Field of the invention

The present disclosure relates to the field of antenna technique and particularly to an antenna assembly for a mobile terminal.

Background of the invention

A mobile terminal has increasingly complicated functions and has to comply with a variety of communication protocols and standards while its figure being increasingly miniaturized and ultra-thinned. These trends result in an increasingly small space available for an antenna element in the mobile terminal on one hand and an increasing demand for the performance of the antenna which only occupies a limited space on the other hand. That is to say, an antenna system has to operate with good performance in more frequency bands or at a higher bandwidth. Unfortunately the radiation performance of the antenna which is a frequency-dependent element is proportionate to the size of the space occupied by the antenna. The narrow space will restrain the radiation performance of the antenna and make it difficult for the antenna to satisfy a performance requirement of the system.

The mobile terminal typically includes several antennas independent from each other. Particularly in a mobile phone terminal, these antennas are commonly divided functionally into a primary antenna and an auxiliary antenna, wherein the primary antenna is an antenna to support a communication protocol of a cellular system, e.g., GSM, CDMA, WCDMA, etc. The auxiliary antenna may be an antenna to support signals in various frequency bands of Global Positioning System (GPS), Bluetooth, Wireless Local Area Network (WLAN), mobile television, Frequency Modulation (FM) broadcast, etc., or may be a secondary antenna to support Multiple-Input Multiple-Output (MIMO) or signal diversity. Since a specific space internal to the mobile terminal is occupied by the respective antennas, the space occupied by the entire antenna system is considerable. It is rather difficult for each antenna element to achieve an excellent level of radiation performance due to limitations of the occupancy area, the height, the headroom and other factors thereof, and influences of a casing and other components, thus the communication quality of the system is eventually influenced.

Furthermore in the field of mobile terminals especially mobile phone terminals, a metal casing earns an increasing attention of consumers due to a good texture and the durability thereof. Using metal material to make the casing of a mobile phone has become a trend. A common practice is to electrically connect the metal casing with the ground of a circuit board in the mobile terminal so as to make it become a part of the ground of the system. In order to prevent a signal of a built-in antenna from being shielded by the body of the metal casing, the metal casing is bored or slotted in the place corresponding to the built-in antenna to enable the radiation of the signal of the antenna. This solution generally may bring a significant adverse influence upon the performance of the antenna due to the large metal component added around the antenna.

Summary of the invention

A fundamental idea of the invention is to use an electrically conductive casing of a mobile terminal as a radiating body of an antenna thereof. By designing the figure, the location of a feed port and the excitation mode, the electrically conductive casing may function as a radiating body of an antenna for radio communication in one or more frequency bands.

In the invention, a structure like a micro-strip patch antenna is formed between the metal casing and a ground in the mobile terminal.

The micro-strip patch antenna is an antenna formed by affixing a conductor sheet onto a dielectric substrate with a conductor ground. Power is fed in the proper place over a micro-strip line or a coaxial cable so as to have a radio frequency electromagnetic field excited between the conductor sheet and the ground, and radiated through a gap between the periphery of the conductor sheet and the ground. The micro-strip patch antenna has a good radiation performance and enjoys easy conformance, flexible formation, easy circular polarization and dual polarization, operability in multiple frequency bands and other advantages. However the micro-strip patch antenna is rarely adopted in a general mobile terminal due to considerable spatial occupancy thereof. Following the foregoing principle, a structure like a micro-strip patch antenna is formed between a metal casing and a ground of a printed circuit board in a mobile terminal according to the invention. A frequency band and a mode thereof can be achieved by designing the shape of the casing and the location and mode of the feeding. In an existing design, there is also a solution in which an antenna is integrated on an exterior component of a mobile terminal, for example, a part of a metal frame of the mobile terminal functions is used as an antenna. However the antenna adopted in such design is a traditional antenna form in the mobile terminal such as a monopole antenna, a loop antenna, an Inverted F Antenna (IFA), etc.. Furthermore the casing in such design is of a plastic material except for the metal material embedded in an area of the frame as a radiation element of the antenna.

In an embodiment of the invention, there is provided an antenna assembly for a mobile terminal, which includes: a radiation element integrated with a cover of the mobile terminal, consisted of electrically conductive material and including at least one antenna port formed thereon; wherein the antenna port is capable of exciting the radiation element to operate in a plurality of frequency bands when the cover is fastened to the mobile terminal.

In an embodiment of the invention, the antenna assembly for a mobile terminal further includes a ground of a printed circuit board in the mobile terminal. A structure like a micro-strip patch antenna is formed by the radiation element and the ground.

In an embodiment of the invention, the antenna assembly for a mobile terminal further includes at least one feeding element in one-to-one correspondence with the antenna port, wherein the feeding element and the antenna port are connected in a contacting or non-contacting manner.

In an embodiment of the invention, the plurality of frequency bands of the antenna assembly for a mobile terminal include any combination of frequency bands corresponding to communication protocols of GPS, Bluetooth, WiFi, frequency modulation broadcast, mobile television, GSM, CDMA, WCDMA, TS-SCDMA, LTE and WiMAX.

In another embodiment of the invention, in the antenna assembly for a mobile terminal, the antenna port on the radiation element includes at least one multi-band antenna port which is capable of exciting the radiation element to operate in a subset of the plurality of frequency bands, which includes at least two of the plurality of frequency bands.

In another embodiment of the invention, in the antenna assembly for a mobile terminal, the antenna port on the radiation element includes a plurality of antenna ports, each of which is capable of exciting the radiation element to operate in a different frequency band.

In an embodiment of the invention, there is provided an antenna assembly for a mobile terminal, which includes: a radiation element integrated with a cover of the mobile terminal, consisted of electrically conductive material and including a plurality of antenna ports formed thereon, wherein at least two of the plurality of antenna ports are capable of exciting the radiation element to operate in the same frequency band when the cover is fastened to the mobile terminal.

In an embodiment of the invention, the antenna assembly for a mobile terminal further includes a ground of a printed circuit board in the mobile terminal. A structure like a micro-strip patch antenna is formed by the radiation element and the ground.

In an embodiment of the invention, the antenna assembly for a mobile terminal further includes a plurality of feeding elements in one-to-one correspondence with the plurality of antenna ports, wherein the feeding elements and the antenna ports are connected in a contacting or non-contacting manner.

In an embodiment of the invention, at least two of the plurality of antenna ports of the antenna assembly for a mobile terminal are capable of exciting the radiation element to operate in orthogonal modes in the same frequency band.

In another embodiment of the invention, the exterior surface of the radiation element of the antenna assembly for a mobile terminal is further covered with an electrically isolated layer to further alleviate an adverse influence upon radio communication performance due to a contact of a user with the radiating element.

In another embodiment of the invention, the electrically conductive material adopted for the radiation element in the antenna assembly for a mobile terminal includes metal, electrically conductive plastic or electrically conductive rubber.

In an embodiment of the invention, there is provided a mobile terminal including the antenna assembly according to any one of the foregoing embodiments.

In an embodiment of the invention, the mobile terminal further includes a gating element (a switching element, a duplexer or a multiplexer) connected to the multi-band antenna port

As can be seen from the disclosed embodiments of the invention, the casing is excited at a plurality of different locations so that the casing antenna can generate resonance covering a plurality of radio communication frequency bands with excellent radiation efficiency in the respective resonance frequency bands. An excellent degree of isolation can be achieved between the respective antenna ports, and radio communication of multiple protocols can be performed concurrently. A high efficiency of radiation in a free space can be easily achieved using the metal casing as a radiation body of the antenna due to a large size of the casing. Also this design can reduce the number of separate antennas in an existing mobile terminal and thus further miniaturize the mobile terminal.

Brief description of drawings

Other features, objects and advantages of the invention will become more apparent upon reading the following detailed description of non-limiting embodiments with reference to the drawings:

Fig. l illustrates an exploded structural diagram of a part of a mobile terminal according to an embodiment of the invention;

Fig.2a illustrates an exploded structural diagram of a part of a mobile terminal according to another embodiment of the invention;

Fig.2b illustrates a plan view of a radiation element in the mobile terminal in

Fig.2a;

Fig.2c illustrates echo loss curves of respective antenna ports in the mobile terminal illustrated in Fig.2a;

Fig.2d illustrates transmission coefficient curves of the respective antenna ports in the mobile terminal illustrated in Fig.2a; Fig.3 illustrates an exploded structural diagram of a part of a mobile terminal according to another embodiment of the invention;

Fig.4 illustrates a logic structural diagram of a part of a mobile terminal according to another embodiment of the invention;

Fig.5 illustrates an exploded structural diagram of a part of a mobile terminal according to another embodiment of the invention;

Fig.6a illustrates a plan view of a radiation element in an antenna assembly according to another embodiment of the invention; and

Fig.6b illustrates echo loss and transmission coefficient curves of antenna ports illustrated in Fig.6a.

Identical or like reference numerals will denote corresponding features throughout the figures in the drawings.

Detailed description of embodiments

A mobile terminal as referred to in the invention is intended to encompass any portable or hand-held mobile device capable of communication with another device via one or more specific radio protocols or standards, for example (but not limited to), a mobile phone, a smart mobile phone, a Personal Digital Assistant (PDA), a portable computer, a portable GPS terminal, etc.

Fig. l illustrates an exploded structural diagram of a part of a mobile terminal 10 according to an embodiment of the invention. As illustrated, the mobile terminal 10 in this embodiment includes a front panel 103, a Printed Circuit Board (PCB) 102, an electrically conductive back cover 101 , an electrically non-conductive casing 104 and a separate built-in antenna 105. For example (but not limited to), a battery can be at least partially between the back cover 101 and the printed circuit board 102.

A planar radiation element is integrated on the back cover 101 as a part of an antenna assembly. In some examples, the entire back cover 101 can function as a radiating element. Typically the radiation element is constituted of an electrically conductive material, e.g., metal, alloy, electrically conductive plastic or electrically conductive rubber. A feeding element 151 and a corresponding signal processing module 11 1, a feeding element 152 and a corresponding signal processing module 1 12, and a feeding element 153 and a corresponding signal processing module 113 are further arranged on the printed circuit board 102. When the back cover 101 is fastened to the mobile terminal 10, each of the feeding elements 151 , 152 and 153 can feed via respective antenna ports on the radiation element to excite the radiation element to operate in at least one frequency band. Thus a structure like a micro-strip patch antenna is formed by the radiation element integrated with the back cover 101 and the ground of the printed circuit board 102. In this example, the feeding element 151 corresponds to a mobile television frequency band to support a mobile multimedia service, the operating frequency band of the feeding element 152 corresponds to the Bluetooth frequency band, and the operating frequency band of the feeding element 153 corresponds to the GPS frequency band.

In view of some design considerations, the presence of the separate built-in antenna 105 is still necessary. In this case, the electrically non-conductive casing 104 is adopted for a part of the area of the mobile terminal 10. The casing 104 is typically of a plastic material so that the separate built-in antenna 105 radiates a radio signal effectively without being shielded.

In respective embodiments of the invention, the operating frequency bands corresponding to the respective feeding elements (or antenna ports) can include one or more of frequency bands corresponding to communication protocols of GPS, Bluetooth, WiFi, frequency modulation broadcast, a mobile television UHF frequency band, an S band, GSM, CDMA, WCDMA, TS-SCDMA, LTE and WiMAX. The feeding elements include a necessary matching circuit for transporting a signal effectively to the antenna ports.

Fig.2a illustrates an exploded structural diagram of a part of a mobile terminal 20 according to another embodiment of the invention. The mobile terminal 20 in this embodiment includes a printed circuit board 202 and a radiation element 206 integrated on a cover (not illustrated).

The radiation element 206 includes antenna ports 261 and 262.

The printed circuit board 202 includes feeding elements 251 and 252 and the corresponding signal processing modules (not illustrated). A traditional antenna 208 is arranged on one end of the printed circuit board 202 in an area unshielded by the radiation element 206. For example, the antenna 208 is but will not be limited to a monopole antennal, a PIFA antenna, etc.

The feeding element 251 corresponds to the antenna port 261 and excites the radiation element 206 to operate by feeding the antenna port 261. The feeding element 252 corresponds to the antenna port 262 and excites the radiation element 206 to operate by feeding the antenna port 262. Thus a structure like a micro-strip patch antenna is formed by the radiation element 206 integrated with the cover and the ground of the printed circuit board 202.

A contracting connection or a non-contacting connection can be adopted between the feeding element 251 and the antenna port 261 and between the feeding element 252 and the antenna port 262. For a contacting connection, the form of a pogo pine or a spring clip can be adopted for the feeding elements. For a non-contacting connection, the feeding elements and the corresponding antenna ports can be coupled, for example (but not limited to), through a capacitor. In some other embodiments of the invention, the feeding elements can alternatively be arranged on the cover.

Fig.2b illustrates a plan view of the radiation element 206 in the mobile terminal 20 in Fig.2a; Fig.2c illustrates echo loss curves of the respective antenna or antenna ports in the mobile terminal 20 illustrated in Fig.2a; and Fig.2d illustrates transmission coefficient curves of the respective antenna or antenna ports in the mobile terminal 20 illustrated in Fig.2a.

As illustrated in Fig.2b, the radiation element 206 is a rectangle with the size of 45mm (along the x axis)* 75mm (along the y axis). With the bottom right corner of the radiation element 206 as illustrated being the origin of coordinates, the coordinates of the central location of the antenna port 261 are (43mm, 22mm), and the coordinates of the central location of the antenna port 262 are (22.5mm, 57mm). The echo loss (vs. frequency) curve of the antenna port 261 is illustrated as the curve in Fig. 2c marked with circles, and the transmission coefficient (vs. frequency) curve thereof is illustrated as the curve in Fig.2d marked with circles. The echo loss curve of the antenna port 262 is illustrated as the curve in Fig.2c marked with triangles and the transmission coefficient curve thereof is illustrated as the curve in Fig.2d marked with triangles. The echo loss curve and the transmission coefficient curve of the antenna 208 are illustrated respectively as the unmarked curves in Fig.2c and Fig.2d. As illustrated, the operating frequency corresponding to the antenna port 261 includes a Bluetooth frequency band or a WiFi frequency band around 2450MHz; the operating frequency corresponding to the antenna port 262 includes a GPS frequency band around 1572.42MHz; and the operating frequency corresponding to the traditional antenna 208 includes various frequency bands of a cellular system, such as the GSM850MHz frequency band, the EGSM900MHz frequency band, the DCS 1800MHz frequency band, the PCS 1900MHz frequency band and WCDMA frequency bands

(1710-1755MHz/2110-2155MHz/1920-1980MHz/2110-2170MHz). As can be seen from Fig.2c, corresponding echo losses in all the foregoing frequency bands are below -6dB, and as can be een from Fig.2d, there is a degree of isolation above 15dB between the respective ports, both of which show excellent and reliable operating performance of this design solution.

In order to avoid or alleviate an adverse influence upon the performance of the mobile terminal 20 due to a physical contact of a user with the radiation element 206, the exterior surface of the radiation element 206 can optionally be further covered with an electrically insulated layer.

In some other embodiments of the invention, as a part of the antenna assembly, the radiation element integrated with the cover of the mobile terminal is shaped variously, for example, in the shape of a triangle, a quadrangle, a circle, an ellipse, etc., and a quasi-polygon rounded at corners thereof. In some other embodiments, there are hollow-carved parts in various shapes or patterns on the radiation element integrated with the cover of the mobile terminal, and typically these hollow-carved parts are consisted of or filled with a electrically non-conductive material. The foregoing various designs for the shape of the radiation element are intended to satisfy requirements of various operating bands of the antenna and the combinations thereof.

Fig.3 illustrates an exploded structural diagram of a part of a mobile terminal 30 according to a further embodiment of the invention. As illustrated, the mobile terminal 30 in this embodiment includes a front panel 303, a printed circuit board 302 and a back cover 301. For example (but not limited to), a battery can be at least partially between a back cover 301 and a printed circuit board 302.

In this embodiment, the body of the back cover 301 functions as a radiation element and forms a structure like a micro-strip patch antenna together with the ground of the printed circuit board 302. In order to provide an antenna with a plurality of resonance frequencies to support a plurality of operating bands, the radiation element can be designed to have a shape in a complex pattern thereon, for example (but not limited to), hollow-carved parts in a strip shape and in an E shape as illustrated.

A feeding element 351 and a corresponding signal processing module or circuit 311 are arranged on the printed circuit board 302. For example(but not limited to), when the back cover 301 is fastened to the mobile terminal 30, the feeding element 351 feeds a corresponding antenna port on the back cover 301 so that the antenna 301 can operate in a plurality of frequency bands of a cellular system. Of course, other antenna ports and feeding elements can further be added so that the cover can operate concurrently in a frequency band of another communication protocol to thereby take the place of all of separate antenna elements in the mobile terminal and perform all of antenna functions.

In some embodiments of the invention, there are a plurality of antenna ports on the radiation element integrated with the cover of the mobile terminal. There is at least one multi-band antenna port among the plurality of antenna ports. The multi-band antenna port is capable of exciting the radiation element to operate in at least two frequency bands which are a subset of all the operating frequency bands of the radiating element. In an embodiment, the operating frequency corresponding to the multi-band antenna port includs a GPS frequency band, a mobile television UHF frequency band, WiFi and a Bluetooth frequency band. In this embodiment, the mobile terminal further includes a multiplexer connected to the multi-band antenna port, and the multiplexer is connected to one or more signal processing modules to process a GPS signal, a mobile television signal, a WiFi signal or a Bluetooth signal respectively.

Fig.4 illustrates a logic structural diagram of a part of a mobile terminal according to an embodiment of the invention. In this embodiment, the radiation element integrated on the cover of the mobile terminal includes a multi-band antenna port 451 connected to the feeding element 411 on the printed circuit board. As mentioned above, direct contacting or non-contacting manner can be adopted for the connection. The feeding element 411 is connected to a gating element 460 connected to a plurality of signal processing modules or circuits 461 and 462 or like. The multi-band antenna port 451 is capable of exciting the radiation element to operate in a plurality of frequency bands, and each of the signal processing modules or the circuits 461 and 462 is configured to process the signal in one of the operating bands. Specifically the gating element 460 includes filter elements in one-to-one correspondence with the respective signal processing modules or circuits 461 and 462 to select a signal at an operating frequency corresponding to the respective signal processing modules or circuits. In different embodiments, the gating element can be a switching element, a duplexer or a multiplexer respectively dependent upon practical applications and design requirements.

In some other embodiments of the invention, there are a plurality of single-band antenna ports on the radiation element integrated with the cover of the mobile terminal. These single-band antenna ports are capable of exciting the radiation element respectively to operate in different frequency bands. In an embodiment, there are four single-band antenna ports on the radiation element integrated with the cover of the mobile terminal, wherein one port corresponds to an operating frequency band which is a GPS frequency band and is connected to a GPS signal processing module on the printed circuit board. Another port corresponds to an operating frequency band which is a Bluetooth frequency band and is connected with a Bluetooth signal processing module on the printed circuit board. Yet another port corresponds to an operating frequency band which is a frequency modulation broadcast frequency band and is connected with a frequency modulation broadcast signal processing module on the printed circuit board. The remaining port corresponds to an operating frequency band which is a WiFi frequency band and is connected with a WiFi signal processing module on the printed circuit board.

In some other embodiments, there are a plurality of single-band antenna ports on the radiation element integrated with the cover of the mobile terminal, and the plurality of ports correspond to the operating frequency bands which are the same frequency band.

Fig.5 illustrates an exploded structural diagram of a part of a mobile terminal 50 according to another embodiment of the invention. The mobile terminal 50 in this embodiment includes a printed circuit board 502 and a radiation element 506 integrated on a cover (not illustrated). A structure like a micro-strip patch antenna is formed by the radiation element 506 and the ground of the printed circuit board 502.

There are a first antenna port 561 and a second antenna port 562 formed on the radiation element 506. There are feeding elements 551 and 552, connected respectively to the first antenna port 561 and the second antenna port 562, and corresponding signal processing modules (not illustrated) on the printed circuit board 502.

Both the first antenna port 561 and the second antenna port 562 are capable of exciting the radiation element 506 to operate in a first frequency band which can be a frequency band used in any Multiple-Input Multiple-Output (MIMO)-enabled radio communication protocol, for example (but not limited to), the WiFi frequency band of 2400~2483MHz.

With an elaborate design of the shape and the size of the radiation element 506 and the locations of the first antenna port 561 and the second antenna port 562, the radiation element 506 can be excited to generate two orthogonal modes with the same resonance frequency. For example (but not limited to), the radiation element 506 can be a square or approximately a square, and the first antenna port 561 and the second antenna port 562 can be located respectively on two central axes of the radiation element 506 next to an edge.

In an embodiment of the invention, an antenna assembly for a mobile terminal includes a radiation element integrated with a cover of the mobile terminal and consisted of an electrically conductive material; and when the cover is fastened to the mobile terminal, a structure like a micro-strip patch antenna is formed by the radiation element and the ground of a printed circuit board in the mobile terminal with the distance between the radiation element and the circuit printed board being 5mm. Fig.6a illustrates a plan view of the radiation element 606 in an antenna assembly of this embodiment. As illustrated, the radiation element 606 is sized 55mm* 54mm and includes a first antenna port 661 and a second antenna port 662 thereon. With the bottom left corner of the radiation element 606 as illustrated being origin of coordinate, the coordinates of the central location of the antenna port 661 are (27.5mm, 14mm), and the coordinates of the central location of the antenna port 662 are (19mm, 29mm). In this case, a mode excited via the antenna port 661 is approximately a TMoi mode polarized in the y direction of a micro-strip patch antenna, and a mode excited via the antenna port 662 is a TMio mode polarized in the x direction, and these two modes are orthogonal to each other. Fig.6b illustrates performance curves of the antenna ports illustrated in Fig.6a. The echo loss I S 1 11 curve of the antenna port 661 is illustrated as the curve marked with triangles, the echo loss |Sn | curve of the antenna port 662 is illustrated as the curve marked with circles, and the transmission coefficient |S ₂₁ | curve between the antenna ports 661 and 662 is illustrated as the unmarked curve. As illustrated, in-band echo losses of both the antenna ports 661 and 662 are below -6dB, and there is a degree of isolation above 20dB from each other, in the frequency band range (2400~2483MHz) of a wireless local area network. Such excellent performance can satisfy high degree-of-isolation and high-efficiency requirements of an MIMO system upon a mutli-antenna system.

Those skilled in the art shall appreciate that the foregoing embodiments are illustrative but not limiting. Different technical features appearing in different embodiments can be combined to advantage. Those skilled in the art shall appreciate and implement other variant embodiments of the disclosed embodiments upon reviewing the drawings, the description and the claims. In the claims, the term "comprising" will not preclude another means or step(s); the indefinite article "a/an" will not preclude plural; and the terms "first", "second", etc., are intended to designate a name but not to represent any specific order. Any reference numerals in the claims shall not be construed as limiting the scope of the invention. Functions of a plurality of parts appearing in a claim can be performed by a separate module in hardware or software, and a function of one part can be performed by a plurality of different modules in hardware or software. Some technical features appearing in different dependent claims will not mean that these technical features can not be combined to advantage.