WO2016138650A1

WO2016138650A1 - Multiple input multiple output wireless antenna structures and communication device

Info

Publication number: WO2016138650A1
Application number: PCT/CN2015/073657
Authority: WO
Inventors: Nga Guy JOSEPH
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2015-03-04
Filing date: 2015-03-04
Publication date: 2016-09-09
Anticipated expiration: 2017-09-04

Abstract

The present invention discloses multiple input multiple output wireless antenna structures and a circuit board. The structure include a plurality of antennas, collocated at a corner of the circuit board and configured to produce radiation patterns with different main beam directions to realize a synthetic full coverage pattern, and the plurality of antennas are coupled to a plurality of feed ports of the circuit board, respectively, and coupled to the circuit board ground. The invention therefore discloses antenna solutions to improve multiple input multiple out wireless coverage with design simplicity and lower implementation costs.

Description

MULTIPLE INPUT MULTIPLE OUTPUT WIRELESS ANTENNA STRUCTURES AND COMMUNICATION DEVICE

Field of Invention

The present invention relates to the field of wireless communication device antennas, and particularly to multiple input multiple output wireless antenna structures and communication device.

Background of the Invention

Today’s wireless communication systems are largely implementing multiple antennas to enhance data rate, system capacity and overall communication link quality. In communication devices such as wireless network access points and wireless routers implementing multiple input multiple output (MIMO) techniques, the configuration of antennas is expected to yield not only the desired diversity gain but also effective spatial coverage. A wireless access network may require a communication device to radiate in full 360-degree horizontal plane with adequate signal transmission. Moreover, in order to minimize production costs, the antennas are ideally mounted on the same circuit board with the other components of the communication device

In existing technology, when the antennas are placed on the circuit board, one way to achieve full space wireless coverage is to compose pattern synthesis from individual antenna element patterns, with the antennas placed, for example at periphery locations around the circuit board. In such configuration, antenna elements are ideally chosen to have similar radiation patterns at the intended operation frequency band. However, this method has the limitation that it may require excessively long microstrip lines which degrade signal quality or alternatively require expensive coax cables to route signals from/to the antennas. Furthermore when the antennas employed are dipole type radiators, these consume much space and may usually need special feed structures such as baluns (balanced to unbalanced transmission line conversion) to function properly. All these inconveniences indeed increase design costs and design complexity.

For these reasons, there remains a need for multiple input multiple output wireless coverage antennas with effective coverage, reduced complexity and affordable implementation costs for wireless communication devices.

Summary of the Invention

Embodiments of the present invention provide multiple input multiple output wireless antenna structures and a communication device, which can reduce cost of the circuit board and improve signal quality of the antennas.

In a first aspect, the invention discloses there is provided multiple input multiple output wireless antenna structures, including: a plurality of antennas, collocated at a corner of a substrate of a circuit board and configured to produce complementary radiation patterns with different main beam directions to realize a synthetic full coverage pattern, wherein the plurality of antennas includes at least three antennas which are coupled to a plurality of feed ports of the circuit board, respectively and coupled to a ground layer of the circuit board.

In a first possible implementation form of the multiple input multiple output wireless antenna structures according to the first aspect, the plurality of antennas comprises: a first antenna, located on a first substrate edge of the circuit board and configured to produce a first radiation pattern with a first main beam direction which is perpendicular to the first substrate edge； a second antenna, located on a second substrate edge of the circuit board and configured to produce a second radiation pattern with a second main beam direction which is perpendicular to the second substrate edge； a third antenna, configured to produce a third radiation pattern with a third main beam direction.

In a second possible implementation form of the multiple input multiple output wireless antenna structures according to the first possible implementation form, the third antenna is located on the second substrate edge of the circuit board and the third main beam direction is parallel to the second substrate edge and opposite to the first main beam direction； or, the third antenna is located on the first substrate edge of the circuit board and the third main beam direction is opposite to the second main beam direction.

In a third possible implementation form of the multiple input multiple output wireless antenna structures according to the second possible implementation form, the plurality of antennas further comprises: a fourth antenna, located on the first substrate edge of the circuit board and configured to produce a fourth radiation pattern with a fourth main beam direction opposite to the second main beam direction.

In a fourth possible implementation form of the multiple input multiple output wireless antenna structures according to the third possible implementation form, the third antenna has at least one tapered edge which is along the second substrate edge, and the fourth antenna has at least one tapered edge which is along the first substrate edge.

In a fifth possible implementation form of the multiple input multiple output wireless antenna structures according to the fourth possible implementation form, the third antenna has a first tapered edge, a second tapered edge, a third edge and a fourth edge, wherein the third edge has a trapezium bulge, the fourth edge has a groove, a bottom of the groove has a rectangle bulge, each side wall of the groove has a L shape groove, the top center of the trapezium bulge is connected to the ground layer and the top center of the rectangle bulge is connected to a third feed port, and the fourth edge is perpendicular to the first main beam direction.

In a sixth possible implementation form of the multiple input multiple output wireless antenna structures according to the fourth possible implementation form, the third antenna has a first edge, a second tapered edge, a third edge and a fourth edge, wherein the first edge runs parallel to the second substrate edge, the third edge is perpendicular to the second substrate edge, the fourth edge has a groove, a first connection point of the fourth edge and the third edge is connected to the ground layer and a second connection point of the fourth edge and the second tapered edge is connected to a third feed port.

In a seventh possible implementation form of the multiple input multiple output wireless antenna structures according to any of the above possible implementation forms, the third antenna has an elevation angle in respect to a ground layer of the circuit board.

In a eighth possible implementation form of the multiple input multiple output wireless antenna structures according to the first possible implementation form, the third antenna is located between the first substrate edge and the second substrate edge, and the third main beam direction has direction components opposite to the first main beam direction and the second main beam direction.

In a ninth possible implementation form of the multiple input multiple output wireless antenna structures according to the first or eighth possible implementation form, the third antenna has a tapered edge.

In a tenth possible implementation form of the multiple input multiple output wireless antenna structures according to the ninth possible implementation form, the third antenna has a first tapered edge, a second tapered edge, a third edge and a fourth edge, wherein the third edge has a trapezium bulge, the fourth edge has a groove, a bottom of the groove has a rectangle bulge, each side wall of the groove has a L shape groove, the top center of the trapezium bulge is connected to the ground layer and the top center of the rectangle bulge is connected to a third feed port, and the fourth edge is perpendicular to the first main beam direction.

In a eleventh possible implementation form of the multiple input multiple output wireless antenna structures according to the ninth possible implementation form, the third antenna has a first edge, a second tapered edge, a third edge and a fourth edge, wherein the first edge runs parallel to the second substrate edge, the third edge is perpendicular to the second substrate edge, the fourth edge has a groove, a first connection point of the fourth edge and the third edge is connected to the ground layer and a second connection point of the fourth edge and the second tapered edge is connected to a third feed port.

In a twelfth possible implementation form of the multiple input multiple output wireless antenna structures according to any of the above possible implementation forms, each of the plurality of antennas has load blocks, located between the substrate and the antenna, and configured to support the antenna, wherein the load blocks are conductive so that the antenna is designed in reduced size.

In a thirteenth possible implementation form of the multiple input multiple output wireless antenna structures according to any of the above possible implementation forms, the third antenna has an elevation angle in respect to a ground layer of the circuit board.

In a fourteenth possible implementation form of the multiple input multiple output wireless antenna structures according to any of the above possible implementation forms, each of the first antenna and the second antenna is of planar loop type.

In a fifteenth possible implementation form of the multiple input multiple output wireless antenna structures according to any of the above possible implementation forms, the plurality of antennas comprises dual polarization antennas to realize a dual-polarization pattern coverage.

In a second aspect, there is provided a communication device including a circuit board, comprising: a substrate； a plurality of feed ports, arranged in the substrate； a ground, arranged on the substrate； multiple input multiple output wireless antenna structures according the first aspect, coupled to the plurality of feed ports, respectively and coupled to a ground of the circuit board.

In a first possible implementation form of the communication device according to the second aspect, the circuit board further comprises a radio frequency module, coupled to the plurality of antennas, and configured to modulate and demodulate a radio signal received by the plurality of antennas, wherein the plurality of antennas are coupled to the radio frequency module through micro transmission lines.

According to embodiments of the present invention, a plurality of antennas are collocated at a corner of a circuit board and configured to produce radiation patterns with different main beam directions to realize a synthetic full coverage pattern. Since the plurality of antennas may be closely arranged at a corner of the circuit board, it is not required to employ coax cables or excessively long microstrip lines to connect the antennas to a radio frequency module, thus reducing cost of the circuit board and improving signal quality of the antennas.

Brief Description of the Drawings

To illustrate the technical solutions in the embodiments of the present invention more clearly, a brief introduction on the accompanying drawings which are needed in the description of the embodiments or the prior art is given below. Apparently, the accompanying drawings in the description below are merely some of the embodiments of the present invention, based on which other drawings can be acquired by the persons of ordinary skill in the art without any inventive effort.

FIG. 1 illustrates a schematic diagram of antenna structures at a corner of a circuit board according to an embodiment of the present invention.

FIG. 2 illustrates a schematic diagram of antenna structures according to an embodiment of the present invention.

FIG. 3 illustrates a schematic diagram of antenna structures according to another embodiment of the present invention.

FIG. 4 illustrates a schematic diagram of antenna structures at a corner of a circuit board according to another embodiment of the present invention.

FIG. 5 illustrates a schematic diagram of a circuit board according to an embodiment of the present invention.

FIG. 6 illustrates a schematic diagram of a circuit board according to another embodiment of the present invention.

FIG. 7 illustrates a schematic diagram of antenna structures at a corner of a circuit board according to another embodiment of the present invention.

FIG. 8 illustrates a schematic diagram of a circuit board according to another embodiment of the present invention.

FIG. 9 illustrates a vertical view of the second antenna in FIG. 2.

FIG. 10 illustrates a side view of the second antenna in FIG. 9.

FIG. 11 illustrates a vertical view of the third antenna in FIG. 5.

FIG. 12 illustrates a schematic diagram of structures of an antenna according to another embodiment of the present invention.

FIG. 13 illustrates a vertical view of the third antenna in FIG. 3.

FIG. 14 illustrates a side view of the third antenna in FIG. 3.

FIG. 15 illustrates a schematic diagram of a circuit board according to another embodiment of the present invention.

Embodiments of the Invention

The technical solutions in the embodiments of the present invention will be described clearly and completely hereinafter with reference to the accompanying drawings in the embodiments of the present invention. Evidently, the described embodiments are merely part, but not all, of the embodiments of the present invention. All other embodiments, which can be derived by persons of ordinary skills in the art based on the embodiments of the present invention without any inventive efforts, shall fall into the protection scope of the present invention.

In order to achieve full coverage, the antennas, for example, small size radiators, may be positioned at a restricted portion of a circuit board, for example, one corner of the board. In this configuration, antennas are chosen to have complementary radiation patterns, and full coverage pattern synthesis is realized by combining individual radiation patterns contributed by the respective antenna elements. However, the performance of the wireless coverage obtained in this solution has been limited. One limiting factor is that collocated antennas impedance matching, port-to-port isolation and radiation patterns are difficult to control since besides individual antenna form factor, antenna position and the size of the supporting ground plane all affect the overall synthesized pattern. Yet another major limitation is that closely spaced low profile antennas tend to produce similar radiation patterns according to their orientation in respect to the circuit board ground plane edge. Therefore, undesired blind angles and too low gain subsists in the synthesized pattern and so compromise full space wireless coverage.

Embodiments of the present invention introduce new antenna structures, configurations and operation mechanisms to improve multiple input multiple output wireless coverage performance with antennas collocated on a circuit board of a communication device.

FIG. 1 illustrates a schematic diagram of antenna structures at a corner of a circuit board 100 according to an embodiment of the present invention. For example, the antenna structures are multiple input multiple output wireless antenna structures.

Referring to FIG. 1, the antenna structures including a plurality of antennas are collocated at a corner of a circuit board 100, and various communication circuit modules are mounted on a substrate 110 of the circuit board 100. For example, the communication circuit modules may include MIMO Processor Module 140, Radio Frequency Module 150, Data Input/Output Module 160 and Power Source Module 170. Radio Frequency Module 150 may be mounted around a corner at which the plurality of antennas is located so that the plurality of antennas may be connected to the Radio Frequency Module 150 through microstrip transmission lines.

Referring to FIG. 1, the first main beam direction of the first antenna is –X direction, the second main beam direction is +X direction, and the third main beam direction is +Y direction. Since the antennas are collocated at one corner of the circuit board, the Radio Frequency Module 150 may be placed close to the antennas. In this scenario, only short microstrip transmission lines are needed to connect the Radio Frequency Module 150 to the antennas, thus maintaining excellent signal transmission at lower costs by avoiding the use of expensive coax cables and signal degrading long microstrip lines.

FIG. 2 illustrates a schematic diagram of antenna structures 120 according to an embodiment of the present invention. The antenna structures 120 include a plurality of antennas collocated at a corner of a circuit board 100 in a communication device.

According to embodiments of the present invention, at least three antennas are collocated at one corner of the circuit board 100. Referring to FIG. 2, the antenna structures 120 including three antennas collocated at one corner of the circuit board 100 are taken as an example, and the embodiments of the present invention are not limited thereto. For example, there may be four or more antennas collocated at one corner of the circuit board 100.

Referring to FIG. 2, the circuit board 100 may include a substrate 110, a plurality of

feed ports

111, 112 and 113, the antenna structures 120 including a plurality of

antennas

121, 122 and 123, and a ground 114. The plurality of

antennas

121, 122 and 123 are collocated at a corner of the substrate 110 of the circuit 100 and configured to produce complementary radiation patterns with different main beam (main lobe) directions to realize a synthetic full coverage pattern, and the plurality of

antennas

121, 122 and 123 are coupled to the plurality of

feed ports

111, 112 and 113 of the circuit board 100, respectively, and coupled to the ground 114, for example, at least one ground layer.

According to embodiments of the present invention, these structures include a plurality of antennas, collocated at a corner of a substrate. The plurality of antennas is coupled to a plurality of feed ports and coupled to the circuit board ground, and configured to produce complementary radiation patterns with different main beam directions. Full space coverage is then realized by pattern synthesis of the complementary elemental patterns.

According to embodiments of the present invention, a plurality of antennas are collocated at a corner of a circuit board and configured to produce complementary radiation patterns with different main beam directions to realize a synthetic full coverage pattern. Since the plurality of antennas may be closely arranged at a corner of the circuit board, it is not required to employ coax cables or excessively long microstrip lines to connect the antennas to a radio frequency module, thus reducing cost of the circuit board and improving signal quality of the antennas.

The antennas may be made from conductive material, for example, copper and stainless steel, or the like.

The geometry of the antennas may be designed to operate at the intended frequency band. Those skilled in the art may realize that the geometry of the antennas may be modified such that the antennas operate at different frequencies, and this kind of modification shall not go beyond the scope of the present invention..

The distance between the antennas may be greater than or equal to 1/2λ, wherein λ is the wavelength of radio signals transmitted by the antennas. The distance between radiators of the antennas and the circuit board may be greater than or equal to 1/20λ.

In the illustrative embodiments of the present invention, the antenna structures are metallic plate radiators mounted on the circuit board. Depending on specific design requirements, the antennas may also be printed directly on the substrate of the circuit board with further reduction in size.

According to embodiments of the present invention, the plurality of antennas may be designed as dual polarization antennas to realize a dual-polarization pattern coverage.

Specifically, when the antennas employed are dipole type radiators, the antenna structures make baluns use unnecessary because the desired impedance matching and the radiation pattern characteristics are well achieved without them. According to simulation result, antennas which may be balance type of radiators produce quite balanced directional patterns without baluns.

The circuit board on which the antennas are mounted may comprise one or more ground layers. In some embodiments, the circuit board may comprise a top layer ground and a bottom layer ground. Additional ground layers may be sandwiched in between while preserving the antenna coupling mechanisms within the scope of the present invention.

According to an embodiment of the present invention, the plurality of antennas comprises: a first antenna 121, a second antenna 122 and a third antenna 123. The first antenna antennas 121 is located on a first substrate edge 101 of the circuit board 100 and configured to produce a first radiation pattern with a first main beam direction which is perpendicular to the first substrate edge 101. The second antenna 122 is located on a second substrate edge 102 of the circuit board 100 and configured to produce a second radiation pattern with a second main beam direction which is perpendicular to the second substrate edge 102. The third antenna 123 is configured to produce a third radiation pattern with a third main beam direction.

According to embodiments of the present invention, each of the first and second antennas may be of a planar loop type so as to realize directional radiation pattern with main beam in perpendicular to substrate edge, and the embodiments of the present invention are not limited thereto, the first antenna and the second antenna may be other type of antenna which can realize directional radiation pattern with main beam in perpendicular to substrate edge. For example, each of the first and second antennas may be a full wave balanced loop radiator. The third antenna may be of a type different from the planar loop type.

According to embodiments of the present invention, the third antenna 123 is located on the second substrate edge 102 of the circuit board 100 and the third main beam direction is opposite to the first main beam direction.

While in FIG. 2 the third antenna 123 is located on the second substrate edge 102, it shall be understood that the third antenna 123 may be also located on the first substrate edge 101, and the third main beam direction may be opposite to the second main beam direction.

Optionally, as another embodiment, the plurality of antennas further comprises: a fourth antenna, located on the first substrate edge of the circuit board and configured to produce a fourth radiation pattern with a fourth main beam direction opposite to the second main beam direction.

According to embodiments of the present invention, the third antenna 123 has at least one tapered edge which is along with second substrate edge, and the fourth antenna has at least one tapered edge which is along the first substrate edge. In other words, the antenna structures include a tapered edge in the direction of a radiation sector which is along the edge of the circuit board.

For example, referring to FIG. 2, the third antenna 123 has two tapered edges. Specifically, referring to FIG. 11, the third antenna 123 has a first tapered edge 1110, a second tapered edge 1120, a third edge 1130 and a fourth edge 1140, wherein the third edge 1130 has a trapezium bulge 1131, the fourth edge 1140 has a groove, a bottom of the groove has a rectangle bulge 1141, each side wall of the groove has a L-shape groove 1142, the top center of the trapezium bulge 1141 is connected to the ground layer 114 and the top center of the rectangle bulge 1131 is connected to a third feed port 113, and the fourth edge 1140 is perpendicular to the first main beam direction.

The angle φ between the first tapered edge 1110 and the second tapered edge 1120 may be set to 40 degree, and the embodiments of the present invention are not limited thereto, for example, the angle φ may be set as other degrees as required. According to a result of simulation, when the angle φ is 90 degree, full coverage of the antennas is realized with better coverage performance.

According to embodiments of the present invention, the third antenna has an elevation angle in respect to a ground layer of the circuit board. In other words, circuit board-mounted antenna structures, having a tapered edge in the direction of a primary radiation sector of space, and having an elevation angle in respect to the circuit board in the direction of a secondary radiation sector of space.

For example, in the third antenna of FIG. 12, the elevation angle in respect to the plane of the substrate may be set to any value between 0 degree and 45 degree. For example in an embodiment of the present invention, a value of the elevation angle may be established to 23 degree, so that feed port impedance matching and radiation pattern coverage can be optimal.

According to embodiments of the present invention, each of the plurality of antennas has load blocks, located between the substrate and a radiator of the antenna, and configured to support the antenna, wherein the load blocks are conductive so that the antenna is designed in reduced size. The blocks have effects of lowering operation wavelength of the antenna and serving as mechanical support to enhance mechanical reliability of the antenna mounting on the substrate.

The embodiments of the present invention improve the performance wireless coverage when the antennas are mounted on a circuit board of a communication device and particularly when these antennas are closely spaced and positioned at one corner of the circuit board. New antenna geometries and configurations are introduced to allow for better shaping of individual antenna radiation patterns and achieve full coverage void of blind sectors and deep null angles where signal reception would otherwise not be possible.

It will be apparent to anyone skilled in the art that the antenna structures here disclosed may be used, arranged, applied independently or collectively in configuration scenarios different from those explicitly illustrated within the scope of the present invention. For example, the antenna structures may be coupled to a radio switching device which is able to select one or more of the antennas and concentrate radiation only in the directions of the intended receivers while eliminating interferences originating from devices located in other directions.

FIG. 3 illustrates a schematic diagram of antenna structures according to another embodiment of the present invention. The circuit board 200 is an example of the circuit board 100. The antenna structures include a plurality of antennas collocated at a corner of a circuit board 200 of a communication device. FIG. 13 illustrates a vertical view of the third antenna in FIG. 3. FIG. 14 illustrates a side view of the third antenna in FIG. 3.

Referring to FIG. 3, the third antenna 223 has one tapered edge. Specifically, referring to FIG 13, the third antenna 223 has a first edge 1310, a second tapered edge 1320, a third edge 1330 and a fourth edge 1340. The first edge 1310 runs parallel to the second substrate edge 202, the third edge 1330 is perpendicular to the second substrate edge 202, the fourth edge 1340 has a groove. A first connection point G of the fourth edge 1340 and the third edge 1330 is connected to the ground layer 214 and a second connection point F of the fourth edge 1340 and the second tapered edge 1320 is connected to a third feed port 213.

Referring to FIG. 13 and FIG. 14, the antenna 223 has

blocks

233 and 237, located between the substrate 210 and a radiator of the antenna 223, and configured to support the antenna 223, wherein the load blocks 233 and 237 are conductive so that the antenna 223 is designed in reduced size.

FIG. 4 illustrates a schematic diagram of antenna structures at a corner of a circuit board 400 according to another embodiment.

Referring to FIG. 4, the antenna structures including a plurality of antennas are collocated at a corner of a circuit board 400, and various communication circuit modules are mounted on a substrate 410 of the circuit board 400. For example, the communication circuit modules may include may include MIMO Processor Module 440, Radio Frequency Module 450, Data Input/Output Module 460 and Power Source Module 470. Radio Frequency Module 450 may be mounted around the corner at which the plurality of antennas is located so that the antennas are connected to the Radio Frequency Module 450 through microstrip transmission lines.

Referring to FIG. 4, the first main beam direction is –X direction, the second main beam direction is +X direction, the third main beam direction is +Y direction, and the fourth main beam direction is –Y direction.

Since the antennas are collocated at one corner of the circuit board, the Radio Frequency Module 450 can be arranged near the antennas. In this case, a shorter microstrip transmission line may be used to connect the Radio Frequency Module 450 and the antennas, thus improving the signal quality of the antennas.

FIG. 5 illustrates a schematic diagram of a circuit board 400 according to an embodiment of the present invention. The circuit board 400 is an example of the circuit board 100. FIG. 11 illustrates a vertical view of the third antenna in FIG. 5.

The circuit board 400 includes a first antenna 121, a second antenna 122, a third antenna 423 and a fourth antenna 424. The third antenna 423 is located on the second substrate edge 202 of the circuit board 400, configured to produce a third radiation pattern with a third main beam direction, and the third main beam direction is opposite to the first main beam direction. The geometry of the fourth antenna is similar to that of the third antenna in FIG. 5.

The fourth antenna 424 is located on the first substrate edge 201 of the circuit board 400 and configured to produce a fourth radiation pattern with a fourth main beam direction opposite to the second main beam direction. The fourth antenna has two tapered edges which are along the first substrate edge.

FIG. 6 illustrates a schematic diagram of a circuit board 500 according to another embodiment of the present invention. The circuit board 500 is an example of the circuit 100. The circuit board 500 includes a first antenna 121, a second antenna 122, a third antenna 223 and a four antenna 524. The geometry of the fourth antenna 524 is similar to that of the third antenna 223 in FIG. 13.

The fourth antenna 524 is located on the first substrate edge 501 of the circuit board 500 and configured to produce a fourth radiation pattern with a fourth main beam direction opposite to the second main beam direction. The fourth antenna 524 has one tapered edge which is along with first substrate edge 501.

FIG. 7 illustrates a schematic diagram of antenna structures at a corner of a circuit board 700 according to another embodiment.

Referring to FIG. 7, the antenna structures including a plurality of antennas are collocated at a corner of a circuit board 700, and various communication circuit modules are mounted on a substrate 710 of the circuit board 700 may include MIMO Processor Module 740, Radio Frequency Module 750, Data Input/Output Module 760 and Power Source Module 770. Radio Frequency Module 750 may be mounted around the corner at which the plurality of antennas is located so that the plurality of antennas may be connected to the Radio Frequency Module 750 through a microstrip transmission line.

Referring to FIG. 7, the first main beam direction is –X direction, the second main beam direction is +X direction, and the third main beam direction has direction components in +X direction and –Y direction.

Since the antennas are collocated at one corner of the circuit board, the Radio Frequency Module 750 can be arranged near the antennas. In this case, a shorter microstrip transmission line may be used to connect the Radio Frequency Module 750 and the antennas, thus improving the signal quality of the antennas.

FIG. 8 illustrates a schematic diagram of a circuit board 700 according to another embodiment of the present invention. The geometry of the third antenna 723 is similar to that of the third antenna 123 in FIG. 2.

According to embodiments of the present invention, the first antenna 121, the second antenna 122 and the third antenna 723 are collocated at the corner of the circuit board 700. The third antenna 723 is located between the first substrate edge 701 and the second substrate edge 702, and the third main beam direction has direction components opposite to the first main beam direction and the second main beam direction, for example, the third antenna 723 may be located on the angle bisector of the corner.

FIG. 9 illustrates a vertical view of the second antenna in FIG. 2. FIG. 10 illustrates a side view of the second antenna in FIG. 9. In FIG. 9, the second antenna 122 in FIG. 2 is taken as an example. The geometry of the first antenna in FIG. 2 is similar to that of the second antenna 122.

Referring to FIG. 9 and FIG. 10, the second antenna 122 is a planar loop type metallic radiator mounted a short distance above the circuit board and at one edge of the circuit board. The circuit board comprises a top ground layer and a bottom ground layer. The antenna 122 is inserted in the circuit board 100 by two conducting pins； one conducting pin, ‘G’ , is connected to both ground layers. Another conducting pin, ‘F’ , is connected to a radio signal feed port 112 and is isolated from both ground layers through a carved feature cut from the ground layers as shown in FIG. 9. Two additional pins, ‘size reduction loads’ , 132 and 136 may be employed to reduce the effective operation wavelength of the antenna 122 at the desired frequency and also serve as mechanical fixtures to stabilize the antenna 122 horizontally above the circuit board and maintain horizontal polarized radiated energy in respect to the circuit board ground plane.

FIG. 12 illustrates a schematic diagram of antenna structures according to another embodiment of the present invention. In FIG. 12, the antenna 123 in FIG. 2 is taken as an example.

Referring to FIG. 12, the antenna 123 includes a radiator 1210 and a first bracket 1220 and a second bracket 1230. The second bracket 1220 is higher than the first bracket 1220 so that the radiator 1210 has an elevation angle θ in respect to the substrate 1240. The first bracket 1220 is configured to support the radiator 1210 and connect the radiator 1210 to the ground layer at the point G on the two sides of the substrate 1240. The second bracket 1230 is configured to support the radiator 1210 and connect the radiator 1210 to the feed port at the point F on the substrate 1240.

Referring to FIG. 12, the antenna having a vertical tapered shape produces a radiation pattern with broad coverage in an azimuthal plane and tilted towards the direction specified by the orientation angle θ labeled in FIG. 12. According to the result of simulation, the antennas may yield complementary radiation patterns with average efficiency above 70％ across the 5GHz～6GHz WLAN band, and full coverage is thus realized with satisfactory coverage gain void of deep null angles.

FIG. 15 illustrates a schematic diagram of a circuit board 1500 according to another embodiment of the present invention.

The circuit board 1500 includes a substrate 110； a plurality of

feed ports

111, 112 and 113, arranged in the substrate 110； a ground 114, arranged on the substrate 110； and antenna structures according to the above embodiments coupled to the plurality of

feed ports

111, 112 and 113, respectively and coupled to a ground.

Optionally, as another embodiment, the circuit board 100 further includes a radio frequency module 1550, coupled to the antenna structures, and configured to modulate and demodulate a radio signal received by the antenna structures, wherein the antenna structures are coupled to the radio frequency module through micro transmission lines.

According to embodiments of the present invention, the dimensions and the geometry of the antennas in the antenna structure may be chosen so that the antennas operate at the intended frequency bands, and the dimensions of the antennas established accordingly, using design tools such as electromagnetic simulation solvers. For example, the antennas may be designed to operate at wireless local area network (WLAN) bands. When the antennas operate at the 5 GHz WLAN band for example, the dimensions of the antennas may be chosen so as to fully cover the 5.15 GHz -5.8 GHz spectrum with each antenna port reflection coefficient below -10 dB, with mutual coupling below -20 dB and with the desired radiation characteristics.

According to embodiments of the present invention, a communication device including a circuit board as described in the above embodiments is provided.

The communication device may be but not limited to a mobile terminal or a personal wireless device, e.g., a desktop, laptop, phone, tablet, or the like.

In the embodiments of present invention, new radiating structures and multi-antenna configurations are introduced to achieve full MIMO wireless coverage with collocated antennas. In the presence of the other radiators, the form factor of each antenna is modeled so that the antenna concentrates radiation into a specific portion of space by constructively coupling to the circuit board ground plane. In this way, the radiation pattern of each antenna is shaped to be complementary to the radiation patterns of the other ones in a multi-antenna configuration. Thus the full wireless coverage is realized by combining the individual complementary patterns from the constitutive antenna elements of the multi-antenna system.

One advantage of the present invention is that antenna directional gain is realized without relying on extra geometry structures like directors and reflectors conventionally used in a typical small directional antennas technique. Another advantage of the invention is design simplicity and cost effectiveness because it eliminates the need for expensive coax cables to connect the antennas. Furthermore, since the antennas are closely spaced, only short microstrip transmission lines are needed to couple the antennas to a radio frequency module, and thus avoiding the use of long microstrip lines which would otherwise degrade signal quality

The foregoing descriptions are merely specific embodiments of the invention, rather than limiting the protection scope of the invention. It is easy for any one skilled in the art to conceive changes or substitutions within the technical scope disclosed by the invention, and the changes or substitutions shall fall in the protection scope of the invention. Therefore, the protection scope of the present invention shall be defined by the claims.

Claims

Multiple input multiple output wireless antenna structures, comprising:

a plurality of antennas, collocated at a corner of a substrate of a circuit board and configured to produce complementary radiation patterns with different main beam directions to realize a synthetic full coverage pattern, wherein the plurality of antennas comprises at least three antennas which are coupled to a plurality of feed ports of the circuit board, respectively, and coupled to a ground of the circuit board.
The multiple input multiple output wireless antennas structures according to claim 1, wherein the plurality of antennas comprises:

a first antenna, located on a first substrate edge of the circuit board and configured to produce a first radiation pattern with a first main beam direction which is perpendicular to the first substrate edge；

a second antenna, located on a second substrate edge of the circuit board and configured to produce a second radiation pattern with a second main beam direction which is perpendicular to the second substrate edge；

a third antenna, configured to produce a third radiation pattern with a third main beam direction.
The multiple input multiple output wireless antenna structures according to claim 2, wherein the third antenna is located on the second substrate edge of the circuit board and the third main beam direction is parallel to the second substrate edge and opposite to the first main beam direction,

or,

the third antenna is located on the first substrate edge of the circuit board and the third main beam direction is opposite to the second main beam direction.
The multiple input multiple output wireless antenna structures according to claim 3, wherein the plurality of antennas further comprises:

a fourth antenna, located on the first substrate edge of the circuit board and configured to produce a fourth radiation pattern with a fourth main beam direction opposite to the second main beam direction.
The multiple input multiple output wireless antenna structures according to claim 4, wherein the third antenna has at least one tapered edge which is along the second substrate edge, and the fourth antenna has at least one tapered edge which is along the first substrate edge.
The multiple input multiple output wireless antenna structures according to claim 5, wherein the third antenna has a first tapered edge, a second tapered edge, a third edge and a fourth edge, wherein the third edge has a trapezium bulge, the fourth edge has a groove, a bottom of the groove has a rectangle bulge, each side wall of the groove has a L shape groove, the top center of the trapezium bulge is connected to the ground layer and the top center of the rectangle bulge is connected to a third feed port, and the fourth edge is perpendicular to the first main beam direction.
The multiple input multiple output wireless antenna structures according to claim 5, wherein the third antenna has a first edge, a second tapered edge, a third edge and a fourth edge, wherein the first edge runs parallel to the second substrate edge, the third edge is perpendicular to the second substrate edge, the fourth edge has a groove, a first connection point of the fourth edge and the third edge is connected to the ground layer and a second connection point of the fourth edge and the second tapered edge is connected to a third feed port.
The multiple input multiple output wireless antenna structures according to any of claims 2-7, wherein the third antenna has an elevation angle in respect to a ground layer of the circuit board.
The multiple input multiple output wireless antenna structures according to claim 2, wherein the third antenna is located between the first substrate edge and the second substrate edge, and the third main beam direction has direction components opposite to the first main beam direction and the second main beam direction.
The multiple input multiple output wireless antenna structures according to claim 2 or 9, wherein the third antenna has a tapered edge.
The multiple input multiple output wireless antenna structures according to claim 10, wherein the third antenna has a first tapered edge, a second tapered edge, a third edge and a fourth edge, wherein the third edge has a trapezium bulge, the fourth edge has a groove, a bottom of the groove has a rectangle bulge, each side wall of the groove has a L shape groove, the top center of the trapezium bulge is connected to the ground layer and the top center of the rectangle bulge is connected to a third feed port, and the fourth edge is perpendicular to the first main beam direction.
The multiple input multiple output wireless antenna structures according to claim 10, wherein the third antenna has a first edge, a second tapered edge, a third edge and a fourth edge, wherein the first edge runs parallel to the second substrate edge, the third edge is perpendicular to the second substrate edge, the fourth edge has a groove, a first connection point of the fourth edge and the third edge is connected to the ground layer and a second connection point of the fourth edge and the second tapered edge is connected to a third feed port.
The multiple input multiple output wireless antenna structures according to any of claims 2-12, wherein each of the plurality of antennas has load blocks, located between the substrate and the antenna, and configured to support the antenna, wherein the load blocks are conductive so that the antenna is designed in reduced size.
The multiple input multiple output wireless antenna structures according to any of claims 2-13, wherein the third antenna has an elevation angle in respect to a ground layer of the circuit board.
The multiple input multiple output wireless antenna structures according to any of claims 2-14, wherein each of the first antenna and the second antenna is of planar loop type.
The multiple input multiple output wireless antenna structures according to any of claims 2-15, wherein the plurality of antennas comprises dual polarization antennas to realize a dual-polarization pattern coverage.
A communication device, comprising: a circuit board, wherein the circuit board comprises:

a substrate；

a plurality of feed ports, arranged in the substrate；

a ground, arranged on the substrate；

multiple input multiple output wireless antenna structures according to any of claims 1-16, coupled to the plurality of feed ports, respectively and coupled to a ground of the circuit board.
The communication device according to claim 17, wherein the circuit board further comprises:

a radio frequency module, coupled to the plurality of antennas, and configured to modulate and demodulate a radio signal received by the plurality of antennas, wherein the plurality of antennas are coupled to the radio frequency module through micro transmission lines.