CN107293838A - Communication device with antenna element having narrow ground plane clearance area - Google Patents

Abstract

The invention provides a communication device with an antenna element with a narrow ground plane clearance area. The radiating metal sheet of the antenna element is not in the same plane as the system circuit board. The radiating metal plate and the ground plane are separated by a clearance interval. The radiation metal sheet comprises a first metal sheet, a second metal sheet and a feed-in metal sheet. The first metal sheet has a first terminal, and the first terminal is connected to the ground plane through the first inductance element. The second metal sheet has a second end point, and the second end point is connected to the ground plane through the second inductance element. A first gap is formed between the coupling metal sheet and the first metal surface. A second gap is formed between the coupling metal sheet and the second metal surface. The coupling metal sheet is connected to a signal source. The metal shell of the communication device provided by the invention only needs to be provided with the narrow metal clearance area at the frame as the antenna window of the antenna element, thereby achieving the beautiful appearance and the firmness of the communication device with the metal shell.

Description

Communication device with antenna element with narrow ground plane clearance

technical field

The present invention relates to a communication device, and more particularly to a communication device having an antenna element with a narrow ground plane clearance.

Background technique

With the rapid development of mobile communication technology, various mobile communication products continue to emerge, among which communication devices (such as smart phones and tablet computers, etc.) are the most popular. For these communication devices, thin and light appearance is a trend. Nowadays, more and more attention is paid to the design of the appearance of the communication device and the robustness of the device. Therefore, how to design a communication device with a thin and light appearance and a metal case, and an antenna element suitable for such a communication device, for example: make the antenna element have broadband or multi-frequency operation characteristics, and at the same time, the metal case only needs to be provided at its frame Narrow metal headroom (for example: the width of the metal headroom is less than 4mm or less), so that the communication device has a beautiful and thin appearance, has become an important issue to be solved.

Contents of the invention

The present invention provides a communication device with an antenna element with a narrow ground plane clearance area, including the antenna element with a narrow ground plane clearance area, so that the metal casing of the communication device only needs to set a narrow metal clearance area at its frame as the antenna element Antenna window, thereby achieving the aesthetic appearance and robustness of a communication device with a metal housing.

The communication device of the present invention includes a system circuit board and an antenna element. The system circuit board has a ground plane. The antenna element includes a radiating metal sheet. The radiating metal sheet is not on the same plane as the system circuit board. The radiating metal sheet extends along the first edge of the system circuit board, and the radiating metal sheet is separated from the ground plane by a clear space. The clear space has a width, and the ground plane is not set in the clear space. The radiating metal sheet has a first end point and a second end point, and the distance between the first end point and the second end point is the length of the radiating metal sheet. The radiation metal sheet includes a first metal sheet, a second metal sheet and a coupling metal sheet. The first metal sheet has a first terminal, and the first terminal is electrically connected to the ground plane through the first inductance element. The second metal sheet has a second terminal, and the second terminal is electrically connected to the ground plane through the second inductance element. The coupling metal sheet is located between the first metal sheet and the second metal sheet, and is located on the same plane as the first metal sheet and the second metal sheet. There is a first gap between the coupling metal sheet and the first metal sheet, there is a second gap between the coupling metal sheet and the second metal sheet, and the coupling metal sheet has an antenna feeding point. The antenna feeding point is electrically connected to a signal source on the system circuit board via a feeding wire. The distance between the first gap and the antenna feeding point is not greater than the width of the clearance zone, and the distance between the second gap and the antenna feeding point is also not greater than the width of the clearance zone.

In an embodiment of the present invention, the above-mentioned feeding metal wire, coupling metal sheet, first gap, first metal sheet, and first inductance element form a first closed path, and the first closed path generates the first closed path located in the antenna element. A frequency band of the first resonant mode.

In an embodiment of the present invention, the above-mentioned feeding metal wire, coupling metal sheet, second gap, second metal sheet, and second inductance element form a second closed path, and the second closed path generates a second closed path located at the antenna element. The second resonant mode of the second frequency band.

In an embodiment of the present invention, the above-mentioned radiating metal sheet of the antenna element extends along a first edge of the system circuit board, wherein the first edge may be a short edge of the communication device.

In an embodiment of the present invention, the feed-in metal wire of the above-mentioned antenna element is located in the clearance area, and the feed-in metal wire can be in a straight line shape, a step shape, a multi-bend shape, or have a third inductance element. The first inductance element, the second inductance element and the third inductance element of the antenna element can all be a chip inductance element or a distributed inductance element. The feeding wire of the antenna element can be further electrically connected to the signal source via a matching circuit.

In order to make the above-mentioned features and advantages of the present invention more comprehensible, the following specific embodiments are described in detail with reference to the accompanying drawings.

Description of drawings

FIG. 1 is a structural diagram of the first embodiment of the communication device of the present invention;

FIG. 2 is a structural diagram of a second embodiment of the communication device of the present invention;

3 is a return loss diagram for illustrating an antenna element of a second embodiment of the present invention;

4 is an antenna efficiency diagram for illustrating an antenna element of a second embodiment of the present invention;

FIG. 5 is a structural diagram of a third embodiment of the communication device of the present invention;

6 is a structural diagram of other embodiments of the first inductance element and the second inductance element of the present invention;

FIG. 7 is another return loss diagram for illustrating the antenna element of the second embodiment of the present invention.

Reference signs:

10, 20, 50: communication device

101: Border

11: System circuit board

111: ground plane

112: First Edge

12: Radiant metal sheet

121: first endpoint

122: second endpoint

123: First metal sheet

124: Second metal sheet

125: Coupling metal sheet

126: First Gap

127: Second Gap

128: Antenna feed point

131, 531: the first inductance element

132, 532: the second inductance element

133, 533: the third inductance element

14: Clearance interval

15, 25: Feed-in metal wire

161, 261, 561: the first closed path

162, 262, 562: second closed path

17: Signal source

18: Matching circuit

301: First resonance mode

302: Second resonance mode

31: First (high frequency) frequency band

32: Second (low frequency) band

41: Antenna efficiency curve for the first frequency band

42: Antenna efficiency curve for the second frequency band

61: Adjustable inductance element

62: Switchable inductive element group

621～624: switch

625～628: inductance

T61, T62: connection end

701, 702: Frequency variation of the second resonance mode when using a switchable inductive element set

t: width

detailed description

FIG. 1 is a structural diagram of the first embodiment of the communication device of the present invention. As shown in FIG. 1 , the communication device 10 may be, for example, a smart phone or a tablet computer with a metal casing, and the communication device 10 includes a system circuit board 11 . The system circuit board 11 has a ground plane 111 and an antenna element. The antenna element includes a radiating metal sheet 12 , and the radiating metal sheet 12 is not on the same plane as the system circuit board 11 . The radiating metal sheet 12 extends along the first edge 112 of the system circuit board 11 . The radiating metal sheet 12 and the ground plane 111 are separated by a clear space 14 , and the ground plane 111 is not disposed in the clear space 14 . In other words, the ground plane 111 and the clearance space 14 are disposed on a surface of the system circuit board 11 , and the clearance space 14 is located between the radiation metal sheet 12 and the ground plane 111 .

The radiating metal sheet 12 has a first terminal 121 and a second terminal 122 . The distance between the first end point 121 and the second end point 122 is the length of the radiating metal sheet 12 . The radiation metal sheet 12 includes a first metal sheet 123 , a second metal sheet 124 and a coupling metal sheet 125 . The first metal sheet 123 has a first terminal 121 , and the first terminal 121 is electrically connected to the ground plane 111 through the first inductance element 131 . The second metal sheet 124 has a second terminal 122 , and the second terminal 122 is electrically connected to the ground plane 111 through the second inductance element 132 .

The coupling metal piece 125 is disposed between the first metal piece 123 and the second metal piece 124 , and the coupling metal piece 125 , the first metal piece 123 and the second metal piece 124 are located on the same plane. There is a first gap 126 between the coupling metal piece 125 and the first metal piece 123 . There is a second gap 127 between the coupling metal piece 125 and the second metal piece 124 . The coupling metal sheet 125 has an antenna feeding point 128 . The antenna feed point 128 is electrically connected to the signal source 17 on the system circuit board 11 via the feed wire 15 , and the signal source 17 may be, for example, a transceiver (not shown) in the communication device 10 .

The communication device 10 also includes a frame 101 . Wherein, the frame 101 surrounds the system circuit board 11 , and for the convenience of illustration, FIG. 1 only shows part of the frame 101 . In one embodiment, the frame 101 may be made of non-conductive material. In other words, the communication device 10 further includes the non-metal frame 101 , and the first metal sheet 123 , the second metal sheet 124 and the coupling metal sheet 125 can be disposed on a surface of the non-metal frame 101 , for example. In another embodiment, the frame 101 may also be made of conductive material. For example, part of the frame 101 can be formed by the first metal sheet 123 , the second metal sheet 124 and the coupling metal sheet 125 .

In operation, the feeding metal line 15 , the coupling metal piece 125 , the first gap 126 , the first metal piece 123 and the first inductance element 131 can form a first closed path 161 . In addition, the antenna element can generate a first resonance mode through the first closed path 161, and the first resonance mode is located in a first frequency band (eg, a high frequency band) of the antenna element. Specifically, the feed-in signal from the signal source 17 can be transmitted to the coupling metal sheet 125 through the feed-in wire 15 . In addition, the feed signal can be capacitively coupled from the coupling metal piece 125 to the first metal piece 123 through the first gap 126 . In other words, by coupling the metal sheet 125 and the first gap 126, the first closed path 161 can form a capacitively coupled and fed loop resonant path, thereby causing the length of the first closed path 161 to be shorter than the first frequency band (for example, 1/4 wavelength of the lowest frequency of the high frequency band). In addition, the first inductance element 131 can be used to increase the equivalent resonance length of the first closed path 161 .

In other words, the first inductance element 131 and the coupling feed formed by the first gap 126 can greatly reduce the physical length of the first closed path 161 , thereby helping to reduce the size of the antenna element. For example, the length of the first metal sheet 123 may be, for example, 0.1 times the wavelength of the lowest frequency of the first frequency band (eg, high frequency band). Moreover, the capacitive reactance of the parasitic capacitance between the coupling metal piece 125 and the first metal piece 123 can also compensate the inductive reactance of the first inductive element 131 . Thereby, the impedance matching of the first resonant mode of the antenna element will be smoother, or the first resonant mode has a double resonance characteristic, thereby helping to increase the first frequency band (for example, high frequency) of the antenna element. frequency band) bandwidth.

On the other hand, the feeding metal line 15 , the coupling metal piece 125 , the second gap 127 , the second metal piece 124 and the second inductance element 132 can form a second closed path 162 . In addition, the antenna element can generate a second resonant mode through the second closed path 162, and the second resonant mode is located in a second frequency band (eg, a low frequency band) of the antenna element. Specifically, the feed-in signal from the signal source 17 can be transmitted to the coupling metal sheet 125 through the feed-in wire 15 . In addition, the feed signal can be capacitively coupled from the coupling metal piece 125 to the second metal piece 124 through the second gap 127 . In other words, the second closed path 162 may form another loop resonance path fed by capacitive coupling, thereby causing the length of the second closed path 162 to be less than 1/4 wavelength of the lowest frequency of the second frequency band (eg, low frequency band) . In addition, the second inductance element 132 can be used to increase the equivalent resonance length of the second closed path 162 .

In other words, the second inductance element 132 and the coupling feed formed by the second gap 127 can greatly reduce the physical length of the second closed path 162 , thereby helping to reduce the size of the antenna element. For example, the length of the second metal sheet 124 may be, for example, 0.13 times the wavelength of the lowest frequency of the second frequency band (eg, low frequency band). Moreover, the capacitive reactance of the parasitic capacitance between the coupling metal piece 125 and the second metal piece 124 can also compensate the inductive reactance of the second inductive element 132 . Thereby, the impedance matching of the second resonant mode of the antenna element will be smoother, or the second resonant mode has the characteristics of double resonance, thereby helping to increase the second frequency band (for example, low frequency band) of the antenna element. ) bandwidth.

In general, the antenna element corresponds to a coupled excitation loop antenna (loop antenna), and the loop antenna includes a dual loop resonant path to operate in a first frequency band (eg, high frequency band) and a second frequency band (eg, , low frequency band). In addition, in the overall configuration, the clearance space 14 has a width t, and the width t is between 0.5 mm and 4 mm. In other words, the communication device 10 has a narrow headroom 14 adjacent to the frame 101 (ie, a narrow ground clearance), so that the metal housing of the communication device 10 can have a narrow metal headroom to serve as an antenna window for the antenna element. Wherein, the width t of the clearance space 14 is at least 0.5 mm, so as to separate the radiating metal sheet 12 and the ground plane 111 . In addition, the width t of the headroom section 14 is at most 4.0 mm, so as to maintain the overall appearance of the communication device 10 beautifully.

It is worth mentioning that the coupling metal sheet 125 is mainly used to electrically connect the antenna feeding point 128 and the feeding metal wire 15 . Therefore, the length of the coupling metal piece 125 only accounts for a small part of the overall length of the antenna element. Relatively, the distance between the first gap 126 and the antenna feeding point 128 is not greater than the width of the clearance zone 14 , and the distance between the second gap 127 and the antenna feeding point 128 is not greater than the width of the clearance zone 14 .

In addition, since the coupled feed-in, the first inductive element 131 and the second inductive element 132 can greatly reduce the size of the radiating metal sheet 12, the radiating metal sheet 12 can be arranged on the short side of the communication device 10 (for example: a smart phone) frame without occupying the long frame of the communication device 10 . In other words, the first edge 112 of the communication device 10 may be a short edge of the communication device 10 . Furthermore, the terminal 121 and the terminal 122 of the radiating metal sheet 12 are respectively electrically connected to the ground plane 111 through an inductance element. In other words, at the corners adjacent to the two ends of the first edge 112 , the radiating metal sheet 12 does not form an open end. In this way, the effect on the performance of the antenna element caused by the user holding the communication device 10 can be greatly reduced.

Furthermore, the feeding metal wire 15 of the antenna element is located in the clearance area 14 , and the feeding metal wire 15 can be a straight line or have a third inductance element 133 . The feeding metal line 15 can be further electrically connected to the signal source 17 via a matching circuit 18 . Wherein, the matching circuit 18 can improve the impedance matching of the antenna element in the first frequency band and the second frequency band, and further increase the operating bandwidth of the antenna element. In addition, the first inductance element 131 , the second inductance element 132 and the third inductance element 133 can all be a chip inductance element or a distributed inductance element.

FIG. 2 is a structural diagram of a second embodiment of the communication device of the present invention. The main difference from the embodiment in FIG. 1 is that the feeding metal wire 25 in the communication device 20 of FIG. The incoming wire 25 increases its length within the narrow headroom 14. As the length of the feeding metal wire 25 increases, the equivalent resonance lengths of the first closed path 261 and the second closed path 262 can be increased, so that the corresponding frequencies of the first resonance mode and the second resonance mode reduce. In this way, the purpose of reducing the size of the antenna element can be achieved, and the design flexibility can also be increased. As for the detailed structure of other components in the embodiment of FIG. 2, which is the same or similar to that of the embodiment in FIG. 1, and under this similar structure, the communication device 20 listed in the second embodiment of FIG. Examples behave similarly.

FIG. 3 is a diagram illustrating return loss of an antenna element according to a second embodiment of the present invention. In the second embodiment, the length of the system circuit board 11 may be 133 mm, and the width of the system circuit board 11 may be 70 mm. The length of the ground plane 111 may be 130 mm, and the width of the ground plane 111 is 70 mm. The length of the first metal piece 123 may be 16.5 mm, the length of the second metal piece 124 may be 48.5 mm, and the size of the coupling metal piece 125 may be 3×6 mm ² . The first inductance element 131 can use a 1.5nH chip inductance element, and the second inductance element 132 can use a 2.4nH chip inductance element. In this configuration, the width t of the clearance zone 14 is only 3 mm.

As shown in FIG. 3 , the resonance mode 301 is the first resonance mode generated by the first closed path 261 , and the resonance mode 301 is located within the first frequency band 31 . In addition, the resonance mode 302 is a second resonance mode generated by the second closed path 262 , and the resonance mode 302 is located within the second frequency band 32 . Furthermore, the first frequency band 31 may cover about 1710-2690 MHz, that is, it may cover related operating frequency bands of LTE and WWAN. The second frequency band 32 may cover approximately 824-960 MHz, that is, may cover GSM850, GSM900 and LTE band5/band8 frequency bands.

FIG. 4 is a diagram illustrating antenna efficiency of an antenna element according to a second embodiment of the present invention. As shown in FIG. 4 , the antenna efficiency curve 41 is 62%-88% in the first frequency band 31 , and the antenna efficiency curve 42 is 40%-59% in the second frequency band 32 . In other words, the antenna element is suitable for practical mobile communication devices.

FIG. 5 is a structural diagram of a third embodiment of the communication device of the present invention. The main difference from FIG. 1 is that the first inductance element 531, the second inductance element 532 and the third inductance element 533 in the communication device 50 of FIG. 5 all use a distributed inductance element, and the distributed inductance element can be formed by a Made of curved metal wires. In this way, the equivalent resonance lengths of the first closed path 561 and the second closed path 562 can be increased, thereby achieving the purpose of reducing the size of the antenna element and increasing the design flexibility. As for the detailed structure of other components in the embodiment of FIG. 2, which is the same or similar to that of the embodiment in FIG. 1, and under this similar structure, the communication device 50 listed in the third embodiment of FIG. Examples behave similarly.

FIG. 6 is a structural diagram of other embodiments of the first inductance element and the second inductance element of the present invention. As shown in FIG. 6 , both the first inductive element 131 and the second inductive element 132 can be an adjustable inductive element 61 or an inductive element group 62 . Wherein, the inductance element group 62 includes a plurality of switches 621 - 624 and a plurality of inductors 625 - 628 . In addition, the switches 621 - 624 correspond one-to-one to the inductors 625 - 628 , and each switch and the corresponding inductor are connected in series between the connection terminals T61 and T62 . In one embodiment, the communication device can change the inductance values of the first inductive element 131 and the second inductive element 132 through an adjustable circuit or a switchable circuit. For example, the adjustable circuit or the switching circuit can use the control signal to directly control the adjustable inductive element 61 , or use the control signal to control the conduction number of the switches 621 - 624 in the inductive element group 62 . Thereby, the equivalent resonance lengths of the first closed path and the second closed path will change correspondingly, thereby changing the frequency of the first resonance mode and the second resonance mode, so that the first frequency band 31 or the second frequency band of the antenna element Frequency band 32 may cover different frequency ranges.

FIG. 7 is another return loss diagram for illustrating the antenna element of the second embodiment of the present invention, wherein the second inductance element 132 is formed by a switchable inductance element group 62 . Specifically, the switching circuit can change the conducting number of the switches 621 - 624 , and then can adjust the inductance value of the second inductance element 132 . Thereby, the resonant length of the second closed path can be changed, thereby changing the frequency of the second resonant mode. For example, when the inductance of the second inductance element 132 is adjusted to 5.6 nH, the antenna element can generate a resonant mode 701 through the second closed path, and the resonant mode 701 can cover about 746-787 MHz. When the inductance of the second inductance element 132 is adjusted to 8.2 nH, the antenna element can generate a resonant mode 702 through the second closed path, and the resonant mode 702 can cover about 698-746 MHz. In this way, the antenna element can cover more LTE operating frequency bands (eg, LTE band12/band13 frequency bands).

In other words, through the control of the adjustable circuit or the switchable circuit, the position of the second frequency band of the antenna element can be adjusted, so that the antenna element can cover a wider operating bandwidth. For example, the second frequency band of the antenna element may cover about 824-960 MHz when passive inductive elements are used. With the control of the adjustable circuit or the switchable circuit, the second frequency band of the antenna element can cover about 700-824 MHz. Thereby, the frequency range of the second frequency band of the antenna element can cover about 698-960 MHz. At the same time, the first frequency band of the antenna element can still cover 1710-2690 MHz. That is, in an embodiment, the antenna element may cover the 824-960 MHz/1710-2690 MHz frequency band or the 698-960 MHz/1710-2690 MHz frequency band under the LTE/WWAN communication standard.

To sum up, the coupling-feed structure of the antenna element and the inductive short-circuit structure of the two terminals of the antenna element of the present invention can greatly reduce the size of the radiating metal sheet, so that the radiating metal sheet can be placed adjacent to the communication device. on the short edge of the border. In addition, the communication device has a narrow headroom (ie, a narrow ground plane headroom) adjacent to the bezel. In this way, the metal shell of the communication device only needs to provide a narrow metal clearance area adjacent to the frame to serve as an antenna window, thereby maintaining the overall appearance and firmness of the communication device.

Although the present invention has been disclosed above with the embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, this The scope of protection of the invention should be determined by the appended claims.

Claims (11)

1. A communication device, characterized in that the communication device comprises a system circuit board and an antenna element, the system circuit board has a ground plane, the antenna element comprises a radiating metal sheet, and the radiating metal sheet Not on the same plane as the system circuit board, the radiating metal sheet extends along a first edge of the system circuit board, the radiating metal sheet is separated from the ground plane by a clear space, and the clear space has a width, the ground plane is not set in the clearance zone, the radiating metal sheet has a first end point and a second end point, the distance between the first end point and the second end point is The length of the radiating metal sheet, the radiating metal sheet includes: a first metal sheet, having the first end point, the first end point is electrically connected to the ground plane through a first inductance element; a second metal sheet, having the second terminal, the second terminal is electrically connected to the ground plane via a second inductance element; and A coupling metal sheet, between the first metal sheet and the second metal sheet, and on the same plane as the first metal sheet and the second metal sheet, the coupling metal sheet and the first metal sheet There is a first gap between the sheets, there is a second gap between the coupling metal sheet and the second metal sheet, and the coupling metal sheet has an antenna feed point, and the antenna feed point passes through a feed The incoming metal line is electrically connected to a signal source located on the system circuit board, wherein the distance between the first gap and the antenna feeding point is not greater than the width of the clearance interval, and the second gap and the The distance between the antenna feeding points is also not greater than the width of the clearance interval. 2 . The communication device according to claim 1 , wherein the first metal sheet, the second metal sheet and the coupling metal sheet are formed on a surface of a frame of the communication device. 3. The communication device according to claim 1, wherein the feeding metal wire, the coupling metal sheet, the first gap, the first metal sheet and the first inductance element form a A first closed path that generates a first resonant mode in a first frequency band of the antenna element. 4. The communication device according to claim 1, wherein the feeding metal wire, the coupling metal sheet, the second gap, the second metal sheet and the second inductance element form a A second closed path that generates a second resonant mode in a second frequency band of the antenna element. 5. The communication device according to claim 1, wherein the first edge is a short edge of the communication device. 6 . The communication device according to claim 1 , wherein the width of the clearance zone is between 0.5 mm and 4.0 mm. 7. The communication device according to claim 1, wherein the feeding metal wire is located in the clear space, and the feeding metal wire can be in a straight line shape or a step shape or a multi-step shape The secondary curved shape may have a third inductance element. 8. The communication device according to claim 7, wherein the step-shaped feeding metal wire extends toward the second metal sheet, and the length of the second metal sheet is longer than that of the first metal sheet length. 9. The communication device according to claim 1, wherein the feeding metal line is further electrically coupled and connected to the signal source via a matching circuit. 10. The communication device according to claim 1 or 7, wherein the first inductance element, the second inductance element and the third inductance element are all a chip inductance element or a distributed inductance element element. 11. The communication device according to claim 1, wherein the second inductive element can be an adjustable inductive element or an inductive element group, and the communication device is configured via an adjustable circuit or a switchable A circuit changes the inductance value of the second inductance element, so that the second frequency band of the antenna element covers different frequency ranges.