200903893 、九、發明說明： 【發明所屬之技術領域】 . 本發明涉及一種天線，尤其涉及一種平面天線。 【先前技術】 近年來，由於移動通訊産品之市場需求大增，使得無線通 訊之發展更為迅速，在眾多無線通訊標準中，最引人注目的為 美國電子電機工程師協會（Institute of Electrical and Electronics Engineers，IEEE)制定的 802.11 無線區域網路 (Wireless Local Area Network，WLAN )協定。該協定制定於 1997年，其不僅提供了無線通訊上許多前所未有之功能，而且 提供了可令各種不同品牌之無線通訊產品得以相通之解決方 案。在IEEE所制定的諸多標準中IEEE 802.llb/g為當前較常 用之標準，其工作頻段為2.4GHz。 天線為移動通訊產品中之一必備高頻組件，其主要功能係 <用來接收及發射電磁波訊號。由於無線通訊產品均朝向輕、 薄、短、小之方向發展，故要求天線所佔面積亦應相應較小。 故如何在兼顧天線之效能的前提下，同時將天線之所佔的面積 減小乃當今天線設計之一大挑戰。 【發明内容】 有鑑於此’有必要提供一種平面天線，使天線所佔據的面 積有效縮小’其可工作於中心頻率為2.4GHz。 一種平面天線’設置於一基板上’用於接收及發射電磁波 6 200903893 訊號。平面天線包括一接地部、一輻射體、一饋入部以及一匹 配部。接地部設置於基板之表面。輻射體包括一第一輻射段、 一第二輻射段、一第三輻射段、一第四輻射段以及一第五輻射 段。第一輻射段、第二輻射段、第三輻射段、第四輻射段以及 第五輻射段依次垂直連接且同向彎折。饋入部與該接地部相鄰 設置，且電性連接於輻射體，用於向輻射體饋入電磁波訊號。 匹配部電性連接於輻射體及接地部之間，且電性連接於饋入 部。 藉由以下對具體實施方式詳細的描述結合附圖，將可輕易 的瞭解上述内容及此項發明之諸多優點。 【實施方式】 請參閱圖1，所示為本發明一實施方式中平面天線10之示 意圖。 在本實施方式中，平面天線10設置於一基板20上，用於 接收及發射電磁波訊號。平面天線10包括一接地部12、一輻 射體16、一饋入部14以及一匹配部18。接地部12設置於基 板20之表面。饋入部14電性連接於輻射體16，用於向輻射體 16饋入電磁波訊號，饋入部14之電阻值約為50歐姆。匹配部 18電性連接於輻射體16及接地部12之間，且電性連接於饋入 部14。 在本實施方式中，輻射體16包括一第一輻射段161、一第 二輻射段162、一第三輻射段163、一第四輻射段164以及一 200903893 第五輪射段165。第一輻射段161與饋入部14電性連接，在實 際應用中，第—輻射段161與饋入部14可如圖1所示之處於 同直線上亦可如圖2所示之二者呈垂直連接關係。第一輻 射段161、第二輻射段162、第三輻射段163、第四輻射段 以及第五輻射段165依次垂直連接且同向彎折形成—内螺旋。 其中’第一輪射段162與第五輻射段165平行設置。 第—&射段161、第二輻射段162及第三輻射段163圍繞 於第四幸田射#又164與第五輻射段165之外侧。第五輻射段165 之見度車乂第—輪射段161、第二輻射段162、第三輻射段163 以及第四輻射段164之寬度大，用以展寬平面天線1〇之工作 頻段。 匹配部18呈彎折狀，包括一第一匹配段181以及一與第 一匹配段181垂直電性連接之第二匹配段182。第一匹配段ι81 與接地部12垂直電性連接。第二匹配段ι82與饋入部14電性 連接，且與第二輻射段162平行。在本實施方式中，匹配部18 可以消除由輕射體16與接地部丄2產生的電抗。 。月參閱圖2 ’為本發明另一實施方式中平面天線之示意圖。 請參閱圖3，為圖1中平面天線10之尺寸標注圖。在本實 施方式中’天線10之總長度a約為10毫米，總寬度b約為8 毫米。饋入部14之長度c約為2毫来，寬度d約為0.5毫来。 第七射段161之長度e約為6毫米，寬度f約為〇·5毫米。 第二輕射段162之長度g約為8.5毫米，寬度h約為1毫米。 8 200903893 第三輻射段163之長度i約為4毫米，寬度j約為1毫米。第 四輻射段164之長度k約為2毫米，寬度m約為0.5毫米。第 五輻射段165之長度η約為6.5毫米，寬度p約為3.5毫米。 第一匹配段181之長度q約為1.5毫米，寬度r約為0.5毫米。 第二匹配段182之長度s約為3.5毫米，寬度t約為0·5毫米。 請參閱圖4，所示為圖1中平面天線10之反射損耗（Return Loss)電磁模擬圖。由圖可知，平面天線10工作於2.4GHz頻 段時，其反射損耗值小於-10dB。符合IEEE 802.11b/g標準中 平面天線之應用需求。 圖5至圖7為圖1中平面天線10之幸畐射場型圖。如圖1 所示，在本實施方式中，基板20處於X-Y平面，垂直基板20 向上的方向為Z轴方向。圖4、圖5以及圖6分別為平面天線 10於X-Y平面、Y-Z平面以及X-Z平面之輻射場型圖。由該 等電磁模擬結果可知，平面天線10之輻射場型在X-Y平面、 Y-Z平面以及X-Z平面上均為近似全向性（Omni-Directional )。 熟知本領域之技術人員可知，本發明平面天線10並非只 工作於2.4GHz頻段，只要對輻射體16的總長度及寬度稍做變 更，便可使本發明平面天線10接收其他不同頻段之電磁波訊 號。 綜上所述，本發明符合發明專利要件，爰依法提出專利申 請。惟，以上所述者僅為本發明之較佳實施方式，舉凡熟悉本 案技藝之人士，在援依本案發明精神所作之等效修飾或變化， 9 200903893 皆應包含於以下之_請專利範圍内。 -【圖式簡單說明】 圖1係本發明—實施方式中平面天線之示意圖。 圖2係本發明另—實施方式中平面天線之示意圖 圖3係圖1中平面天線之尺寸標注圖。 圖4係圖1中平面天線之反射損耗電磁模擬圖。 圖5係圖工中平面天線於χ_γ平面之幸畐射場型圖 圖6係圖i中平面天線在γ_ζ平面之幸昌射場型圖 圖7係圖工中平面天線在χ_ζ平面之輕射場型圖 【主要元件符號說明】 平面天線 10 接地部 12 饋入部 14 輻射部 16 第一輻射段 161 第一輕射段 162 第三輻射段 163 第四輻射段 164 第五輕射段 165 匹配部 18 第一匹配段 181 第二匹配段 182 20 200903893 基板 11200903893, IX. Description of the invention: [Technical field to which the invention pertains] The present invention relates to an antenna, and more particularly to a planar antenna. [Prior Art] In recent years, due to the increasing market demand for mobile communication products, the development of wireless communication has become more rapid. Among the many wireless communication standards, the most striking is the Institute of Electrical and Electronics (Institute of Electrical and Electronics). Engineers, IEEE) 802.11 Wireless Local Area Network (WLAN) protocol. Established in 1997, the agreement not only provides many of the unprecedented features of wireless communications, but also provides solutions that enable wireless communication products from a variety of brands to communicate. Among the many standards established by the IEEE, IEEE 802.11b/g is the currently more commonly used standard, and its operating frequency band is 2.4 GHz. The antenna is one of the necessary high-frequency components in mobile communication products, and its main function is to receive and transmit electromagnetic wave signals. Since wireless communication products are moving toward light, thin, short, and small, the area occupied by the antenna should be correspondingly small. Therefore, how to reduce the area occupied by the antenna while taking into account the performance of the antenna is one of the major challenges in today's antenna design. SUMMARY OF THE INVENTION In view of the need to provide a planar antenna, the area occupied by the antenna is effectively reduced, which can operate at a center frequency of 2.4 GHz. A planar antenna 'disposed on a substrate' is used to receive and emit electromagnetic waves 6 200903893 signals. The planar antenna includes a ground portion, a radiator, a feed portion, and a matching portion. The grounding portion is disposed on a surface of the substrate. The radiator includes a first radiating section, a second radiating section, a third radiating section, a fourth radiating section and a fifth radiating section. The first radiating section, the second radiating section, the third radiating section, the fourth radiating section and the fifth radiating section are vertically connected and bent in the same direction. The feeding portion is disposed adjacent to the grounding portion and electrically connected to the radiator for feeding the electromagnetic wave signal to the radiator. The matching portion is electrically connected between the radiator and the ground portion, and is electrically connected to the feeding portion. The above and many of the advantages of the invention will be readily apparent from the Detailed Description of the Detailed Description. [Embodiment] Referring to Fig. 1, there is shown a schematic view of a planar antenna 10 according to an embodiment of the present invention. In this embodiment, the planar antenna 10 is disposed on a substrate 20 for receiving and transmitting electromagnetic wave signals. The planar antenna 10 includes a ground portion 12, a radiator 16, a feed portion 14, and a matching portion 18. The ground portion 12 is provided on the surface of the substrate 20. The feeding portion 14 is electrically connected to the radiator 16 for feeding electromagnetic waves to the radiator 16, and the resistance of the feeding portion 14 is about 50 ohms. The matching portion 18 is electrically connected between the radiator 16 and the ground portion 12, and is electrically connected to the feeding portion 14. In the present embodiment, the radiator 16 includes a first radiating section 161, a second radiating section 162, a third radiating section 163, a fourth radiating section 164, and a 200903893 fifth round section 165. The first radiating section 161 is electrically connected to the feeding portion 14. In practical applications, the first radiating section 161 and the feeding portion 14 may be in the same line as shown in FIG. Connection relationship. The first radiating section 161, the second radiating section 162, the third radiating section 163, the fourth radiating section, and the fifth radiating section 165 are sequentially connected vertically and bent in the same direction to form an inner spiral. Wherein the first round shot 162 is disposed in parallel with the fifth radiant section 165. The first & amp 161, the second radiant section 162, and the third radiant section 163 surround the fourth side of the fourth Koda field # 164 and the fifth radiant section 165. The fifth radiant section 165 has a wide width of the rutted first-rotation section 161, the second radiant section 162, the third radiant section 163, and the fourth radiant section 164 for widening the working frequency band of the planar antenna. The matching portion 18 has a bent shape and includes a first matching segment 181 and a second matching segment 182 electrically connected to the first matching segment 181. The first matching segment ι81 is electrically connected perpendicularly to the ground portion 12. The second matching segment ι82 is electrically connected to the feed portion 14 and is parallel to the second radiant segment 162. In the present embodiment, the matching portion 18 can eliminate the reactance generated by the light projecting body 16 and the ground portion 丄2. . Referring to FIG. 2', a schematic diagram of a planar antenna according to another embodiment of the present invention is shown. Please refer to FIG. 3 , which is a dimension drawing of the planar antenna 10 of FIG. 1 . In the present embodiment, the total length a of the antenna 10 is about 10 mm, and the total width b is about 8 mm. The feed portion 14 has a length c of about 2 millimeters and a width d of about 0.5 millimeters. The seventh segment 161 has a length e of about 6 mm and a width f of about 〇·5 mm. The second light shot 162 has a length g of about 8.5 mm and a width h of about 1 mm. 8 200903893 The third radiating section 163 has a length i of about 4 mm and a width j of about 1 mm. The fourth radiating section 164 has a length k of about 2 mm and a width m of about 0.5 mm. The fifth radiating section 165 has a length η of about 6.5 mm and a width p of about 3.5 mm. The first matching segment 181 has a length q of about 1.5 mm and a width r of about 0.5 mm. The second matching segment 182 has a length s of about 3.5 mm and a width t of about 0.5 mm. Referring to FIG. 4, an electromagnetic simulation diagram of the return loss of the planar antenna 10 of FIG. 1 is shown. As can be seen from the figure, when the planar antenna 10 operates in the 2.4 GHz band, the reflection loss value is less than -10 dB. Meets the application requirements of planar antennas in the IEEE 802.11b/g standard. 5 to 7 are diagrams of the lucky field pattern of the planar antenna 10 of Fig. 1. As shown in FIG. 1, in the present embodiment, the substrate 20 is in the X-Y plane, and the upward direction of the vertical substrate 20 is in the Z-axis direction. 4, 5, and 6 are radiation pattern diagrams of the planar antenna 10 in the X-Y plane, the Y-Z plane, and the X-Z plane, respectively. From the results of these electromagnetic simulations, the radiation field pattern of the planar antenna 10 is approximately Omni-Directional in the X-Y plane, the Y-Z plane, and the X-Z plane. It will be understood by those skilled in the art that the planar antenna 10 of the present invention does not only operate in the 2.4 GHz frequency band. As long as the total length and width of the radiator 16 are slightly changed, the planar antenna 10 of the present invention can receive electromagnetic wave signals of other different frequency bands. . In summary, the present invention complies with the requirements of the invention patent, and proposes a patent application according to law. However, the above is only a preferred embodiment of the present invention, and those skilled in the art will be equivalently modified or changed in accordance with the spirit of the invention, and 9 200903893 should be included in the following patent scope. . - BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view of a planar antenna in the present invention. 2 is a schematic view of a planar antenna in another embodiment of the present invention. FIG. 3 is a dimensional drawing of the planar antenna in FIG. 4 is an electromagnetic simulation diagram of the reflection loss of the planar antenna of FIG. 1. Fig. 5 is a diagram of the lucky field pattern of the planar antenna in the χ γ plane. Fig. 6 is the light field pattern of the planar antenna in the γ_ζ plane. Main component symbol description] Planar antenna 10 Grounding portion 12 Feeding portion 14 Radiation portion 16 First radiating portion 161 First light-emitting portion 162 Third radiating portion 163 Fourth radiating portion 164 Fifth light-emitting portion 165 Matching portion 18 First matching Segment 181 second matching segment 182 20 200903893 substrate 11