Patent Grant
12191584
This application claims priority of Taiwan Patent Application No. 110120586 filed on Jun. 7, 2021, the entirety of which is incorporated by reference herein.
The disclosure generally relates to an antenna structure, and more particularly, to a multi-feed antenna structure.
With the advancements being made in mobile communication technology, mobile devices such as portable computers, mobile phones, multimedia players, and other hybrid functional portable electronic devices have become more common. To satisfy consumer demand, mobile devices can usually perform wireless communication functions. Some devices cover a large wireless communication area; these include mobile phones using 2G, 3G, and LTE (Long Term Evolution) systems and using frequency bands of 700 MHz, 850 MHz, 900 MHz, 1800 MHz, 1900 MHz, 2100 MHz, 2300 MHz, and 2500 MHz. Some devices cover a small wireless communication area; these include mobile phones using Wi-Fi and Bluetooth systems and using frequency bands of 2.4 GHz, 5.2 GHz, and 5.8 GHz.
Wireless access points are indispensable elements for mobile devices in a room to connect to the Internet at a high speed. However, since an indoor environment can experience serious signal reflection and multipath fading, wireless access points should process signals from a variety of directions of transmission and polarization simultaneously. Accordingly, it has become a critical challenge for current designers to design a wideband antenna with multiple polarization directions in the limited space of a wireless access point.
In an exemplary embodiment, the invention is directed to an antenna structure that includes a ground element, a first radiation element, a second radiation element, a dielectric substrate, a first feeding element, a second feeding element, a third feeding element, and a fourth feeding element. The dielectric substrate has a first surface and a second surface which are opposite to each other. The first radiation element is disposed on the first surface. The ground element is disposed on the second surface. The second radiation element is adjacent to the first radiation element, and is separated from the first radiation element. The first feeding element has a first feeding port, and is coupled to the first radiation element. The second feeding element has a second feeding port, and is coupled to the first radiation element. The third feeding element has a third feeding port, and is coupled to the first radiation element. The fourth feeding element has a fourth feeding port, and is coupled to the first radiation element. The antenna structure covers an operational frequency band.
The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:
In order to illustrate the purposes, features and advantages of the invention, the embodiments and figures of the invention are shown in detail as follows.
Certain terms are used throughout the description and following claims to refer to particular components. As one skilled in the art will appreciate, manufacturers may refer to a component by different names. This document does not intend to distinguish between components that differ in name but not function. In the following description and in the claims, the terms “include” and “comprise” are used in an open-ended fashion, and thus should be interpreted to mean “include, but not limited to . . . ”. The term “substantially” means the value is within an acceptable error range. One skilled in the art can solve the technical problem within a predetermined error range and achieve the proposed technical performance. Also, the term “couple” is intended to mean either an indirect or direct electrical connection. Accordingly, if one device is coupled to another device, that connection may be through a direct electrical connection, or through an indirect electrical connection via other devices and connections.
The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.
Furthermore, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.
The ground element 110 provides a ground voltage. The first radiation element 120 may substantially have a circular shape. The dielectric substrate 140 may be an FR4 (Flame Retardant 4) substrate, a PCB (Printed Circuit Board), or an FPC (Flexible Printed Circuit Board). The dielectric substrate 140 has a first surface E1 and a second surface E2 which are opposite to each other. The first radiation element 120 is disposed on the first surface E1 of the dielectric substrate 140. The ground element 110 is disposed on the second surface E2 of the dielectric substrate 140. The area of the ground element 110 may be much greater than the area of the first radiation element 120.
The second radiation element 130 may substantially have another circular shape (a larger circular shape). The area of the second radiation element 130 may be greater than the area of the first radiation element 120. The second radiation element 130 shares the same center axis CC with the first radiation element 120. The center axis CC may be substantially perpendicular to the first surface E1 of the dielectric substrate 140. That is, the center of the second radiation element 130 may overlap the center of the first radiation element 120. The center axis CC may pass through the aforementioned two centers of circles. The second radiation element 130 is disposed adjacent to the first radiation element 120, and is completely separated from the first radiation element 120. In other words, the second radiation element 130 is floating. It should be noted that the term “adjacent” or “close” over the disclosure means that the distance (spacing) between two corresponding elements is smaller than a predetermined distance (e.g., 5 mm or the shorter), but it often does not mean that the two corresponding elements touch each other directly (i.e., the aforementioned distance/spacing therebetween is reduced to 0). In some embodiments, the second radiation element 130 is substantially parallel to the first radiation element 120, and a coupling gap GC1 is formed between the second radiation element 130 and the first radiation element 120. In addition, if the second radiation element 130 has a vertical projection on the first surface E1 of the dielectric substrate 140, the whole first radiation element 120 will be inside the vertical projection of the second radiation element 130.
The first feeding element 150, the second feeding element 160, the third feeding element 170, and the fourth feeding element 180 are all disposed on the first surface E1 of the dielectric substrate 140. These feeding elements and the first radiation element 120 may be coplanar. For example, each of the first feeding element 150, the second feeding element 160, the third feeding element 170, and the fourth feeding element 180 may substantially have a polyline shape, a straight-line shape, or a meandering shape, but it is not limited thereto.
The first feeding element 150 has a first end 151 and a second end 152. A first feeding port FP1 is positioned at the first end 151 of the first feeding element 150. The second end 152 of the first feeding element 150 is coupled to a first connection point CP1 on the first radiation element 120. The second feeding element 160 has a first end 161 and a second end 162. A second feeding port FP2 is positioned at the first end 161 of the second feeding element 160. The second end 162 of the second feeding element 160 is coupled to a second connection point CP2 on the first radiation element 120. The third feeding element 170 has a first end 171 and a second end 172. A third feeding port FP3 is positioned at the first end 171 of the third feeding element 170. The second end 172 of the third feeding element 170 is coupled to a third connection point CP3 on the first radiation element 120. The fourth feeding element 180 has a first end 181 and a second end 182. A fourth feeding port FP4 is positioned at the first end 181 of the fourth feeding element 180. The second end 182 of the fourth feeding element 180 is coupled to a fourth connection point CP4 on the first radiation element 120. The first connection point CP1, the second connection point CP2, the third connection point CP3, and the fourth connection point CP4 are different from each other, and they may be all arranged on the circumference of the first radiation element 120. In some embodiments, the first feeding element 150, the second feeding element 160, the third feeding element 170 and the fourth feeding element 180 are substantially the same length, so as to provide almost the same phase delay.
In some embodiments, the first feeding element 150, the second feeding element 160, the third feeding element 170, and the fourth feeding element 180 are variable-width structures. Specifically, the first feeding element 150 includes a first narrow portion 154 and a first wide portion 155. The first feeding port FP1 is coupled through the first narrow portion 154 and the first wide portion 155 to the first connection point CP1. The second feeding element 160 includes a second narrow portion 164 and a second wide portion 165. The second feeding port FP2 is coupled through the second narrow portion 164 and the second wide portion 165 to the second connection point CP2. The third feeding element 170 includes a third narrow portion 174 and a third wide portion 175. The third feeding port FP3 is coupled through the third narrow portion 174 and the third wide portion 175 to the third connection point CP3. The fourth feeding element 180 includes a fourth narrow portion 184 and a fourth wide portion 185. The fourth feeding port FP4 is coupled through the fourth narrow portion 184 and the fourth wide portion 185 to the fourth connection point CP4. According to practical measurements, such a variable-width design can fine-tune the feeding impedance of the antenna structure 100. However, the invention is not limited thereto. In alternative embodiments, adjustments are made such that the first feeding element 150, the second feeding element 160, the third feeding element 170, and the fourth feeding element 180 are equal-width structures. In other embodiments, adjustments are made such that the first feeding element 150, the second feeding element 160, the third feeding element 170, and the fourth feeding element 180 are multi-segment structures (e.g., more than two segments, any two of which are not parallel to each other) or taper-width structures.
A first angle θ1 is formed between the second wide portion 165 of the second feeding element 160 and the first wide portion 155 of the first feeding element 150. A second angle θ2 is formed between the third wide portion 175 of the third feeding element 170 and the second wide portion 165 of the second feeding element 160. A third angle θ3 is formed between the fourth wide portion 185 of the fourth feeding element 180 and the third wide portion 175 of the third feeding element 170. For example, the extension line of each of the first wide portion 155, the second wide portion 165, the third wide portion 175, and the fourth wide portion 185 can pass through the center axis CC. In some embodiments, the first angle θ1, the second angle θ2, and the third angle θ3 are substantially equal to each other. In alternative embodiments, the first angle θ1 is defined between the second connection point CP2 and the first connection point CP1, the second angle θ2 is defined between the third connection point CP3 and the second connection point CP2, and the third angle θ3 is defined between the fourth connection point CP4 and the third connection point CP3. For example, two sides of the corresponding angle can be defined by connecting any two adjacent connection points to the center axis CC, respectively, but they are not limited thereto.
In some embodiments, the antenna structure 100 can covers an operational frequency band from 2400 MHz to 2500 MHz, and its operational principles will be described as follows. The feeding energy from a signal source (not shown) can be entered via any two of the first feeding port FP1, the second feeding port FP2, the third feeding port FP3 and the fourth feeding port FP4, so as to excite the antenna structure 100. The second radiation element 130 can be excited by the first radiation element 120 using a coupling mechanism, so as to enhance the radiation pattern of the antenna structure 100. With such a design, the antenna structure 100 can support at least the wideband operation of WLAN (Wireless Local Area Network) 2.4 GHz.
In some embodiments, the antenna structure 100 operates in either a first mode or a second mode, so as to provide different polarization directions. In the first mode, the first feeding port FP1 and the third feeding port FP3 are both enabled (or in use), and the second feeding port FP2 and the fourth feeding port FP4 are both disabled (or not in use), where a first feeding phase difference is provided between the first feeding port FP1 and the third feeding port FP3. In the second mode, the second feeding port FP2 and the fourth feeding port FP4 are both enabled, and the first feeding port FP1 and the third feeding port FP3 are both disabled, where a second feeding phase difference is provided between the second feeding port FP2 and the fourth feeding port FP4. For example, each of the first feeding phase difference and the second feeding phase difference may be equal to 0, 45, 90, 135 or 180 degrees, but it is not limited thereto. The antenna structure 100 can provide a variety of polarization directions by appropriately selecting the feeding ports and the feeding phase difference therebetween.
In some embodiments, the element sizes of the antenna structure 100 will be described as follows. The radius R1 of the first radiation element 120 may be substantially equal to 0.25 guided wavelength (i.e., λg/4, where “guided wavelength λg” is defined in the dielectric substrate 140 and is adjustable according to the dielectric constant of the dielectric substrate 140) of the operational frequency band of the antenna structure 100. The radius R2 of the second radiation element 130 may be substantially equal to 0.25 free-space wavelength (i.e., λf/4, where “free-space wavelength λf” is defined in free space) of the operational frequency band of the antenna structure 100. For example, the radius R2 of the second radiation element 130 may be substantially two times the radius R1 of the first radiation element 120. The width of the coupling gap GC1 between the second radiation element 130 and the first radiation element 120 may be substantially equal to 0.05 free-space wavelength (i.e., λf/20) of the operational frequency band of the antenna structure 100. The thickness H1 of the dielectric substrate 140 may be from 0.4 mm to 1.6 mm. The dielectric constant of the dielectric substrate 140 may be from 2 to 16. The first angle θ1 between the second wide portion 165 of the second feeding element 160 and the first wide portion 155 of the first feeding element 150 may be substantially equal to 45 degrees. The second angle θ2 between the third wide portion 175 of the third feeding element 170 and the second wide portion 165 of the second feeding element 160 may be substantially equal to 45 degrees. The third angle θ3 between the fourth wide portion 185 of the fourth feeding element 180 and the third wide portion 175 of the third feeding element 170 may be substantially equal to 45 degrees. The above ranges of element sizes are calculated and obtained according to many experiment results, and they help to optimize the tunable polarization, operational bandwidth and impedance matching of the antenna structure 100.
The invention proposes a novel antenna structure. In comparison to the conventional design, the invention has at least the advantages of multiple polarizations, small size, wide bandwidth, and low manufacturing cost. Therefore, the invention is suitable for application in a variety of communication devices.
Note that the above element sizes, element shapes, and frequency ranges are not limitations of the invention. An antenna designer can fine-tune these settings or values according to different requirements. It should be understood that the antenna structure of the invention is not limited to the configurations of
Use of ordinal terms such as “first”, “second”, “third”, etc., in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having the same name (but for use of the ordinal term) to distinguish the claim elements.
While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.
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| 110120586 | Jun 2021 | TW | national |
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