Multiband antenna structure and wireless communication device using same

The subject matter herein generally relates to an antenna structure and a wireless communication device using the antenna structure.

Metal housings, for example, metallic backboards, are widely used for wireless communication devices, such as mobile phones and personal digital assistants (PDAs). Antennas are also important components in wireless communication devices for receiving and transmitting wireless signals at different frequencies, such as signals in Long Term Evolution Advanced (LTE-A) frequency bands. However, when the antenna is located in the metal housing, the antenna signals are often shielded by the metal housing. This can degrade the operation of the wireless communication device.

Therefore, there is room for improvement within the art.

Implementations of the present disclosure will now be described, by way of example only, with reference to the attached figures.

FIG. 1 is an isometric view of an embodiment of a wireless communication device using an antenna structure.

FIG. 2 is an assembled, isometric view of the wireless communication device of FIG. 1 .

FIG. 3 is a circuit diagram of the antenna structure of FIG. 1 .

FIG. 4 is a circuit diagram of a switching circuit of the antenna structure of FIG. 1 .

FIG. 5A to FIG. 5F are schematic plan views of the antenna structure of FIG. 3 .

FIG. 6 is a scattering parameter graph when the antenna structure of FIG. 1 works at a Long Term Evolution Advanced (LTE-A) low frequency operating mode.

FIG. 7 is a total radiating efficiency graph when the antenna structure of FIG. 1 works at the LTE-A low frequency operating mode.

FIG. 8 is a scattering parameter graph when the antenna structure of FIG. 1 works at LTE-A middle and high frequency operating modes.

FIG. 9 is a total radiating efficiency graph when the antenna structure of FIG. 1 works at the LTE-A middle and high frequency operating modes.

It will be appreciated that for simplicity and clarity of illustration, where appropriate, reference numerals have been repeated among the different figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein can be practiced without these specific details. In other instances, methods, procedures, and components have not been described in detail so as not to obscure the related relevant feature being described. Also, the description is not to be considered as limiting the scope of the embodiments described herein. The drawings are not necessarily to scale and the proportions of certain parts have been exaggerated to better illustrate details and features of the present disclosure.

Several definitions that apply throughout this disclosure will now be presented.

The term “substantially” is defined to be essentially conforming to the particular dimension, shape, or other feature that the term modifies, such that the component need not be exact. For example, “substantially cylindrical” means that the object resembles a cylinder, but can have one or more deviations from a true cylinder. The term “comprising,” when utilized, means “including, but not necessarily limited to”; it specifically indicates open-ended inclusion or membership in the so-described combination, group, series, and the like.

The present disclosure is described in relation to an antenna structure and a wireless communication device using same.

FIG. 1 illustrates an embodiment of a wireless communication device 200 using an antenna structure 100 . The wireless communication device 200 can be, for example, a mobile phone or a personal digital assistant. The antenna structure 100 can receive and transmit wireless signals.

In this embodiment, the wireless communication device 200 further includes a substrate 21 and an electronic element. The substrate 21 is a printed circuit board (PCB) and is made of dielectric material, for example, epoxy resin glass fiber (FR4) or the like. The substrate 21 includes a first feed point 211 , a first ground point 212 , a second feed point 213 , and a second ground point 215 .

The first feed point 211 and the second feed point 213 are configured to supply current to the antenna structure 100 . The first ground point 212 and the second ground point 215 are configured for grounding the antenna structure 100 .

The electronic element 23 can be, for example, a Universal Serial Bus (USB) module. The electronic element 23 is positioned on the substrate 21 between the first feed point 211 and the second ground point 215 .

The antenna structure 100 includes a housing 10 , a first feed portion 13 , a radiator 13 , a first ground portion 15 , a second feed portion 16 , and a second ground portion 17 .

The housing 10 houses the wireless communication device 200 and can be made of metallic material. The housing 10 includes a backboard 101 and a side frame 102 . The backboard 101 and the side frame 102 can be integrally formed with each other. The side frame 102 is positioned to surround a periphery of the backboard 101 . The side frame 102 and backboard 101 form a receiving space 103 . The receiving space 103 can receive the substrate 21 , a processing unit, or other electronic components or other modules (not shown).

In this embodiment, the side frame 102 includes an end portion 104 , a first side portion 105 , and a second side portion 106 . The first side portion 105 and the second side portion 106 are parallel to, and spaced apart from, each other. The end portion 104 has first and second ends. The first side portion 105 is connected to the first end of the first frame 111 and the second side portion 106 is connected to the second end of the end portion 104 . In this embodiment, the end portion 104 can be a top portion or a bottom portion of the wireless communication device 200 .

The housing 10 further defines a through hole 107 , a slot 108 (shown in FIG. 2 ), a first gap 109 , a second gap 110 , and a third gap 111 . In this embodiment, the through hole 107 is defined in, and passes through, the end portion 104 . The through hole 107 corresponds to the electronic element 23 . Thus, the electronic element 23 can be partially exposed through the through hole 107 . For example, a USB plug device can be inserted into the through hole 107 to be electrically connected to the electronic element 23 .

In FIG. 2 and FIG. 3 , the slot 108 is shown as substantially U-shaped. The slot 108 is defined on the backboard 101 adjacent to the end portion 104 . The first gap 109 , the second gap 110 , and the third gap 111 are all defined by the side frame 102 . The first gap 109 is defined by the end portion 104 adjacent to the first side portion 105 . The second gap 110 is defined by the first side portion 105 adjacent to the end portion 104 . The third gap 111 is defined by the second side portion 106 adjacent to the end portion 104 .

The first gap 109 , the second gap 110 , and the third gap 111 are all in communication with the slot 108 and extend to cut across the side frame 102 . The housing 10 is divided into three portions by the first gap 109 , the second gap 110 , and the third gap 111 . The three portions are a coupling portion A 1 , a radiating portion A 2 , and a grounding portion A 3 .

The coupling portion A 1 is formed by a first portion of the side frame 102 between the first gap 109 and the second gap 110 . The radiating portion A 2 is formed by a second portion of the side frame 102 between the first gap 109 and the third gap 111 . The grounding portion A 3 is formed by portions of the side frame 102 not associated with the coupling portion A 1 and the radiating portion A 2 . The grounding portion A 3 is grounded.

In this embodiment, the slot 108 , the first gap 109 , the second gap 110 , and the third gap 111 are all filled with insulating material, for example, plastic, rubber, glass, wood, ceramic, or the like. The through hole 107 is not filled because it has to allow a plug device to pass through.

In other embodiments, the slot 108 may be other than U-shaped. For example, the slot 108 can be a straight strip, an oblique line, or a meander.

In this embodiment, the slot 108 is defined on the backboard 101 adjacent to the end portion 104 and extends to an edge of the end portion 104 . The coupling portion A 1 and the radiating portion A 2 are completely formed by the end portion 104 , a portion of the first side portion 105 , and a portion of the second side portion 106 . That is, the coupling portion A 1 and the radiating portion A 2 are formed by a portion of the side frame 102 .

In other embodiments, a position of the slot 108 can be changed. For example, the slot 108 can be defined on a middle portion of the backboard 101 . The coupling portion A 1 and the radiating portion A 2 are formed by a portion of the side frame 102 and a portion of the backboard 101 .

In other embodiments, a location of the slot 108 is not limited to be the backboard 101 and the slot 108 can be defined on the end portion 104 .

In this embodiment, the first feed portion 11 and the radiator 13 are both positioned in the receiving space 103 . The first feed portion 11 and the radiator 13 are positioned in a receiving space (not labeled) beginning at the coupling portion A 1 and ending at the first gap 109 and the second gap 110 .

The first feed portion 11 can be a screw, a microstrip line, a probe, or other connecting structures. One end of the first feed portion 11 is electrically connected to the radiator 13 . Another end of the first feed portion 11 is electrically connected to the first feed point 211 to supply current to the radiator 13 .

The radiator 13 can be substantially L-shaped. The radiator 13 is positioned in a plane substantially parallel to backboard 101 . One end of the radiator 13 is perpendicularly connected to an end of the first feed portion 11 spaced from the first feed point 211 . Another end of the radiator 13 extends along a direction parallel to the first side portion 105 and towards the end portion 104 , then bends perpendicularly, and then extends along a direction parallel to the end portion 104 and towards the first side portion 105 . This forms the L-shaped structure.

The first ground portion 15 is positioned in the receiving space 103 . The first ground portion 15 can be a screw, a microstrip line, a probe, or other structures. One end of the first ground portion 15 is electrically connected to an end of the coupling portion A 1 adjacent to the second gap 110 . Another end of the first ground portion 15 is electrically connected to the first ground point 212 to be grounded.

The second feed portion 16 is positioned in the receiving space 103 . The second feed portion 16 can be a screw, a microstrip line, a probe, or other connecting structures. An end of the second feed portion 16 is electrically connected to a side of the radiating portion A 2 adjacent to the first gap 109 . In this embodiment, the radiating portion A 2 is divided into a coupling section A 21 and a radiating section A 22 .

The coupling section A 21 is formed by the portion of the side frame 102 from the second feed portion 16 to the first gap 109 . The radiating section A 22 is formed by the portion of the side frame 102 from the second feed portion 16 to the third gap 111 .

In this embodiment, the second feed portion 16 is connected to the radiating portion A 2 at a position not at a middle portion of the radiating portion A 2 . The radiating section A 22 is longer than the coupling section A 21 . Another end of the second feed portion 16 is electrically connected to the second feed point 123 to supply current to the radiating section A 22 of the radiating portion A 2 .

The second ground portion 17 is positioned in the receiving space 103 . The second ground portion 17 can be a screw, a microstrip line, a probe, or other structures. One end of the second ground portion 17 is electrically connected to an end of the radiating section A 22 adjacent to the third gap 111 . Another end of the second ground portion 17 is electrically connected to the second ground point 215 to be grounded.

When the first feed point 211 supplies current, the current flows through the first feed portion 11 and the radiator 13 , and is coupled to the coupling portion A 1 through the radiator 13 . The coupling portion A 1 further couples to the coupling section A 21 through the first gap 109 . Then each of the radiator 13 , the coupling portion A 1 , and the coupling section A 21 activate a different operating mode to generate radiation signals in a different radiation frequency band.

For example: the coupling portion A 1 can activate a first operating mode to generate radiation signals in a first radiation frequency band; the radiator 13 can activate a second operating mode to generate radiation signals in a second radiation frequency band; and the coupling section A 21 can activate a third operating mode to generate radiation signals in a third radiation frequency band.

In this embodiment, the first operating mode and the second operating mode are both Long Term Evolution Advanced (LTE-A) middle frequency operating modes. The third operating mode is a LTE-A high frequency operating mode. Frequencies of the third radiation frequency band are higher than frequencies of the second radiation frequency band. Frequencies of the second radiation frequency band are higher than frequencies of the first radiation frequency band.

In this embodiment, the first radiation frequency band is about 1710-1880 MHz. The second radiation frequency band is about 2000-2300 MHz. The third radiation frequency band is about 2496-2690 MHz. That is, a frequency spread of the first to third radiation frequency bands is about 1710-2690 MHz.

When the second feed source 213 supplies current, the current flows through the second feed portion 16 and the radiating section A 22 , and is grounded through the second ground portion 17 . Then, the second feed point 213 , the second feed portion 16 , the radiating section A 22 , and the second ground portion 17 cooperatively form an inverted-F antenna to activate a fourth operating mode to generate radiation signals in a fourth radiation frequency band.

In this embodiment, the fourth operating mode is a LTE-A low frequency operating mode. Frequencies of the first radiation frequency band are higher than frequencies of the fourth radiation frequency band. The fourth radiation frequency band is about 700-960 MHz.

In FIG. 1 and FIG. 3 , the antenna structure 100 further includes a switching circuit 18 . One end of the switching circuit 18 is electrically connected to the second ground portion 17 . Then the switching circuit 18 is electrically connected to the radiating section A 22 of the radiating portion A 2 through the second ground portion 17 . Another end of the switching circuit 18 is electrically connected to the second ground point 215 to be grounded. The switching circuit 18 is used to adjust the fourth radiation frequency band, that is, the low frequency band of the antenna structure 100 .

As illustrated in FIG. 4 , the switching circuit 18 includes a switch 181 and a plurality of switching elements 183 . The switch 181 is electrically connected to the second ground portion 17 . The switch 181 is also electrically connected to the radiating section A 22 of the radiating portion A 2 through the second ground portion 17 . Each of the switching elements 183 can be an inductor, a capacitor, or a combination of the inductor and the capacitor. The switching elements 183 are connected to each other in parallel. One end of each switching element 183 is electrically connected to the switch 181 . The other end of each switching element 183 is electrically connected to the second ground point 215 to be grounded.

Using the switch 181 , the radiating section A 22 can be switched to connect with different switching elements 183 . Since each switching element 183 has a different impedance, the low frequency band of the antenna structure 100 , that is, the fourth radiation frequency band, can be adjusted, as described in the next paragraph.

For example, the switching circuit 18 may include four switching elements 183 . The four switching elements 183 are all inductors and have respective inductance values of about 2 nH, 10 nH, 15 nH, and 27 nH. When the switch 181 is switched to connect with the switching element 183 having an inductance value of about 2 nH, the antenna structure 100 can work at a frequency band of LTE-A band8 (704-803 MHz). When the switch 181 is switched to connect with the switching element 183 having an inductance value of about 10 nH, the antenna structure 100 can work at a frequency band of LTE-A band5 (824-894 MHz). When the switch 181 is switched to connect with the switching element 183 having an inductance value of about 15 nH, the antenna structure 100 can work at a frequency band of LTE-A band20 (791-862 MHz). When the switch 181 is switched to connect with the switching element 183 having an inductance value of about 27 nH, the antenna structure 100 can work at a frequency band of LTE-A band17 (704-746 MHz). That is, through control of the switch 181 , a low frequency band of the antenna structure 100 can cover 700-960 MHz.

As illustrated in FIG. 3 , the antenna structure 100 further includes a switching unit 19 . One end of the switching unit 19 is electrically connected to the first ground portion 15 . Then the switching unit 19 is electrically connected to the coupling portion A 1 through the first ground portion 15 . Another end of the switching unit 19 is electrically connected to the first ground point 212 to be grounded. The switching unit 19 adjusts the first radiation frequency band and the second radiation frequency band, that is, the middle frequency band of the antenna structure 100 . In this embodiment, a circuit structure and a working principle of the switching unit 19 are consistent with the switching circuit 18 shown in FIG. 4 .

In FIG. 5A to FIG. 5F , the radiator 13 , the coupling portion A 1 , and the coupling section A 21 of the radiating portion A 2 are shown having other configurations. However, the three portions (i.e., the radiator 13 , the coupling portion A 1 , and the coupling section A 21 ) must always be spaced apart from each other, the radiator 13 is electrically connected to the first feed point 211 , and the coupling portion A 1 is electrically connected to the first ground point 212 to be grounded. Additionally, when the radiator 13 supplies current, the current is coupled to one of the coupling portion A 1 and the coupling section A 21 . The one of the coupling portion A 1 and the coupling section A 21 further couples the current to the other one of the coupling portion A 1 and the coupling section A 21 .

In FIG. 5A , the radiator 13 a is substantially inverted T-shaped. One end of the radiator 13 a is electrically connected to an end of the first feed portion 11 spaced away from the first feed point 211 . Another end of the radiator 13 a extends along a direction parallel to the first side portion 105 and towards the end portion 104 , then splits and bends perpendicularly, then extends along two opposite directions parallel to the end portion 104 and towards the first side portion 105 and the second side portion 106 respectively. The extension continues until the radiator 13 a passes over the first gap 109 . Thus, the radiator 13 a forms the T-shaped structure. One end of the radiator 13 a is spaced away from the coupling portion A 1 . Another end of the radiator 13 a is spaced away from the coupling section A 21 .

In FIG. 5B , the radiator 13 b is substantially a loop. One end of the radiator 13 b is electrically connected to the first feed point 211 . Another end of the radiator 13 b is grounded. Then the radiator 13 b forms a loop antenna.

In FIG. 5C , the radiator 13 c is substantially L-shaped. One end of the radiator 13 c is electrically connected to an end of the first feed portion 11 spaced away from the first feed point 211 . Another end of the radiator 13 c extends along a direction parallel to the first side portion 105 and towards the end portion 104 , then bends perpendicularly, then extends along a direction parallel to the end portion 104 and towards the second side portion 106 . Thus, the radiator 13 c forms the L-shaped structure.

In FIG. 5D , the radiator 13 d is substantially a loop. One end of the radiator 13 d is electrically connected to the first feed point 211 . Another end of the radiator 13 d is grounded. Then the radiator 13 d forms an inverted-F antenna.

In FIG. 5E , a structure of the radiator 13 e is the same as the structure of the radiator 13 . The antenna structure 100 further includes an extending section A 23 . The extending section A 23 is substantially L-shaped. One end of the extending section A 23 is electrically connected to the coupling section A 21 . Another end of the extending section A 23 extends along a direction parallel to the first side portion 105 and spaced away from the end portion 104 , then bends perpendicularly, then extends along a direction parallel to the end portion 104 and towards the first side portion 106 . The extension continues until the extending section A 23 passes over the first gap 109 and is spaced away from the radiator 13 e.

When the first feed point 211 supplies current, the current flows through the radiator 13 e , is coupled to the extending section A 23 through the radiator 13 e , and further flows through the coupling section A 21 . Then the current from the coupling section A 21 is further coupled to the coupling portion A 1 through the first gap 109 .

In FIG. 5F , a structure of the radiator 13 f is the same as the structure of the radiator 13 . The antenna structure 100 further includes an extending section A 11 . The extending section A 11 is substantially L-shaped. One end of the extending section A 11 is electrically connected to the coupling portion A 1 . Another end of the extending section A 11 extends along a direction parallel to the first side portion 105 and away from the end portion 104 , then bends perpendicularly, then extends along a direction parallel to the end portion 104 and towards the second side portion 106 . The extension continues until the extending section A 11 passes over the first gap 109 and is spaced away from the coupling section A 21 .

When the first feed point 211 supplies current, the current flows through the radiator 13 f , is coupled to the coupling portion A 1 through the radiator 13 f , and further flows through the extending section A 11 . Then the current from the extending section A 11 is further coupled to the coupling section A 21 .

As described above, the antenna structure 100 can activate the first operating mode and the second operating mode to generate radiation signals in the middle frequency band. The antenna structure 100 can further activate the third operating mode to generate radiation signals in the high frequency band and activate the fourth operating mode to generate radiation signals in the low frequency band. Then, the wireless communication device 200 can use carrier aggregation (CA) technology of LTE-A to receive or send wireless signals at multiple frequency bands simultaneously. In detail, the wireless communication device 200 can use the CA technology of LTE-A and use the radiator 13 , the coupling portion A 1 , and the radiating portion A 2 to receive or send wireless signals at multiple frequency bands simultaneously, that is, can realize 2CA or 3CA.

FIG. 6 is a scattering parameter graph of the antenna structure 100 , when the antenna structure 100 works at the low frequency operating mode. Curve S 61 is a scattering parameter of the antenna structure 100 when the switch 181 is switched to connect with a switching element 183 having an inductance value of about 2 nH. Curve S 62 is a scattering parameter of the antenna structure 100 when the switch 181 is switched to connect with a switching element 183 having an inductance value of about 10 nH. Curve S 63 is a scattering parameter of the antenna structure 100 when the switch 181 is switched to connect with a switching element 183 having an inductance value of about 15 nH. Curve S 64 is a scattering parameter of the antenna structure 100 when the switch 181 is switched to connect with a switching element 183 having an inductance value of about 27 nH.

FIG. 7 is a total radiating efficiency graph of the antenna structure 100 , when the antenna structure 100 works at the low frequency operating mode. Curve S 71 is a total radiating efficiency of the antenna structure 100 when the switch 181 is switched to connect with a switching element 183 having an inductance value of about 2 nH. Curve S 72 is a total radiating efficiency of the antenna structure 100 when the switch 181 is switched to connect with a switching element 183 having an inductance value of about 10 nH. Curve S 73 is a total radiating efficiency of the antenna structure 100 when the switch 181 is switched to connect with a switching element 183 having an inductance value of about 15 nH. Curve S 74 is a total radiating efficiency of the antenna structure 100 when the switch 181 is switched to connect with a switching element 183 having an inductance value of about 27 nH.

FIGS. 6-7 show a frequency of the antenna structure 100 at the low frequency operating mode can be effectively adjusted by the switch 181 . When different frequency bands of the low frequency band are switched in, the middle frequency band and the high frequency band of the antenna structure 100 may not be affected.

FIG. 8 is a scattering parameter graph of the antenna structure 100 , when the antenna structure 100 works at the middle and high frequency operating modes. FIG. 9 is a total radiating efficiency graph of the antenna structure 100 , when the antenna structure 100 works at the middle and high frequency operating modes.

In FIG. 6 to FIG. 9 , the antenna structure 100 may completely cover system bandwidths required by current communication systems. For example, the low frequency band of the antenna structure 100 can cover 700-960 MHz, and the antenna efficiency is greater than −6 dB. The middle and high frequency bands of the antenna structure 100 can cover 1710-2690 MHz, and the antenna efficiency is greater than −5 dB, which meets the antenna design requirements.

The antenna structure 100 includes the housing 10 . The radiator 13 , the coupling portion A 1 , and the coupling section A 21 are spaced apart from each other. Then the frequencies of the low, middle, and high frequency bands of the antenna structure 100 can be controlled through secondary coupling. The frequencies of the low, middle, and high frequency bands of the antenna structure 100 can also meet the requirements of Carrier Aggregation (CA) of Long Term Evolution Advanced (LTE-Advanced).

The embodiments shown and described above are only examples. Many details are often found in the art such as the other features of the antenna structure and the wireless communication device. Therefore, many such details are neither shown nor described. Even though numerous characteristics and advantages of the present disclosure have been set forth in the foregoing description, together with details of the structure and function of the present disclosure, the disclosure is illustrative only, and changes may be made in the details, especially in matters of shape, size, and arrangement of the parts within the principles of the present disclosure, up to and including the full extent established by the broad general meaning of the terms used in the claims. It will therefore be appreciated that the embodiments described above may be modified within the scope of the claims.