201115832 六、發明說明： 【發明所屬之技術領域】 本發明係指一種雙頻印刷式八木天線，尤指一種具高指向性輻射 場型之雙頻印刷式八木天線。 【先前技術】 在現代化資訊社會中，各種無線通訊網路已經成為社會大眾交換 語音或文字訊息、數據'資料、影音檔案的最重要途徑之一。存取 ^4些以無線電磁波攜載資訊的無線通訊網路需要利用天線，因此， 天線的研發成為現代資訊廠商的重點之一。為了實現更小體積、方 便使用者隨身攜帶的無線通訊裝置，例如手機、個人數位助理器 (PDA)、無線USB傳輸器（Wireless USB D〇ngle)，天線的體積也 應該要能盡量縮減，以將天線整合入可攜式的通訊裝置中。 由於印刷式天線具有重f輕、體積小，且可與各種電路高度相容 專優勢目此’近年來已被廣泛地應用在各種無線通訊產品上。一 般來說’為了減少接收或發射訊號的死角，無線通訊產品中的印刷 式天線大多以「全向性」天線實現，例如印刷式偶極天線(Dipole antenna)。在水平面上，全向性天線的訊號是以三百六十度輕射短 距離内訊號的變化小，因此適合實際的應用。然而，隨著天線陣列 或智慧型天線技術的導人，單_天線往往需要具有高增益及高指向 性的天線舖場型。在此，f知技術提出—鱗刷式八木天 201115832 線（printedYagiAnte聰），其利用人木天線高指向性的特性，提高 在使用頻段上的天線增益，使通訊品質進一步達到改善的效果。巧 請參考第1圖，第1圖係一習知八木天線1〇之示意圖。八木天 線ίο具有八木天線之-最基本架構，其由一驅動器(Driver)u、一 反射器（Reflect) 12及-引向器（Direetor) 13等三個元件組成。 驅動器11通常以-偶極天線實現，用來根據饋入的時變電流產生共 振’以產生輻射電場。反射器12與引向器13則是由金屬片或金屬、 板形成’其可透過電_合分別激發出與驅動器u反相及同相的輕 射電場。如此-來，反射器12及引向器13可將偶極天線產生之輕 射場型往特定方向反射或牽引，而提高天線的增益。當然，反射器 及引向器等寄生元件數量可根據實際天線增益的需求進行調整，其 係本領域具通常知識者所知，於此不多加贅述。 一 前無線 、然而，習知印刷式八木天線為一單頻天線，其無法滿足目 #通訊產品多頻帶的需求，因此有改進的必要。 【發明内容】 因此，本發狀轉目的即在於提供_種賴_式八木天線。 本發明揭露-種雙頻印刷式八木天線，其包含有一基板、 該 第—引向器、一第二驅動器、—反射器及-傳輸線。 第一驅動ϋ形雜該基板上，用來產生—第一頻帶之細場型。 201115832 第一引向器形成於該基板上該第—驅動器沿—第一方向之一侧，用 來將該第-頻帶之ϋ射場型往該第—方向牽引。該第二驅動器形成 於該基板上該第-驅動器及該第—引向器之間，用來產生—第二頻 帶之輻射場型。其中，該第二驅動ϋ與該第-引向ϋ之-間距使該 第-引向㈣成該第二頻帶之—開路元件。該反射器形成於該基板 上該第-驅動n與該第—方向反向之H用來將該第一頻帶之 輻射場型及該第二鮮之輻射場雜該第-方向反射。該傳輸線沿 6亥第-方向械於該基板上，依序輪於該反射器 、該第一驅動器 及該第二驅動器。 【實施方式】 明參考第2圖，第2圖為本發明一雙頻印刷式八木天線20之實 施例示意圖。雙頻印刷式八木天線2〇包含有一基板21、一低頻驅 動器22、一低頻引向器23、一高頻驅動器24、一反射器25及一傳 輸線26。低頻驅動器22形成於基板21上，用來產生一低頻帶之輻 射％型。低頻引向器23形成於基板21上低頻驅動器22之一側，用 來牽引低頻帶之輻射場型往+ γ軸方向輻射。高頻驅動器24形成於 基板21上低頻驅動器22及低頻引向器23之間，用來產生一高頻帶 之輻射場型。對於高頻驅動器24所產生之高頻訊號來說，高頻驅動 器24與低頻引向器23之一間距將使低頻引向器23形同一開路元 件。反射器25形成於基板21上低頻驅動器22之另一側，用來將低 頻帶之輕射場型及高頻帶之輻射場型往+ Υ軸方向反射。傳輸線26 沿Υ軸方向形成於基板21上，依序耦接於反射器25、低頻驅動器 201115832 22及高頻驅動器24，用來將饋入訊號傳輸至低頻驅動器22及高頻 驅動器24。另外’雙頻印刷式八木天線20更包含有一高頻匹配器 27，形成於基板21上高頻驅動器24之附近，用來作為高頻驅動器 之一電抗性負載，以增加高頻帶訊號之頻寬。 在本發明實施例中，基板21可利用一 FR4雙層玻璃纖維板實 現，其具有上下兩層金屬層。低頻驅動器22及高頻驅動器24分別 由平行X軸方向之一偶極天線實現。每一偶極天線包含有兩枝輻射 •臂，分別形成於基板21之上層與下層。反射器25係以一金屬片實 現，形成於基板21之下層，並麵接於一系統地端，而低頻引向器 23及高頻匹配器27則形成於基板21之上層。傳輸線係以一微帶線 實現，其與反射器25耦接之一端形成天線之一訊號饋入端FEED。 關於又頻印刷式八木天線20的詳細結構，請參考第3圖至第5圖。 第3圖為雙頻印刷式八木天線2〇之立體圖，第4圖為雙頻印刷式八 木天線20之上層金屬佈局圖，而第5圖則為雙頻印刷式八木天線 • 20之下層金屬佈局圖。 關於印刷式八木天線之各部分詳細功能，請繼續參相下說明。 在本發明實施例中，低頻驅動器22及高頻驅動器24分別由平行於 X軸方向之偶極天線實現，用來產生高頻帶與_帶的 場 型。在不考慮反射㈣與低則向器23時，偶極天線所產生之: 2輪射場型為全向性。-絲說，偶極天線之細臂長度約為 轄射頻率姆舰長之四分之-，魏馳_2纽射器25之 201115832 距離大約為0.1〜0.25倍的低頻帶波長。 低頻引向器23主要是將低頻驅動器22所產生之輻射場型往+γ 軸方向牽引，以使低頻帶之輻射場型產生更強的指向性。一般來說， 低頻引向器23與低頻驅動器22之間的距離在設計上約為〇1〜〇 25 倍的低頻帶縣。請參考第6圖，第6 _低頻引向n 23被低頻驅 動器22之時變電流所激發之電流分布示意圖。如第6圖所示，低頻 驅動器22之時變電流與低頻引向器23上之電流為同方向，因此， 低頻引向器23對低頻驅動器22來說是一個良好的引向器，而可使 低頻帶之㈣場場型往+ Υ軸方向去輻射，此之外，本發明實施 例另適當調整低頻引向器23與高頻驅動器間之距離，使低頻引向器 23對於高頻驅動器24所產生之高頻訊號來說形同一開路元件。如 此來’低頻引向器23將不會影響到高頻驅動器％所產生之輕射 場型。 清注意’在本發明實施例中，高頻驅動器24對低頻驅動器22 來說不產生引向器之功用’主要是因為高頻驅動器24與低頻驅動器 22之距離太近’而引向器一般要距離驅動器倍的波長才會 有比較顯著的功能。 反射器25主要具有下列兩項功能：⑴作為整個天線的地端及 ⑵反射低頻驅動器22與高頻驅動器％所產生之輻射場型，使天 線的輻射場型可以擁有指向性的效果。請參考第7圖及第8圖，第 201115832 7圖及第8圖献㈣25分別被低獅動^ 22及高娜動器24之 時變電流所激發之電流分布示意圖。如第7圖所示，對於低頻帶來 說’天線的地電流方向完全與低頻驅動器22上之時變電流反向。而 如第8圖所不，對於高頻帶來說，天線的地電流方向與高頻驅動器 24上的時變電流也是反方向。也就是說，在本發明實施例中，反射 器25可以同時作為高頻驅動器與低頻驅動器之一反射板，而使高頻 帶與低頻帶的天線輻射場場型可以往+γ軸方向去輻射。 最後’高頻匹配器27用來提供一電容性阻抗，以匹配傳輸線26 產生之電感性負載，而增加高頻的反射係數頻寬且對低頻的頻寬影 響不大。對於南頻驅動器24產生之南頻訊號來說，高頻匹配器27 亦不具有引向器的效果，主要是因為其與高頻驅動器距離太近的關 係。引向器一般要距離驅動器0.1〜0.25倍的波長才會有比較顯著的 功能。因此，在本發明實施例中，高頻匹配器27為一個提升高頻帶 頻寬的阻抗匹配器。 簡s之，本發明實施例利用天線的地端同時作為低頻驅動器μ 及高頻驅動器24的反射板，並設計低頻引向器23及高頻驅動器24 的擺放位置，使低頻引向器23對低頻輻射場型有向前推拉的作用但 對向頻輻射場型卻不造成影響。如此一來，本發明實施例不需要額 外的機構或裝置來改變天線的輻射場型’即可在同一平面實現高指 向性的雙頻八木天線。 201115832 當然’上述雙頻印刷式八木天線架構可應用於任意的雙頻系統之 下，例如應用於一 IEEE 802.11之雙頻無線區域網路系統。在本發 明實施例中，雙頻印刷式八木天線20係以單端饋入（Singlefeed) 方式將訊5虎饋入至訊號饋入端feed，而在其他實施例中，亦可採 用類似傳統八木天線之差動饋入（differential fee(j)方式，但需要在 結構上增加一平衡-非平衡轉換器（Balun)。上述相關變化係本領域 具通b知識者所熟知’於此不多加贊述。 在本發明實施例中，雙頻印刷式八木天線2〇之整體尺寸大小約 為50mmx50mmxl.6mm ’而低頻驅動器及高頻驅動器則分別用來產 生對應於IEEE 802.11b/g及正EE 802.11a之操作頻率。在此情形下， 雙頻印刷式八木天線20之模擬結果分別如第9圖至第u圖所示。 第9圖為雙頻印刷式八木天線20之反射係數圖，第10A圖到第1〇c 圖為雙頻印刷式八木天線2〇之低鮮天線增益圖，而f UA圖到 第nc圖則為雙頻印刷式八木天線2〇之高頻帶天線增益圖。如第9 圖所示，若以-10dB為基準，雙頻印刷式八木天線2〇之低頻頻寬約 洛在2.39GHZ〜2.51GHz之間，而高頻頻寬則落在4 79(Μζ〜 6.46GHZ之間。由此可知，高頻匹配器27可有效增加雙頻印刷式八 木天線20之高頻帶頻寬。 比如第10圖及第11圖所示’不論是高頻還是低頻，天線輻射場型 ^具f優異的指向性。然而，由於雙頻印刷式八木天線2〇在低頻部 分比高頻部分多了-個服器，因此低頻部份的天線增益比高頻部 201115832 分的天線增益具有更好的表現。此外，雖然低頻引向器23比高頻驅 動器24來的長，只要選對適當的位置，低頻引向器23對高頻驅動 器24所產生之高頻訊號來說形同開路。 综上所述，本發明提供一種雙頻印刷式八木天線，其不需要額外 的機構或裝置來改變天線的輻射場型，而可在高頻與低頻皆擁有高 指向性的天線輻射場場型。 以上所述僅為本發明之較佳實施例，凡依本發明申請專利範圍所 做之均等變化與修飾，皆應屬本發明之涵蓋範圍。 【圖式簡單說明】 第1圖係一習知八木天線之示意圖。 第2圖為本發明一雙頻印刷式八木天線之實施例示意圖。 第3圖為第2圖中之雙頻印刷式八木天線之立體圖。 • 帛4圖為第2圖中之雙頻印刷式八木天線之上層金屬佈局圖。 第5圖為第2圖中之雙頻印刷式八木天線之下層金屬佈局圖。 第6圖為第2圖中之低頻引向器被低頻驅動器之時變電流所激發 之電流分布示意圖。 第7圖為第2圖中之反射器被低頻驅動器之時變電流所激發之電 流分布示意圖。 第8圖為第2圖中之反射器被高頻驅動器之時變電流所激發之電 流分布示意圖。 201115832 第9圖為第2圖中之勢斗5^ 第10A圖到第i〇c圖為户刷式入木天線之反射係數圖。 帶天線增益圖。^ 2圖中之雙頻印刷仏木天線之低頻 第11A圖到第lie圖為 帶天線增益圖。 之雙頻印刷式八木天線之高頻 【主要元件符號說明】 10 八木天線 11 驅動器 12 反射器 13 引向器 20 雙頻印刷式八木天線 21 基板 22 低頻驅動器 23 低頻引向器 24 高頻驅動器 25 反射器 26 傳輸線。 27 高頻匹配器 FEED 訊號饋入端201115832 VI. Description of the Invention: [Technical Field] The present invention relates to a dual-frequency printed Yagi antenna, and more particularly to a dual-frequency printed Yagi antenna with a high directivity radiation field type. [Prior Art] In the modern information society, various wireless communication networks have become one of the most important ways for the public to exchange voice or text messages, data 'data, audio and video files. Access to some wireless communication networks that carry information via wireless electromagnetic waves requires the use of antennas. Therefore, the development of antennas has become one of the focuses of modern information vendors. In order to achieve a smaller size and convenient wireless communication device for users to carry, such as a mobile phone, a personal digital assistant (PDA), and a wireless USB transmitter (Wireless USB D〇ngle), the size of the antenna should also be reduced as much as possible. The antenna is integrated into a portable communication device. Since the printed antenna has a light weight, a small size, and is highly compatible with various circuits, it has been widely used in various wireless communication products in recent years. In general, in order to reduce the dead angle of receiving or transmitting signals, printed antennas in wireless communication products are mostly implemented as "omnidirectional" antennas, such as printed dipole antennas. In the horizontal plane, the signal of the omnidirectional antenna is small in the short-range signal of 360 degrees, so it is suitable for practical applications. However, with the introduction of antenna arrays or smart antenna technologies, single-antennas often require antenna-spreading types with high gain and high directivity. Here, the F-Technology proposes the scaly brush-type Yagi-day 201115832 line (printedYagiAnte Cong), which utilizes the high directivity of the human-wood antenna to improve the antenna gain in the used frequency band and further improve the communication quality. Please refer to Figure 1, which is a schematic diagram of a conventional Yagi antenna. The Yagi Skyline ίο has the most basic structure of Yagi Antenna, which consists of three components: a driver u, a reflector 12 and a diree. The driver 11 is typically implemented as a dipole antenna for generating a resonance according to the time-varying current fed to generate a radiated electric field. The reflector 12 and the director 13 are formed of a metal piece or a metal or plate, which oscillates a light-emitting electric field which is opposite to and in phase with the driver u. As such, the reflector 12 and the director 13 can reflect or pull the light field pattern generated by the dipole antenna in a specific direction to increase the gain of the antenna. Of course, the number of parasitic elements such as reflectors and directors can be adjusted according to the actual antenna gain requirements, which are known to those skilled in the art and will not be described here. A former wireless, however, the conventional printed Yagi antenna is a single-frequency antenna, which cannot meet the needs of the multi-band of the communication product, so there is a need for improvement. SUMMARY OF THE INVENTION Therefore, the purpose of the present invention is to provide a _ _ _ Yagi antenna. The invention discloses a dual-frequency printed Yagi antenna comprising a substrate, the first director, a second driver, a reflector and a transmission line. The first driving surface is shaped on the substrate to generate a fine field type of the first frequency band. 201115832 The first director is formed on the substrate, and the first driver is along one side of the first direction, and is used to pull the field pattern of the first frequency band to the first direction. The second driver is formed on the substrate between the first driver and the first director to generate a radiation pattern of the second frequency band. The spacing between the second driving ϋ and the first guiding 使 causes the first-directed (four) to be an open circuit component of the second frequency band. The reflector is formed on the substrate, and the first drive n is opposite to the first direction by H for reflecting the radiation pattern of the first frequency band and the second fresh radiation field in the first direction. The transmission line is mechanically mounted on the substrate along the 6th direction, and sequentially rotates the reflector, the first driver and the second driver. [Embodiment] Referring to Fig. 2, Fig. 2 is a schematic view showing an embodiment of a dual-frequency printed Yagi antenna 20 of the present invention. The dual-frequency printed Yagi antenna 2A includes a substrate 21, a low frequency driver 22, a low frequency director 23, a high frequency driver 24, a reflector 25 and a transmission line 26. A low frequency driver 22 is formed on the substrate 21 for generating a low frequency band radiation % type. The low frequency director 23 is formed on one side of the low frequency driver 22 on the substrate 21 for pulling the radiation pattern of the low frequency band to radiate in the + γ axis direction. The high frequency driver 24 is formed on the substrate 21 between the low frequency driver 22 and the low frequency director 23 for generating a high frequency band radiation pattern. For the high frequency signal generated by the high frequency driver 24, a distance between the high frequency driver 24 and the low frequency director 23 will cause the low frequency director 23 to be the same open circuit element. The reflector 25 is formed on the other side of the low frequency driver 22 on the substrate 21 for reflecting the radiation field type of the low frequency band and the radiation field of the high frequency band in the + Υ axis direction. The transmission line 26 is formed on the substrate 21 along the x-axis direction, and is coupled to the reflector 25, the low frequency driver 201115832 22 and the high frequency driver 24 for transmitting the feed signal to the low frequency driver 22 and the high frequency driver 24. In addition, the 'dual-frequency printed Yagi antenna 20 further includes a high frequency matching unit 27 formed on the substrate 21 near the high frequency driver 24 for use as a reactive load of the high frequency driver to increase the bandwidth of the high frequency band signal. . In the embodiment of the present invention, the substrate 21 can be realized by an FR4 double-layer fiberglass board having two upper and lower metal layers. The low frequency driver 22 and the high frequency driver 24 are respectively realized by a dipole antenna which is one of the parallel X-axis directions. Each dipole antenna includes two radiation arms, which are respectively formed on the upper layer and the lower layer of the substrate 21. The reflector 25 is realized by a metal piece, formed on the lower layer of the substrate 21, and is connected to a system ground end, and the low frequency director 23 and the high frequency matching unit 27 are formed on the upper layer of the substrate 21. The transmission line is implemented by a microstrip line, and one end coupled to the reflector 25 forms a signal feed end FEED of the antenna. For details on the structure of the re-printed Yagi antenna 20, please refer to Figures 3 to 5. Figure 3 is a perspective view of a two-band printed Yagi antenna 2〇, Figure 4 is a top-layer metal layout of the dual-band printed Yagi antenna 20, and Figure 5 is a dual-frequency printed Yagi antenna • 20 lower metal layout Figure. For detailed functions of each part of the printed Yagi antenna, please continue to explain. In the embodiment of the present invention, the low frequency driver 22 and the high frequency driver 24 are respectively implemented by dipole antennas parallel to the X-axis direction for generating a high frequency band and a band pattern. When the reflection (4) and the low directional device 23 are not considered, the dipole antenna produces: The 2-round field type is omnidirectional. - Silk said that the length of the arm of the dipole antenna is about four quarters of the length of the damaging frequency, and the distance of the 201115832 of the Weichi _2 splicer 25 is about 0.1 to 0.25 times the low-band wavelength. The low frequency director 23 mainly pulls the radiation field generated by the low frequency driver 22 toward the + gamma axis to make the radiation pattern of the low frequency band produce stronger directivity. In general, the distance between the low frequency director 23 and the low frequency driver 22 is designed to be about 〇1 to 〇25 times lower in the low frequency band county. Referring to Fig. 6, the sixth current_low frequency leads to a current distribution diagram of n 23 excited by the time-varying current of the low frequency driver 22. As shown in FIG. 6, the time varying current of the low frequency driver 22 is in the same direction as the current on the low frequency director 23, and therefore, the low frequency director 23 is a good director for the low frequency driver 22, but In the embodiment of the present invention, the distance between the low frequency director 23 and the high frequency driver is appropriately adjusted, so that the low frequency director 23 is applied to the high frequency driver. The high frequency signals generated by 24 form the same open circuit component. Thus, the 'low frequency director 23 will not affect the light field type generated by the high frequency driver %. It should be noted that in the embodiment of the present invention, the high frequency driver 24 does not generate the effect of the director for the low frequency driver 22 'mainly because the distance between the high frequency driver 24 and the low frequency driver 22 is too close' and the director generally needs to The wavelength of the drive is only a significant function. The reflector 25 mainly has the following two functions: (1) as the ground end of the entire antenna and (2) the radiation field pattern generated by the low frequency driver 22 and the high frequency driver, so that the radiation pattern of the antenna can have a directivity effect. Please refer to Fig. 7 and Fig. 8, the current distribution diagram of the time-varying current excited by the low lion motion 22 and the high nano actuator 24, respectively, in Fig. 201115832 7 and Fig. 8 (4). As shown in Fig. 7, for the low frequency, the ground current direction of the antenna is completely opposite to the time varying current on the low frequency driver 22. As shown in Fig. 8, for the high frequency band, the ground current direction of the antenna and the time varying current on the high frequency driver 24 are also opposite directions. That is, in the embodiment of the present invention, the reflector 25 can simultaneously serve as a reflector for the high frequency driver and the low frequency driver, and the antenna field pattern of the high frequency band and the low frequency band can be de-radiated in the + γ axis direction. Finally, the high frequency matcher 27 is used to provide a capacitive impedance to match the inductive load generated by the transmission line 26, while increasing the bandwidth of the high frequency reflection coefficient and having little effect on the low frequency bandwidth. For the south frequency signal generated by the south frequency driver 24, the high frequency matcher 27 also does not have the effect of the director, mainly because of its close relationship with the high frequency driver. The director generally has a relatively significant function from 0.1 to 0.25 times the wavelength of the driver. Therefore, in the embodiment of the present invention, the high frequency matcher 27 is an impedance matcher that boosts the bandwidth of the high frequency band. In short, the embodiment of the present invention utilizes the ground end of the antenna as the reflector of the low frequency driver μ and the high frequency driver 24, and designs the placement positions of the low frequency director 23 and the high frequency driver 24 to make the low frequency director 23 There is a forward push-pull effect on the low-frequency radiation field but no effect on the opposite-frequency radiation pattern. In this way, the embodiment of the present invention does not require an additional mechanism or device to change the radiation pattern of the antenna, so that a high-frequency dual-frequency Yagi antenna can be realized in the same plane. 201115832 Of course, the above dual-band printed Yagi antenna architecture can be applied to any dual-band system, for example, to an IEEE 802.11 dual-band wireless local area network system. In the embodiment of the present invention, the dual-frequency printed Yagi antenna 20 feeds the signal to the signal feed end feed in a single-feed mode, and in other embodiments, similar to the traditional Yagi. The differential feed (j) method of the antenna, but it is necessary to add a balanced-unbalanced converter (Balun) to the structure. The above related changes are well known to those skilled in the art. In the embodiment of the present invention, the overall size of the dual-frequency printed Yagi antenna 2〇 is about 50mm×50mmxl.6mm′ while the low frequency driver and the high frequency driver are respectively used to generate the corresponding 802.11b/g and EE 802.11. The operating frequency of a. In this case, the simulation results of the dual-frequency printed Yagi antenna 20 are shown in Fig. 9 to Fig. u. Fig. 9 is a reflection coefficient diagram of the dual-frequency printed Yagi antenna 20, 10A Figure 1 to Figure 1c shows the low-energy antenna gain map of the dual-frequency printed Yagi antenna 2〇, and the f UA diagram to the nc diagram is the high-band antenna gain diagram of the dual-frequency printed Yagi antenna 2〇. 9 Figure, if based on -10dB, double The low frequency bandwidth of the printed Yagi antenna 2〇 is between 2.39GHZ and 2.51GHz, and the high frequency bandwidth is between 4 79 (Μζ~ 6.46GHZ). It can be seen that the high frequency matcher 27 can effectively increase The high-bandwidth of the dual-band printed Yagi antenna 20. For example, in the 10th and 11th pictures, the antenna radiation field type has excellent directivity regardless of high frequency or low frequency. However, due to the dual-frequency printing type The Yagi antenna 2〇 has more than a high-frequency part in the low-frequency part, so the antenna gain in the low-frequency part is better than the antenna gain of the high-frequency part 201115832. In addition, although the low-frequency director 23 is higher than The frequency driver 24 is long, and the low frequency director 23 is open to the high frequency signal generated by the high frequency driver 24 as long as the appropriate position is selected. In summary, the present invention provides a dual frequency printed type Yagi. An antenna that does not require an additional mechanism or device to change the radiation pattern of the antenna, but has a high directivity antenna field pattern at both high and low frequencies. The above is only a preferred embodiment of the present invention. Patent application patent according to the invention The equal changes and modifications made should be within the scope of the present invention. [Simplified Description of the Drawings] Figure 1 is a schematic diagram of a conventional Yagi antenna. Figure 2 is an implementation of a dual-frequency printed Yagi antenna of the present invention. Figure 3 is a perspective view of the dual-frequency printed Yagi antenna in Figure 2. • Figure 4 is the metal layout of the upper layer of the dual-frequency printed Yagi antenna in Figure 2. Figure 5 is the second diagram. The metal layout of the underlying dual-frequency printed Yagi antenna. Figure 6 is a schematic diagram of the current distribution excited by the low-frequency driver's time-varying current in the low-frequency driver in Figure 2. Figure 7 is the second diagram. Schematic diagram of the current distribution that the reflector is excited by the time-varying current of the low frequency driver. Figure 8 is a schematic diagram showing the current distribution of the reflector in Fig. 2 excited by the time-varying current of the high frequency driver. 201115832 Figure 9 is the flow diagram of Figure 2 in Figure 2. Figure 10A to Figure i〇c shows the reflection coefficient of the household brush-type antenna. With antenna gain map. ^ 2 The low frequency of the dual-frequency printed eucalyptus antenna in Fig. 11A to lie is the antenna gain map. High-frequency printed Yagi antenna high frequency [main component symbol description] 10 Yagi antenna 11 driver 12 reflector 13 director 20 dual-frequency printed Yagi antenna 21 substrate 22 low frequency driver 23 low frequency director 24 high frequency driver 25 Reflector 26 transmission line. 27 high frequency matcher FEED signal feed end
1212