of the Invention: [Technical Field] The present invention relates to a circularly polarized antenna, and more particularly to a reduced circularly polarized antenna. [Prior Art] With the increasing popularity of Radio Frequency Identification System (RFID) applications, object recognition is faster and safer. And for the convenience of users to carry or use, light and thin become the main design trend of electronic products. Therefore, when circularly polarized antennas are applied to these electronic products, the size of the antenna becomes one of the important considerations when designing the antenna. The design of general circularly polarized planar antennas can be divided into single feed and double feed. A single-input circularly polarized antenna can use a perturbation method such as a truncated angle, a slotted hole, or a narrow slot to make the original orthogonal mode excite two adjacent vertical modes of equal amplitude and 90 degrees out of phase. state. However, although such an antenna only needs a single-layer substrate, the disadvantage is that the operation bandwidth is very narrow, usually not more than one-third of the linear polarization radiation bandwidth, and the design constraints are many, and it is not easy to adjust the antenna. Circular polarization characteristics and impedance matching make design difficult. As for the dual-input circularly polarized antenna, a Wilkinson power divider or a branch-line coupler is usually used to provide excitation currents of equal amplitude and phase difference of 90 degrees, and the two feed points need to be located separately. Vertical directions to each other. Such an antenna has advantages such as a larger bandwidth of a single feed antenna and a good circular polarization characteristic of the antenna. However, since two or more substrates are required, the antenna volume becomes too large. SUMMARY OF THE INVENTION 200926521 Accordingly, it is an object of the present invention to provide a circularly polarized antenna that effectively reduces the size of an antenna without affecting the radiation efficiency of the antenna. Thus, the circularly polarized antenna of the present invention comprises a substrate, an annular radiating portion, a microstrip radiating portion and a ground plane. The substrate has an opposite first side and a second side. The annular radiating portion is disposed on the first side of the substrate. The microstrip light-emitting portion is disposed in a space surrounded by the annular radiating portion, and includes a first line segment and a second line segment, wherein one end of the two line segments are adjacent to each other for feeding signals, and the other ends are separated and respectively connected The annular radiating portion. The ground plane is disposed on the second surface of the substrate. Preferably, the circularly polarized antenna further includes a feed unit for evenly distributing the power of the feed signal, and includes a feed portion disposed in a space surrounded by the annular radiating portion and a resistor, the feed portion including a feed line segment and a transimpedance line segment extending outwardly from one end of the feed line segment, the two rotation resistance line segments respectively ending at adjacent ends of the first line segment and the second line segment and respectively connecting the first line segment And a second line segment, and the two ends of the resistor are connected to one end of the second line segment adjacent to the first line segment and the second line segment. Preferably, the other end of the feed line segment is further provided with a through hole penetrating through the first side and the second side of the substrate, for connecting an SMA connector to feed the signal, so that the center feed line of the SMA connector is The feed line segment is electrically connected, and a ground end of the SMA connector is electrically connected to a ground plane provided on the second surface of the substrate via the through hole. Alternatively, the feeding unit may be a power splitter connected to the adjacent end of the first line segment and the second line segment for distributing the feed signal power to feed the average to the first line segment and the second Line segment. 6 200926521 Angle Preferably, the annular radiating portion may be an annular structural metal wire of m-ring, square-ring, ring-shaped or elliptical ring. Preferably, the first line segment and the second line segment may be L-shaped bent or arc-shaped metal line segments, and the first line segment and the second line segment are vertically connected to each other at a distance from each other. Annular radiation. Preferably, the first line segment differs from the total length of the second line segment by a quarter wavelength. ❹
較佳地，該接地面可以是一矩形、圓形、三角形或與 該基板近似形狀的金屬平面。 較佳地，該饋入線段可以是長條形、L形或圓盤形之金 屬線段。 較佳地’該轉阻線段可以是圓弧形、矩形或L形彎折 之金屬線段。 較佳地’該基板可以是玻璃纖維基板或陶瓷基板。 較佳地，該基板可以是矩形或圓盤形。 本發明之圓極化天線具有結構簡單、尺寸短小、圓極 化轴比頻寬大、收發角度廣且增益高等優點，因此十分適 合應用於無線通訊系統之天線設計上，尤其適合輕薄短小 之電子通訊產品，具有極高的產業價值。 【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較佳實施例的詳細說明中，將可清 楚的呈現。 參見圖1及圖2，是本發明圓極化天線的一較佳實施例 7 200926521 ，本實施例之圓極化天線1應用在920 MHz之操作頻率， 其包括一基板11、一接地面12、一環形輻射部13、_微帶 輻射部14及一饋入單元15。Preferably, the ground plane may be a rectangle, a circle, a triangle or a metal plane having an approximate shape to the substrate. Preferably, the feed line segment may be an elongated, L-shaped or disc-shaped metal segment. Preferably, the transimpedance line segment may be a circular arc, rectangular or L-shaped bent metal line segment. Preferably, the substrate may be a glass fiber substrate or a ceramic substrate. Preferably, the substrate may be rectangular or disc shaped. The circularly polarized antenna of the invention has the advantages of simple structure, short size, large circular polarization axis ratio, wide transmission and reception angle and high gain, and is therefore suitable for antenna design of a wireless communication system, especially suitable for light and short electronic communication. The product has a very high industrial value. The above and other technical contents, features and effects of the present invention will be apparent from the following detailed description of the preferred embodiments. Referring to FIG. 1 and FIG. 2, a preferred embodiment of the circularly polarized antenna of the present invention is 7 200926521. The circularly polarized antenna 1 of the present embodiment is applied to an operating frequency of 920 MHz, and includes a substrate 11 and a ground plane 12 . An annular radiating portion 13, a microstrip radiating portion 14, and a feeding unit 15.
Ο 基板11具有相反的一第一面111及一第二面112，在 本實施例中’基板11是一矩形的玻璃纖維板（FR4)，其尺寸 為95 X 95 mm2 ’環形輻射部13及微帶輻射面14設於基板 11的第一面111，接地面12設於基板π的第二面U2。接 地面11在本實施例中是一設於基板u第二面112中央的矩 形金屬平面’其尺寸為64 X 64 mm2。 值得一提的是，本實施例之基板1〇並不以矩形為限， 它也可以是圓盤形或其它相似形狀，且其材質除了玻璃纖 維板(FR4)外’也可以使用陶竟基板或其它可用的介質材料 。而接地面12亦不以矩形為限’它也可以是圓形三角形 或與基板10近似形狀的金屬平面。 環形輻射部13是-封閉路徑金屬線段，在本實施則 ，該封閉路徑金屬線段為—環繞基板u第_自⑴周邊存 方環形金屬線段，其内環邊長為76随，外環邊長為⑽ :=輕㈣13並不以方環形為限，它也可以是議 - 形、橢圓形或其它相似之環形結構。 射部14設於環形輻射部13所環繞的空間中 並匕括一第一線段141及一坌_ 4 142 第—線奴M2，且兩線段141、 142的總長相差四分之一油具 141 ' 142 & ，在本實施例中，該二線名 一呈折的金屬線&，其1 、1ΦΜΙ 鄰近以饋入訊號，另-端相德M 4 143 144木 死另端相遠離且概呈 200926521 接於環形輻射部13相鄰的兩邊131、132的内環邊長中點 ，第一線段141的總長為59mm，第二線段142的總長為 104mm。且第一線段141及第二線段142除了 L形彎折結 構外，也可以是圓弧形之金屬線段。 饋入單το 15設在環形輻射部13所環繞的空間中其 包括一饋入部151及一電阻152。 饋入部151包含一饋入線段153及二轉阻線段154、 155。饋入線段153位於第一線段141及第二線段142所圈 圍的空間中，疋一長度為10.3mm，寬度為3mm的長條形金 屬線段，其一端150設有一貫穿基板η第一面in和第二 面112的貫孔156，其孔徑直徑為i 3mm，供一 SMA接頭（ 圖未示）連接以饋入訊號，使SMA接頭的中心饋入線與饋入 線段153 —端150電連接，而SMA接頭的接地端則經由貫 孔156與第二面112的接地面12電連接。 該二轉阻線段154、155由饋入線段153的另一端向外 延伸且分別終止於第一線段141及第二線段142相鄰近的 一端143、144並分别連接該端143、144，在本實施例中， 該二轉阻線段154、155是一弧長為48.07mm、寬為i.6mm 的圓弧形金屬線段。 電阻152的兩端連接在該二轉阻線段154、155之連接 第一線段141及第二線段142的一端之間，其阻抗值為ι〇〇 歐姆。 上述饋入單元15的作用在於使饋入訊號的輸入功率可 以平均分配給第一線段141及第二線段142。其中饋入線段 200926521 153除了長條形外，也可以是L形或圓盤形之金屬線段，而 轉阻線段154、155除了圓弧形外，也可以是矩形、L形彎 折或其它相似形狀之金屬線段。當然饋入單元15並不限於 使用上述微帶線結構’它也可以用其它可將饋入訊號能量 平均分配成多個輸出的習知功率分配器來實現。 參見圖3至圖8，為本實施例圓極化天線1之實作量測 結果’由圖3之反射損失結果可得到天線的阻抗頻寬，即 以Y軸10dB為準橫切過去，對應曲線所得之頻寬為 762〜1175MHz，即 1175-762=413MHz。 圖4所示為本實施例圓極化天線之史密斯圖的實驗結 果’圖5及圖6為天線在操作頻率920MHz的輻射場型量測 結果，在漣波約在〇〜3Db的情況下，圓極化天線1接收的 半功率波束角度可達90度。圖7則為操作頻帶内之圖極化 天線軸比的實驗結果，本實施例之圓極化天線1之轴比頻 寬以Y軸3dB為準橫切過去，對應曲線所得之頻寬為 866〜982MHz，即982-866=116MHz。圖8則為操作頻帶内 之圓極化天線1的增益實驗量測結果，本實施例之圓極化 天線1在操作頻帶内的增益在4.5〜6.2dBi之間。 由上述說明可知’本實施例之圓極化天線1的結構十 分簡單’其由一正方形的玻璃纖維板當作基板1〇，並於此 基板Π的第一面U1上設置一環形輻射部13、一微帶賴射 部14及一饋入單元15,且在第二面112設置一接地面12’ 並將微帶輻射部14及饋入單元15設於環形輻射單13中， 由饋入單元15將饋入訊號之輸入功率平均分配為等振幅且 10 200926521 相位相差90度的兩個輸出能量，並經由微帶輻射部μ之 總長相差四分之一波長的第一線段141及第二線段142以 概呈相互垂直方式連接至環形輻射部13，以激發出天線的 圓極化特，並作電磁波輻射與接收，而且藉由改變第一 線段141或第二線段142在環形輻射部丨3中的連接位置， 可以輕易地改變天線圓極化波的特性，亦即當第一線段ΐ4ι 連接環形輻射部13的左邊，第二線段142連接環形輻射部 13的下邊時，可得到一右旋圓極化波（rhcp)，反之若將第 一線段141連接環形輻射部13的右邊，第二線段142連接 %形輻射部13的下邊時，可得到一左旋圓極化波（LHCp)。 综上所述，本實施例之圓極化天線〖具有結構簡單、 尺寸短小、圓極化軸比頻寬大、收發角度廣且增益高等優 點，因此十分適合應用於無線通訊系統之天線設計上，尤 其適合輕薄紐小之電子通訊產品，具有極高的產業價值。 惟以上所述者’僅為本發明之較佳實施例而已，當不 能以此限定本發明實施之範圍，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。 【圖式簡單說明】 圖1為本發明圓極化天線之一較佳實施例之立體圖。 圖2為本實施例圓極化天線之平面圖； 圖3為本實施例圓極化天線的反射損失實測數據圖； 圖4為本實施例圓極化天線的實驗結果史密斯圖； 圖5為本實施例圓極化天線在χ_ζ平面的輻射場型實 11 200926521 驗結果； 圖6為本實施例圓極化天線在Y-Z平面的輻射場型實 驗結果； 圖7為本實施例圓極化天線在操作頻帶内之天線軸比 實驗結果；及 圖8為本實施例圓極化天線在操作頻帶内之天線增益 實驗結果。基板 The substrate 11 has an opposite first surface 111 and a second surface 112. In the present embodiment, the substrate 11 is a rectangular fiberglass plate (FR4) having a size of 95 X 95 mm 2 'the annular radiation portion 13 and the micro The radiation surface 14 is provided on the first surface 111 of the substrate 11, and the ground surface 12 is provided on the second surface U2 of the substrate π. In the present embodiment, the ground 11 is a rectangular metal plane disposed at the center of the second surface 112 of the substrate u having a size of 64 X 64 mm2. It should be noted that the substrate 1 本 of the embodiment is not limited to a rectangular shape, and may also be a disc shape or the like, and the material thereof may be used in addition to the fiberglass board (FR4). Other available media materials. The ground plane 12 is also not limited to a rectangular shape. It may also be a circular triangle or a metal plane having an approximate shape to the substrate 10. The annular radiating portion 13 is a closed-path metal wire segment. In the present embodiment, the closed-path metal wire segment is an annular metal wire segment surrounding the substrate u from the (1) peripheral ring, and the inner ring side length is 76, and the outer ring side length is It is (10):=light (four)13 is not limited to a square ring, it can also be a dome-shaped, elliptical or other similar ring structure. The shooting portion 14 is disposed in the space surrounded by the annular radiating portion 13 and includes a first line segment 141 and a 坌_4 142 first line slave M2, and the total length of the two line segments 141, 142 differs by a quarter. 141 ' 142 & , in this embodiment, the two-line name is a folded metal wire & 1, 1 , 1Φ 邻近 adjacent to the feed signal, and the other end - end M 4 143 144 wood dead end And generally, 200926521 is connected to the midpoint of the inner side of the two sides 131, 132 adjacent to the annular radiating portion 13, the total length of the first line segment 141 is 59 mm, and the total length of the second line segment 142 is 104 mm. The first line segment 141 and the second line segment 142 may be arc-shaped metal segments in addition to the L-shaped bent structure. The feed unit το 15 is disposed in a space surrounded by the annular radiating portion 13 and includes a feed portion 151 and a resistor 152. The feeding portion 151 includes a feeding line segment 153 and two transimpedance line segments 154, 155. The feeding line segment 153 is located in a space surrounded by the first line segment 141 and the second line segment 142, and has a length of 10.3 mm and a strip-shaped metal line segment having a width of 3 mm, and one end 150 is provided with a first surface penetrating through the substrate η. The through hole 156 of the second surface 112 and the second surface 112 have an aperture diameter of i 3 mm. An SMA connector (not shown) is connected to feed the signal, so that the center feed line of the SMA connector is electrically connected to the end portion 150 of the feed line segment 153. The ground end of the SMA connector is electrically connected to the ground plane 12 of the second surface 112 via the through hole 156. The two transposed line segments 154, 155 extend outwardly from the other end of the feed line segment 153 and terminate at adjacent ends 143, 144 of the first line segment 141 and the second line segment 142, respectively, and are connected to the ends 143, 144, respectively. In this embodiment, the two-resistance line segments 154 and 155 are arc-shaped metal wire segments having an arc length of 48.07 mm and a width of i.6 mm. The two ends of the resistor 152 are connected between the first line segment 141 and one end of the second line segment 142, and the impedance value is ι ohm. The function of the feed unit 15 is such that the input power of the feed signal can be equally distributed to the first line segment 141 and the second line segment 142. The feed line segment 200926521 153 may be an L-shaped or disc-shaped metal line segment in addition to the elongated strip shape, and the transimpedance line segments 154, 155 may be rectangular, L-shaped, or the like in addition to the circular arc shape. Shaped metal segments. Of course, the feed unit 15 is not limited to the use of the above-described microstrip line structure. It can also be implemented by other conventional power dividers that can evenly distribute the feed signal energy into a plurality of outputs. Referring to FIG. 3 to FIG. 8 , the actual measurement results of the circularly polarized antenna 1 of the present embodiment can be obtained from the reflection loss result of FIG. 3 , that is, the impedance bandwidth of the antenna is obtained, that is, the Y-axis is 10 dB, and the corresponding The resulting bandwidth is 762~1175MHz, which is 1175-762=413MHz. 4 is an experimental result of the Smith chart of the circularly polarized antenna of the present embodiment. FIG. 5 and FIG. 6 are measurement results of the radiation field type of the antenna at an operating frequency of 920 MHz, and in the case where the chopping is about 3~3 Db, The circularly polarized antenna 1 receives a half power beam angle of up to 90 degrees. 7 is an experimental result of the axial ratio of the polarized antenna in the operating frequency band. The axial specific bandwidth of the circularly polarized antenna 1 of the present embodiment is transversely cut by 3 dB on the Y-axis, and the bandwidth obtained by the corresponding curve is 866. ~982MHz, ie 982-866=116MHz. Fig. 8 is a gain experimental measurement result of the circularly polarized antenna 1 in the operating band, and the gain of the circularly polarized antenna 1 in the operating band in the operating band is between 4.5 and 6.2 dBi. It can be seen from the above description that the structure of the circularly polarized antenna 1 of the present embodiment is very simple, and that a square fiberglass board is used as the substrate 1 , and an annular radiating portion 13 is disposed on the first surface U1 of the substrate stack. a microstrip portion 14 and a feed unit 15 , and a ground plane 12 ′ is disposed on the second surface 112 and the microstrip radiation portion 14 and the feed unit 15 are disposed in the annular radiation unit 13 by the feed unit 15 equally, the input power of the feed signal is equally divided into two output energies of equal amplitude and 10 200926521 with a phase difference of 90 degrees, and the first line segment 141 and the second phase of the quarter-wavelength of the microstrip radiation portion μ are separated by a quarter wavelength. The line segment 142 is connected to the annular radiating portion 13 in a substantially perpendicular manner to excite the circular polarization of the antenna and to radiate and receive electromagnetic waves, and to change the first line segment 141 or the second line segment 142 in the annular radiating portion. The connection position in the crucible 3 can easily change the characteristic of the circularly polarized wave of the antenna, that is, when the first line segment ΐ4ι is connected to the left side of the annular radiating portion 13, and the second line segment 142 is connected to the lower side of the annular radiating portion 13, Right-handed circularly polarized wave When RHCP), and vice versa if the first line segment 141 is connected to the right of the annular portion 13 of the radiation, the second line segment connecting the lower 142% shaped radiating portion 13, a left-handed circularly polarized wave is obtained (LHCp). In summary, the circularly polarized antenna of the present embodiment has the advantages of simple structure, short size, large circular polarization axis ratio, wide transmission and reception angle, and high gain, so it is very suitable for antenna design of a wireless communication system. Especially suitable for light and thin New Zealand electronic communication products, with a high industrial value. However, the above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention, All remain within the scope of the invention patent. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of a preferred embodiment of a circularly polarized antenna of the present invention. 2 is a plan view of a circularly polarized antenna of the present embodiment; FIG. 3 is a measured data of a reflection loss of a circularly polarized antenna according to the present embodiment; FIG. 4 is a Smith chart of the experimental result of the circularly polarized antenna of the present embodiment; The radiation field pattern of the circularly polarized antenna in the χ_ζ plane is 11 200926521; FIG. 6 is the experimental result of the radiation pattern of the circularly polarized antenna in the YZ plane of the present embodiment; FIG. 7 is a circularly polarized antenna of the present embodiment. The antenna axis ratio in the operating band is compared with the experimental result; and FIG. 8 is an experimental result of the antenna gain of the circularly polarized antenna in the operating band of the present embodiment.
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【主要元件符號說明】 2 圓極化天線 12接地面 14微帶輻射部 111第一面 131 、 132 邊 142第二線段 151饋入部 153饋入線段 156貫孔 11基板 13環形輻射部 1 5饋入單元 112第二面 141第一線段 143 、 144 、 150 端 152電阻 154、155轉阻線段[Main component symbol description] 2 Circularly polarized antenna 12 ground plane 14 Microstrip radiation portion 111 First surface 131, 132 Edge 142 Second line segment 151 Feeding portion 153 Feeded into line segment 156 Through hole 11 Substrate 13 Annular radiation portion 1 5 feed Injecting unit 112 second surface 141 first line segment 143, 144, 150 end 152 resistance 154, 155 transimpedance line segment
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