Mobile device

A mobile device includes a ground element, a metal frame, a feeding connection element, a first radiation element, a second radiation element, a capacitive element, a first shorting element, a second shorting element, and a third shorting element. The first radiation element is coupled to the feeding connection element. The second radiation element includes a first portion and a second portion. The feeding connection element is coupled through the second radiation element to the metal frame. The capacitive element is coupled between the first portion and the second portion. The first shorting element, the second shorting element, and the third shorting element are coupled between the metal frame and the ground element. An antenna structure is formed by the ground element, the metal frame, the feeding connection element, the first radiation element, the second radiation element, the capacitive element, the first shorting element, and the second shorting element.

CROSS REFERENCE TO RELATED APPLICATIONS

This Application claims priority of Taiwan Patent Application No. 106145510 filed on Dec. 25, 2017, the entirety of which is incorporated by reference herein.

BACKGROUND OF THE INVENTION

Field of the Invention

The disclosure generally relates to a mobile device, and specifically, to a mobile device and an antenna structure therein.

Description of the Related Art

With the progress being made in mobile communication technology, mobile devices such as portable computers, mobile phones, tablet computers, multimedia players, and other hybrid functional mobile devices have become common. To satisfy the demands of users, mobile devices can usually perform wireless communication functions. Some functions cover a large wireless communication area; for example, 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 functions cover a small wireless communication area; for example, mobile phones using Wi-Fi and Bluetooth systems and using frequency bands of 2.4 GHz, 5.2 GHz, and 5.8 GHz.

In order to improve the device's appearance, current designers often incorporate metal elements into mobile devices. However, these added metal elements tend to negatively affect the antennas used for wireless communication in mobile devices, thereby degrading the overall communication quality of mobile devices. As a result, there is a need to propose a novel mobile device with a novel antenna structure, so as to overcome the problems of the prior art.

BRIEF SUMMARY OF THE INVENTION

In a preferred embodiment, the disclosure is directed to a mobile device including a ground element, a metal frame, a feeding connection element, a first radiation element, a second radiation element, a capacitive element, a first shorting element, a second shorting element, and a third shorting element. The feeding connection element is coupled to a positive feeding point. The first radiation element is coupled to the feeding connection element. The second radiation element includes a first portion and a second portion. The feeding connection element is coupled through the second radiation element to a first connection point on the metal frame. The capacitive element is coupled between the first portion and the second portion. A second connection point on the metal frame is coupled through the first shorting element to a first grounding point on the ground element. A third connection point on the metal frame is coupled through the second shorting element to a second grounding point on the ground element. A fourth connection point on the metal frame is coupled through the third shorting element to a third grounding point on the ground element. An antenna structure is formed by the ground element, the metal frame, the feeding connection element, the first radiation element, the second radiation element, the capacitive element, the first shorting element, and the second shorting element. A positive electrode of a signal source is coupled to the positive feeding point, and a negative electrode of the signal source is coupled to a negative feeding point on the ground element, so as to excite the antenna structure.

In some embodiments, at least a portion of the metal frame substantially has an L-shape.

In some embodiments, the first radiation element substantially has a straight-line shape.

In some embodiments, the second radiation element substantially has an L-shape.

In some embodiments, the mobile device further includes a parasitic element. The parasitic element is coupled to a fourth grounding point on the ground element. The parasitic element is adjacent to the first radiation element.

In some embodiments, the parasitic element substantially has an L-shape.

In some embodiments, the antenna structure covers a first frequency band at 1575 MHz, a second frequency band from 2400 MHz to 2500 MHz, and a third frequency band from 5100 MHz to 5850 MHz.

In some embodiments, an inverted F-shaped resonant path is formed by the feeding connection element, the first radiation element, the second radiation element, the capacitive element, the metal frame, and the second shorting element. The inverted F-shaped resonant path is excited to generate the first frequency band.

In some embodiments, a first loop resonant path is formed by the feeding connection element, the second radiation element, the metal frame, the first shorting element, and the ground element. The first loop resonant path is excited to generate the second frequency band.

In some embodiments, a second loop resonant path is formed by the feeding connection element, the second radiation element, the metal frame, the second shorting element, and the ground element. The second loop resonant path is excited to generate the third frequency band.

DETAILED DESCRIPTION OF THE INVENTION

In order to illustrate the purposes, features and advantages of the invention, the embodiments and figures of the invention are described in detail below.

FIG. 1is a partial top view of a mobile device100according to an embodiment of the invention. The mobile device100may be a smartphone, a tablet computer, or a notebook computer. In the embodiment ofFIG. 1, the mobile device100at least includes a ground element110, a metal frame120, a feeding connection element130, a first radiation element140, a second radiation element150, a capacitive element157, a first shorting element160, a second shorting element170, and a third shorting element180. It should be understood that the mobile device100may further include other components, such as a processor, a touch control panel, a speaker, a battery module, and a housing, although they are not displayed inFIG. 1.

The ground element110, the feeding connection element130, the first radiation element140, the second radiation element150, the first shorting element160, the second shorting element170, and the third shorting element180may be all made of metal materials, such as copper, silver, aluminum, iron, or their alloys. The ground plane110may be a metal plane having a relatively large size, and it can provide a ground voltage. In some embodiments, the mobile device100further includes a dielectric substrate, such as a PCB (Printed Circuit Board) or an FR4 (Flame Retardant 4) substrate. Any one or more of the ground element110, the feeding connection element130, the first radiation element140, the second radiation element150, the capacitive element157, the first shorting element160, the second shorting element170, and the third shorting element180may be disposed on the dielectric substrate (not shown). In a preferred embodiment, an antenna structure is formed by the ground element110, the metal frame120, the feeding connection element130, the first radiation element140, the second radiation element150, the capacitive element157, the first shorting element160, and the second shorting element170.

The feeding connection element130may substantially have a straight-line shape. The feeding connection element130has a first end131and a second end132. The first end131of the feeding connection element130is coupled to a positive feeding point FP. The mobile device100may further includes a signal source199, which may be an RF (Radio Frequency) module. A positive electrode of the signal source199may be coupled to the positive feeding point FP, and a negative electrode of the signal source199may be coupled to a negative feeding point FN on the ground element110, so as to excite the aforementioned antenna structure. In other embodiments, the positions of the positive feeding point FP and the position of the negative feeding point FN may be exchanged with each other, without affecting the performance of the invention.

The first radiation element140may substantially have a straight-line shape. The first radiation element140may be substantially perpendicular to the feeding connection element130. The first radiation element140has a first end141and a second end142. The first end141of the first radiation element140is coupled to the second end132of the feeding connection element130. The second end142of the first radiation element140is an open end. In some embodiments, the first radiation element140further includes a rectangular widening portion145, which is substantially positioned at the second end142of the first radiation element140. The width of the rectangular widening portion145is greater than the width of the other portions of the first radiation element140. The rectangular widening portion145is configured to fine-tune the low-frequency resonant points of the aforementioned antenna structure. It should be noted that the rectangular widening portion145is an optional element. In other embodiments, the rectangular widening portion145is removed (i.e., adjustments are made such that the first radiation element140has an equal-width structure).

The second radiation element150may substantially have an L-shape. The feeding connection element130is coupled through the second radiation element150to a first connection point CP1on the metal frame120. The second radiation element150has a first end151and a second end152. The first end151of the second radiation element150is coupled to the second end132of the feeding connection element130. The second end152of the second radiation element150is coupled to the first connection point CP1. Specifically, the second radiation element150includes a first portion155and a second portion156. The first portion155may be substantially perpendicular to the feeding connection element130. The second portion156may be substantially parallel to the feeding connection element130. A T-shaped feeding connection structure may be formed by the feeding connection element130, the first radiation element140, and the first portion155of the second radiation element150. The capacitive element157may be a general capacitor, a chip capacitor, or a variable capacitor. The capacitive element157is coupled in series between the first portion155and the second portion156of the second radiation element150. The existence of the capacitive element157causes the aforementioned antenna structure to generate an additional resonant mode, thereby increasing the operation bandwidth of the antenna structure. The length of the second radiation element150(i.e., the total length of the first portion155and the second portion156) may be shorter than the length of the first radiation element140. For example, the length of the first radiation element140may be 2 to 4 times the length of the second radiation element150, but it is not limited thereto. In alternative embodiments, if the capacitive element157is a variable capacitor, the operation frequency band of the antenna structure will be adjustable.

The first shorting element160may substantially have a straight-line shape. A second connection point CP2on the metal frame120is coupled through the first shorting element160to a first grounding point GP1on the ground element110. The first shorting element160has a first end161and a second end162. The first end161of the first shorting element160is coupled to the first grounding point GP1. The second end162of the first shorting element160is coupled to the second connection point CP2.

The second shorting element170may substantially have a straight-line shape. A third connection point CP3on the metal frame120is coupled through the second shorting element170to a second grounding point GP2on the ground element110. The second shorting element170has a first end171and a second end172. The first end171of the second shorting element170is coupled to the second grounding point GP2. The second end172of the second shorting element170is coupled to the third connection point CP3. The length of the second shorting element170may be greater than the length of the first shorting element160. For example, the length of the second shorting element170may be 4 to 6 times the length of the first shorting element160, but it is not limited thereto.

The third shorting element180may substantially have a straight-line shape. A fourth connection point CP4on the metal frame120is coupled through the third shorting element180to a third grounding point GP3on the ground element110. The third shorting element180has a first end181and a second end182. The first end181of the third shorting element180is coupled to the third grounding point GP3. The second end182of the third shorting element180is coupled to the fourth connection point CP4. The length of the third shorting element180may be shorter than the length of the second shorting element170. For example, the length of the second shorting element170may be 4 to 6 times the length of the third shorting element180, but it is not limited thereto.

In some embodiments, one or more of the first shorting element160, the second shorting element170, and the third shorting element180are replaced with one or more 3D (Three-Dimensional) connection elements. The 3D connection elements are not necessarily disposed on the dielectric substrate. For example, each 3D connection element may be a metal pogo pin, a metal spring, or a metal screw.

At least a portion of the metal frame120may substantially have an L-shape. The metal frame120may be used as an exterior decorative element of the mobile device100. The so-called exterior decorative element is an element which covers the mobile device100and can be directly observed by eyes of a user. On the metal frame120, the first connection point CP1is substantially positioned between the second connection point CP2and the third connection point CP3, and the second connection point CP2is substantially positioned between the first connection point CP1and the fourth connection point CP4. The length from the first connection point CP1to the second connection point CP2may be greater than the length from the first connection point CP1to the third connection point CP3, and may also be greater than the length from the second connection point CP2to the fourth connection point CP4. Generally, the metal frame120includes a portion positioned between the second connection point CP2and the third connection point CP3, and the aforementioned portion is mainly excited to generate a radiation pattern of the antenna structure. In addition, on the ground element110, the negative feeding point FN is substantially positioned between the first grounding point GP1and the second grounding point GP2. The distance between the negative feeding point FN and the first grounding point GP1may be greater than the distance between the negative feeding point FN and the second grounding point GP2.

In some embodiments, the mobile device100further includes a parasitic element190, which may also be made of a metal material. The parasitic element190is adjacent to the first radiation element140(however, a separate gap may be formed between the parasitic element190and the first radiation element140). The parasitic element190may substantially have an L-shape. It should be noted that the term “adjacent” or “close” over the disclosure means that the distance (spacing) between two corresponding elements is shorter than a predetermined distance (e.g., 3 mm or shorter); however, the term “adjacent” or “close” usually does not include the two corresponding elements which directly touch each other (i.e., the aforementioned distance/spacing therebetween cannot be reduced to 0). The parasitic element190has a first end191and a second end192. The first end191of the parasitic element190is coupled to a fourth grounding point GP4on the ground element110. The second end192of the parasitic element190is an open end, which is adjacent to the second end142of the first radiation element140(or the rectangular widening portion145). The fourth grounding point GP4may be substantially positioned between the first grounding point GP1and the negative feeding point FN (or the second grounding point GP2). The fourth grounding point GP4may be very close to the first grounding point GP1. The parasitic element190is configured to increase the effective length of the low-frequency resonant path of the aforementioned antenna structure. It should be noted that the parasitic element190is an optional element. In other embodiments, adjustments are made such that the parasitic element190is removed.

FIG. 2is a complete top view of the mobile device100according to an embodiment of the invention.FIG. 1is considered as a partial enlargement ofFIG. 2(indicated by a dashed box). In the embodiment ofFIG. 2, the metal frame120is substantially a closed rectangular loop without any fracture, and the ground element110is substantially a rectangular metal plane. The ground element110is disposed inside the metal frame120. Such a no-fracture metal frame120can effectively enhance the structural robustness of the mobile device100. In other words, since there is no need to form any fracture points on the metal frame120, the incorporation of the antenna structure does not degrade the robustness of the mobile device100. Besides the first grounding point GP1, the second grounding point GP2, and the third grounding point GP3, the metal frame120may be further coupled through one or more shorting elements to one or more grounding points GPN on the ground element110. The aforementioned grounding points GPN are arranged for suppressing undesired resonant modes. The positions and the number of the grounding points GPN and the corresponding shorting elements are adjustable according to different requirements. It should be noted that the third shorting element180and the third grounding point GP3are configured to prevent the other portions of the metal frame120from generating resonant currents and interfering with the radiation performance of the antenna structure. If the third shorting element180and the third grounding point GP3were removed, the operation frequency band of the antenna structure might be seriously shifted.

FIG. 3Ais a diagram of VSWR (Voltage Standing Wave Ratio) of the antenna structure of the mobile device100according to an embodiment of the invention. The horizontal axis represents the operation frequency (MHz), and the vertical axis represents the VSWR. According to the measurement ofFIG. 3A, when receiving or transmitting wireless signals, the antenna structure of the mobile device100can cover a first frequency band FB1, a second frequency band FB2, and a third frequency band FB3. The first frequency band FB1may be at or around 1575 MHz. The second frequency band FB2may be from about 2400 MHz to about 2500 MHz. The third frequency band FB3may be from about 5100 MHz to about 5850 MHz. Accordingly, the antenna structure of the mobile device100can support at least the wideband operations of GPS (Global Positioning System) and WLAN (Wireless Local Area Networks) 2.4 GHz/5 GHz.

FIG. 3Bis a diagram of VSWR of the antenna structure of the mobile device100without the capacitive element157. The horizontal axis represents the operation frequency (MHz), and the vertical axis represents the VSWR. By comparingFIG. 3AwithFIG. 3B, if the capacitive element157were removed from the mobile device100, the antenna structure could not cover the first frequency band FB1. Therefore, the existence of the capacitive element157causes the antenna structure to further generate a GPS resonant mode. In some embodiments, the capacitance of the capacitive element157is from 0.6 pF to 1 pF, and is preferably 0.8 pF. The above range of capacitance helps to maximize the operation bandwidth of the first frequency band FB1.

Specifically, the resonant mechanisms and operation principles of the antenna structure of the mobile device100will be illustrated in the following embodiments ofFIG. 4A,FIG. 4B, andFIG. 4C.

FIG. 4Ais a diagram of resonant currents of the antenna structure of the mobile device100when the antenna structure operates in the first frequency band FB1, according to an embodiment of the invention (the dashed arrows represent the possible flowing directions of the resonant currents). In the embodiment ofFIG. 4A, an inverted F-shaped resonant path410is formed by the feeding connection element130, the first radiation element140, the second radiation element150, the capacitive element157, the metal frame120(especially for the portion of the metal frame120between the first connection point CP1and the third connection point CP3), and the second shorting element170. The inverted F-shaped resonant path410is excited to generate the first frequency band FB1.

FIG. 4Bis a diagram of resonant currents of the antenna structure of the mobile device100when the antenna structure operates in the second frequency band FB2, according to an embodiment of the invention (the dashed arrows represent the possible flowing directions of the resonant currents). In the embodiment ofFIG. 4B, a first loop resonant path420is formed by the feeding connection element130, the second radiation element150, the metal frame120(especially for the portion of the metal frame120between the first connection point CP1and the second connection point CP2), the first shorting element160, and a first edge111of the ground element110(the first edge111is positioned between the first grounding point GP1and the negative feeding point FN). The first loop resonant path420is excited to generate the second frequency band FB2. It should be noted that the parasitic element190is considered as an extension portion of the first loop resonant path420, which helps to further decrease the central frequency of the second frequency band FB2. Furthermore, the capacitive element157is considered as a short-circuited path in the second frequency band FB2.

FIG. 4Cis a diagram of resonant currents of the antenna structure of the mobile device100when the antenna structure operates in the third frequency band FB3, according to an embodiment of the invention (the dashed arrows represent the possible flowing directions of the resonant currents). In the embodiment ofFIG. 4C, a second loop resonant path430is formed by the feeding connection element130, the second radiation element150, the metal frame120(especially for the portion of the metal frame120between the first connection point CP1and the third connection point CP3), the second shorting element170, and a second edge112of the ground element110(the second edge112is positioned between the second grounding point GP2and the negative feeding point FN). The second loop resonant path430is excited to generate the third frequency band FB3. Furthermore, the capacitive element157is considered as a short-circuited path in the third frequency band FB3.

In some embodiments, the element sizes of the mobile device100are as follows. The total length of the feeding connection element130and the first radiation element140(i.e., the total length from the first end131through the second end132and the first end141to the second end142) may be substantially equal to 0.25 wavelength (λ/4) of the central frequency of the first frequency band FB1. The total length of the first loop resonant path420may be substantially equal to 0.5 wavelength (λ/2) of the central frequency of the second frequency band FB2. The total length of the second loop resonant path430may be substantially equal to 0.5 wavelength (λ/2) of the central frequency of the third frequency band FB3. The above ranges of element sizes are calculated and obtained according to many experiment results, and they help to optimize the operation frequency band and the impedance matching of the antenna structure of the mobile device100.

The invention proposes a novel antenna structure. When the antenna structure is applied to a mobile device including a metal frame, the metal frame is considered as an extension portion of the antenna structure, and therefore such a design can effectively prevent the metal frame from negatively affecting the communication quality of the mobile device. Furthermore, the metal frame is used as an effective radiation element for reducing the total antenna size and increasing the antenna operation bandwidth. It should also be noted that the invention can improve the appearance of the mobile device without opening any antenna windows. In conclusion, the invention has the advantages of small device size, wide bandwidth, and beautiful device appearance, and it is suitable for application in a variety of mobile communication devices.

Note that the above element sizes, element shapes, and frequency ranges are not limitations of the invention. An antenna designer can adjust these settings or values according to different requirements. It should be understood that the mobile device and the antenna structure of the invention are not limited to the configurations ofFIGS. 1-4. The invention may merely include any one or more features of any one or more embodiments ofFIGS. 1-4. In other words, not all of the features shown in the figures should be implemented in the mobile device and the antenna structure of the invention.

It will be apparent to those skilled in the art that various modifications and variations can be made in the invention. It is intended that the standard and examples be considered as exemplary only, with the true scope of the disclosed embodiments being indicated by the following claims and their equivalents.