Wireless communication device comprising a dual-band antenna for satellite communication

Abstract

A compact antenna structure for a (mobile) wireless communication device is provided, which can operate in two frequency bands, while exhibiting maximum end-fire radiation therein. The antenna is a frame portion of a conductive frame in the wireless communication device and capacitively fed by a feeding structure comprising a conductive strip, a first conductive element, and a second conductive element. The strip is spaced from and extends substantially parallel to the frame portion. The strip is connected to a wireless communication module provided in the wireless communication device. The elements are spaced from the strip and from each other, and each of them has an L-shaped profile comprising a long section and a short section. The long sections extend substantially parallel to the frame portion towards each other, while the short sections extend at an angle to the frame portion to provide contact between the elements and the frame portion.

Description

[0001] WIRELESS COMMUNICATION DEVICE COMPRISING A DUAL-BAND ANTENNA FOR SATELLITE COMMUNICATION

[0002] TECHNICAL FIELD

[0003] The present disclosure relates generally to the field of wireless communications. In particular, the present disclosure relates to a wireless communication apparatus comprising a compact dual-band antenna suitable for satellite communication.

[0004] BACKGROUND

[0005] More and more radio technologies need to be supported in a mobile device. These technologies may include cellular technologies, such as 2G / 3G / 4G radio, as well as non-cellular technologies, such as Wi-Fi. In the 5G new radio (NR) technology, the operational frequency range is expanded from the so-called sub-6 GHz to the millimetre wave (mmWave) frequency range, e.g., between 20 GHz and 70 GHz.

[0006] Due to the continuous development of satellite communication technology, satellite communication will be an important component of future 6G communication technology. However, the satellite communication technology is different from the cellular one and has different antenna requirements. This has raised the problem of coexistence of cellular and satellite communication systems in mobile devices (e.g., mobile phones). Especially in today's environment where the mobile devices are gradually getting smaller and lighter, it is necessary to provide both cellular and satellite communications.

[0007] In satellite communication, a circularly polarised antenna capable of transmitting and receiving a circularly polarised signal is commonly used. The circularly polarised signal can attenuate interference and fading caused by multipath propagation. However, the circularly polarised antenna usually requires a large volume, and it is difficult to install such an antenna in a wearable electronic device. Therefore, a linearly polarised antenna is usually used to receive and transmit linearly polarised signals of a wearable electronic device. Since the polarisation modes of linearly polarised and circularly polarised signals are different, energy loss due to polarisation mismatch occurs during communication between the linearly polarised antenna and the circularly polarised antenna, and thus the communication quality between the electronic device and a communication satellite is degraded. The development of polarised satellite communication antennas with high gain and wide beam coverage becomes even more challenging.

[0008] Thus, additional engineering is required to develop a compact antenna design that can be efficiently used for satellite communication.

[0009] SUMMARY

[0010] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure.

[0011] It is an objective of the present disclosure to provide a compact antenna for a wireless communication device that can operate in two different frequency bands (e.g., downlink and uplink for satellite communication), with maximum radiation in the endfire direction in each of the bands.

[0012] The objective above is achieved by the features of the independent claim in the appended claims. Further embodiments and examples are apparent from the dependent claims, the detailed description, and the accompanying drawings.

[0013] According to an aspect, a wireless communication device is provided, which comprises a grounding plate, a printed circuit board, a conductive frame, and a feeding structure. The printed circuit board is arranged on the grounding plate and comprises a wireless communication module. The conductive frame extends along edges of the grounding plate and comprises a first frame portion and a second frame portion which are separated from each other. The feeding structure is configured to capacitively feed the first frame portion of the conductive frame with a feeding signal. The feeding structure comprises a conductive strip, a first conductive element, and a second conductive element. The conductive strip is spaced from and extends substantially parallel to the first frame portion of the conductive frame. The conductive strip is connected to the wireless communication module. The first conductive element is spaced from the conductive strip and has an L-shaped profile comprising a long section and a short section. The second conductive element is spaced from each of the conductive strip and the first conductive element and has an L-shaped profile comprising a long section and a short section. The long sections of the first conductive element and the second conductive element extend substantially parallel to the first frame portion of the conductive frame towards each other. At the same time, the short sections of the first conductive element and the second conductive element extend at an angle to the first frame portion of the conductive frame such that the first conductive element and the second conductive element are in contact with the first frame portion of the conductive frame. In the wireless communication device thus configured, the first frame portion of the conductive frame may be used as a capacitively fed antenna capable of operating in two frequency bands suitable for satellite communication and maintaining maximum end-fire radiation therein. Moreover, such an antenna design is compact in size, for which reason it may be installed (e.g., together with other antennas for cellular communication) in a mobile electronic device, such as a mobile phone, a smartphone, etc.

[0014] In one exemplary embodiment, the long sections of the first conductive element and the second conductive element are aligned with each other. This may make the antenna structure more compact in size.

[0015] In one alternative exemplary embodiment, the long sections of the first conductive element and the second conductive element partly overlap each other. This embodiment may be beneficial when it is infeasible to align the long sections of the first and second conductive elements, for example, due to the internal design (e.g., other structural elements, such as any other antenna, a battery, a camera, different sensors, etc.) of the device itself.

[0016] In one exemplary embodiment, the conductive strip, the first conductive element and the second conductive element are spaced from the first frame portion and from each other by a dielectric material. The dielectric material may be used to tune the operational frequency of the first frame portion acting as the capacitively fed antenna. Moreover, the presence of the dielectric material may make the whole antenna structure more mechanically durable and stable.

[0017] In one exemplary embodiment, the conductive frame further comprises a third frame portion separated from each of the first frame portion and the second frame portion. The third frame portion is arranged opposite to the second frame portion, and each of the third frame portion and the second frame portion has a phase center spaced from a phase center of the first frame portion at a distance equal to a half- wavelength of an electromagnetic wave to be radiated by the first frame portion. In this embodiment, the second and third frame portions may be used as passively fed antennas whose radiation beams may positively influence the radiation beam of the first frame portion (i.e., the actively fed antenna) by making it wider in the end-fire direction at higher frequencies.

[0018] In one alternative exemplary embodiment, the phase center of each of the third frame portion and the second frame portion is spaced from the phase center of the first frame portion at a distance other than the half- wavelength of the electromagnetic wave to be radiated by the first frame portion. In this embodiment, the device further comprises a coupling structure configured to couple a part of the feeding signal from the first frame portion to each of the second frame portion and the third frame portion so as to cause the second frame portion and the third frame portion to radiate electromagnetic waves having a phase difference of 180 degrees and an equal amplitude (which is preferably 3 dB less than the one provided to the first frame portion). In this alternative embodiment, the coupling structure allows the second and third frame portions to be used as passively fed antennas whose radiation beams may also positively influence the radiation beam of the first frame portion (i.e., the actively fed antenna) by making it wider in the end-fire direction at higher frequencies. Furthermore, this alternative embodiment may be beneficial when the distance between the first frame portion and each of the second and third frame portions cannot be changed (to meet the half-wavelength requirement mentioned above) due to the internal device design (e.g., the presence of other structural elements) and / or for other manufacturing purposes.

[0019] In one exemplary embodiment, the coupling structure comprises a first sub-structure and a second sub-structure. The first substructure comprises a first conductive track and a second conductive track connected to the first conductive track. The first conductive track extends substantially parallel to the first frame portion, while the second conductive track extends substantially parallel to the second frame portion. The second sub-structure comprises a third conductive track and a fourth conductive track connected to the third conductive track. The third conductive track extends substantially parallel to the first frame portion and is spaced from the first conductive track, while the fourth conductive track extends substantially parallel to the third frame portion. By using this coupling structure, it is possible to properly (as described above) branch the part of the feeding signal to each of the second and third frame portions.

[0020] In one exemplary embodiment, the coupling structure further comprises a third conductive element, a fourth conductive element, a fifth conductive element, and a sixth conductive element. The third to sixth conductive elements are spaced from each other, and each of the third to sixth conductive elements has an L-shaped profile comprising a long section and a short section. The long sections of the third conductive element and the fourth conductive element extend substantially parallel to the second frame portion towards each other, and the short sections of the third conductive element and the fourth conductive element extend at an angle to the second frame portion such that the third conductive element and the fourth conductive element are in contact with the second frame portion. The long sections of the fifth conductive element and the sixth conductive element extend substantially parallel to the third frame portion towards each other, and the short sections of the fifth conductive element and the sixth conductive element extend at an angle to the third frame portion such that the fifth conductive element and the sixth conductive element are in contact with the third frame portion. The use of these conductive elements in the coupling structure allows for a stronger capacitive coupling of the first sub-structure to the second frame portion and the second substructure to the third frame portion, thereby making the radiation beam of the first frame portion even wider at higher frequencies.

[0021] Other features and advantages of the present disclosure will be apparent upon reading the following detailed description and reviewing the accompanying drawings.

[0022] BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present disclosure is explained below with reference to the accompanying drawings in which:

[0024] FIGs. 1A and IB show a simplified antenna design environment of a mobile phone and a metal frame antenna, respectively, in accordance with the prior art;

[0025] FIGs. 2A and 2B schematically show the distribution of currents in the metal frame antenna of FIG. IB in a wire differential mode and a wire common mode, respectively;

[0026] FIGs. 3A and 3B show beam patterns of the metal frame antenna of FIG. IB in the wire differential mode and the wire common mode, respectively;

[0027] FIGs. 4A and 4B show different schematic views of a dual-band antenna according to a first exemplary embodiment, namely: FIG. 4A shows an isometric view of the dual-band antenna, and FIG. 4B shows a top view of the dual-band antenna;

[0028] FIG. 5 shows return loss of the dual-band antenna according to the first exemplary embodiment;

[0029] FIGs. 6A and 6B schematically show the distribution of currents in the dual-band antenna according to the first exemplary embodiment in a low-band wire differential mode and a high-band two-slot common mode in phase, respectively; FIGs. 7A and 7B show beam paterns of the dual-band antenna according to the first exemplary embodiment in low and high bands, respectively;

[0030] FIG. 8 shows a schematic isometric sectional view of a dual-band antenna according to a second exemplary embodiment, in which the dual-band antenna is covered with a dielectric material;

[0031] FIG. 9 shows a schematic top view of a dual-band antenna according to a third exemplary embodiment, in which two passively fed side antenna elements are used to increase the beam width of an actively fed top antenna element;

[0032] FIG. 10 shows a schematic top view of a dual-band antenna according to a fourth exemplary embodiment, in which two passively fed side antenna elements are used to increase the beam widths of two actively fed top antenna elements;

[0033] FIG. 11 schematically illustrates a situation when the passively fed side antenna elements of the dual-band antenna according to the third exemplary embodiment are not optimally located relative to the actively fed top antenna element, thereby resulting in a reduced antenna beam width at higher frequencies;

[0034] FIGs. 12A and 12B show different antenna far-field visualizations as a 2D map far-field plot and a 3D far-field plot for the situation of FIG. I r respectively;

[0035] FIG. 13 shows a schematic top view of a dual-band antenna according to a fifth exemplary embodiment, in which a coupling structure is used to combat the problem of the decreased antenna beam width in the situation of FIG. 11;

[0036] FIGs. 14A and 14B show different antenna far-field visualizations simulated for the dual-band antenna according to the fifth exemplary embodiment as a 2D map far-field plot and a 3D far-field plot, respectively;

[0037] FIGs. 15A-15C show different schematic views of a dual-band antenna according to a sixth exemplary embodiment, namely: FIG. 15A shows an isometric view of the dual-band antenna, FIG. 15B shows a top view of the dual-band antenna, and FIG. 15C shows an isometric sectional view of a coupling structure used in the dual-band antenna; and

[0038] FIGs. 16A-16C show beam patterns for different cases, namely: FIG. 16A shows the beam paterns with (dashed line) and without (solid line) the coupling structure used in the dual-band antenna according to the sixth exemplary embodiment at a low frequency of 1.95 GHz, FIG. 16B shows the beam paterns for the dual-band antenna according to the sixth exemplary embodiment without the coupling structure at three higher frequencies (i.e., 3.5 GHz, 3.55 GHz and 3.6 GHz), and FIG. 16C shows the beam patterns for the dual-band antenna according to the sixth exemplary embodiment with the coupling structure at the same higher frequencies.

[0039] DETAILED DESCRIPTION

[0040] Various embodiments of the present disclosure are further described in more detail with reference to the accompanying drawings. However, the present disclosure may be embodied in many other forms and should not be construed as limited to any certain structure or function discussed in the following description. In contrast, these embodiments are provided to make the description of the present disclosure detailed and complete.

[0041] According to the detailed description, it will be apparent to the ones skilled in the art that the scope of the present disclosure encompasses any embodiment thereof, which is disclosed herein, irrespective of whether this embodiment is implemented independently or in concert with any other embodiment of the present disclosure. For example, the device disclosed herein may be implemented in practice by using any numbers of the embodiments provided herein. Furthermore, it should be understood that any embodiment of the present disclosure may be implemented using one or more of the features presented in the appended claims. The word “exemplary” is used herein in the meaning of “used as an illustration”. Unless otherwise stated, any embodiment described herein as “exemplary” should not be construed as preferable or having an advantage over other embodiments.

[0042] Any positioning terminology, such as “left”, “right”, “top”, “bottom”, “above” “below”, “upper”, “lower”, “horizontal”, “vertical”, etc., may be used herein for convenience to describe one element’s or feature's relationship to one or more other elements or features in accordance with the figures. It should be apparent that the positioning terminology is intended to encompass different orientations of the apparatus disclosed herein, in addition to the orientation(s) depicted in the figures. As an example, if one imaginatively rotates the apparatus in the figures 90 degrees clockwise, elements or features described as “left” and “right” relative to other elements or features would then be oriented, respectively, “above” and “below” the other elements or features. Therefore, the positioning terminology used herein should not be construed as any limitation of the present disclosure.

[0043] Furthermore, although the numerative terminology, such as “first”, “second”, etc., may be used herein to describe various embodiments, elements or features, it should be understood that these embodiments, elements or features should not be limited by this numerative terminology. This numerative terminology is used herein only to distinguish one embodiment, element or feature from another embodiment, element or feature. For example, a first conductive element discussed below could be called a second conductive element, and vice versa, without departing from the teachings of the present disclosure.

[0044] As used in the embodiments disclosed herein, a dual-band antenna may refer to a device configured to radiate and receive radio waves in two different (low and high) frequency bands, e.g., with one suitable for uplink satellite communication and the other suitable for downlink satellite communication. The dual-band antenna is also assumed to be implemented as part of a conductive (e.g., metal) frame of a (mobile) user device or user equipment (UE). The dual-band antenna can be combined with any other antennas on the same frame (such as mid-band, high-band, low-band antennas, etc.). Such an antenna is also referred to as a (metal) frame antenna in the art. As for the UE, it may refer to a wireless customer premises equipment (CPE) (e.g., a wireless router, switch, etc.), a mobile device, a mobile station, a terminal, a subscriber unit, a mobile phone, a cellular phone, a smart phone, a cordless phone, a personal digital assistant (PDA), a wireless communication device, a laptop computer, a tablet computer, a desktop computer, a single-board computer (SBC) (e.g., a Raspberry Pi device), a gaming device, a netbook, a smartbook, an ultrabook, a medical device or medical equipment, a biometric sensor, a wearable device (e.g., a smart watch, smart glasses, a smart wrist band, etc.), an entertainment device (e.g., an audio player, a video player, etc.), a vehicular component or sensor (e.g., a driver-assistance system), a smart meter / sensor, an unmanned vehicle (e.g., an industrial robot, a quadcopter, etc.) and its component (e.g., a self-driving car computer), industrial manufacturing equipment, a global positioning system (GPS) device, an Intemet-of-Things (loT) device, an Industrial loT (IIoT) device, a machine-type communication (MTC) device, a group of Massive loT (MIoT) or Massive MTC (mMTC) devices / sensors, or any other suitable device that uses the radio waves for operation. In some embodiments, the UE may refer to at least two collocated and inter-connected UEs thus defined.

[0045] FIGs 1A and IB show a simplified antenna design environment of a mobile phone 100 and a metal frame antenna, respectively, in accordance with the prior art. More specifically, the mobile phone 100 comprises a grounding plate (not shown), a printed circuit board (PCB) 102 provided on the grounding plate and having a wireless communication module 104 provided thereon, and a metal frame 106 extending along the edges of the grounding plate and, consequently, the PCB 102. The PCB may also carry a battery 108. The metal frame 106 is cut to form a few opening slots 110, so that one or more separated frame portions can be formed and used, when properly fed, as radiating elements or antennas. For example, it is assumed that a top frame portion 112 serves a galvanically and / or capacitively fed dual-band antenna whose structure is shown in FIG. IB. There may also be a few connection points 114 between the metal frame 106 and the PCB 102 and / or between the metal frame 106 and the grounding plate to create grounding points for the dual-band antenna. As shown in FIG. IB, the dual-band antenna implemented based on the top frame portion 112 may be galvanically fed via metal contacts 116 attached to the top frame portion 112 and / or capacitively fed via a feeding structure comprising a metal strip 118 having a metal contact 120 attached to one (right) of its ends and connected to the wireless communication module 104. The metal strip 118 is spaced from and extends substantially parallel to the top frame portion 112 of the metal frame 106. Such a frame antenna can be considered as a monopole / dipole antenna configured to operate in a wire differential mode at a low frequency and a wire common mode at a high frequency.

[0046] FIGs 2A and 2B schematically show the distribution of currents in the metal frame antenna of FIG. IB in the wire differential mode and the wire common mode, respectively. As can be seen, in the wire differential mode (see FIG. 2A), the currents are in the same direction in the antenna, while they are in opposite directions in the wire common mode (see FIG. 2B).

[0047] FIGs 3A and 3B show beam patterns of the metal frame antenna of FIG. IB in the wire differential mode and the wire common mode, respectively. These beam patterns clearly show the main disadvantage of the prior art metal frame antenna, which consists in that at higher frequency (corresponding to the wire common mode), the beam patterns give deep zero radiation in the theta 0 degree direction (see FIG. 3B). This means that such an antenna cannot be efficiently used for satellite communication.

[0048] The exemplary embodiments disclosed herein provide a technical solution that allows eliminating the above-described drawback peculiar to the prior art. More specifically, the technical solution refers to a compact antenna for a (mobile) wireless communication device that can operate in two different frequency bands corresponding to satellite communication, while exhibiting maximum end-fire radiation in each of the bands (i.e., such an antenna does not give deep zero radiation in the theta 0 degree direction at higher frequencies). The antenna itself is implemented based on a frame portion of a conductive frame in the wireless communication device and capacitively fed by means of a feeding structure. The feeding structure comprises a conductive strip, a first conductive element, and a second conductive element. The conductive strip is spaced from and extends substantially parallel to the frame portion. The conductive strip is connected to a wireless communication module provided in the wireless communication device. The first and second conductive elements are spaced from the conductive strip and from each other, and each of them has an L-shaped profile comprising a long section and a short section. The long sections of the first and second conductive elements extend substantially parallel to the frame portion towards each other, while their short sections extend at an angle to the frame portion such that the first and second conductive elements are in contact with the frame portion.

[0049] FIGs 4A and 4B show different schematic views of a dual-band antenna according to a first exemplary embodiment. More specifically, FIG. 4A shows an isometric view of the dual-band antenna, and FIG. 4B shows a top view of the dual-band antenna. The dual-band antenna according to the first exemplary embodiment is assumed to be implemented based on the top frame portion 112 of the mobile phone 100. In general, the dual-band antenna according to the first exemplary embodiment is implemented as the one shown in FIG. IB, but with one addition: the feeding structure further comprises two L-shaped conductive elements comprising long sections 402, 404 and short sections 406, 408. The conductive elements are arranged inside the mobile phone 100 such that their long sections 402, 404 extend substantially parallel to the top frame portion 112 towards each other and are aligned with each other, while their short sections 406, 408 extend at a (e.g., normal) angle to the top frame portion 112 such that the first and second conductive elements are in contact with the top frame portion 112. It is these conductive elements that allow avoid the above-mentioned problem with zero end-fire radiation at higher frequencies, as will be explained further and shown in the other figures. The conductive strip 118 and the L-shaped conductive elements may be made of the same conductive material (e.g., metal). Some exemplary sizes of the whole antenna structure with the feeding structure are shown in FIG. 4B. As can be seen, the dual-band antenna according to the first exemplary embodiment is compact in size and, consequently, may be easily installed / implemented in a mobile or wearable user device (e.g., mobile phone). It should be noted that the present disclosure is not limited to the implementation of the dual-band antenna based on the top frame portion 112 - in some other embodiments, the same antenna may be implemented based on any other frame portion of the mobile phone 100 (e.g., on a left or right side frame portion, or a bottom frame portion).

[0050] FIG. 5 shows return loss of the dual-band antenna according to the first exemplary embodiment. One can see two well-defined frequency bands: low and high. The high-frequency band is 1.5-2 times higher in frequency than the low-frequency band. Together with capacitive feeding, the proposed antenna structure increases capacitance between the feeding structure and the top frame portion 112 (serving as the dual-band antenna itself) and allows opposite-phase common-mode currents provided by the two slots 110 on either side of the top frame portion 112 (see FIG. 1A) at a high operational frequency to be converted to in-phase common-mode currents.

[0051] FIGs 6A and 6B schematically show the distribution of currents in the dual-band antenna according to the first exemplary embodiment in the low-band wire differential mode and the high-band two-slot common mode in phase, respectively. As can be seen, in both frequency bands, the currents are in the same direction, thereby confirming the conclusion that the proposed feeding structure with the L-shaped conductive elements allows the opposite-phase common-mode currents of the two slots 110 on either side of the top frame portion 112 to be converted to the in-phase common-mode currents at higher frequencies.

[0052] FIGs 7A and 7B show beam patterns of the dual-band antenna according to the first exemplary embodiment in low and high bands, respectively. Since both frequency bands for the proposed antenna solution correspond to the modes when the currents are in the same direction, as shown in FIGs 6A and 6B, both bands provide a desired beam which gives maximum radiation in the end-fire (theta 0 degree) direction in the upper hemisphere of the beam patterns.

[0053] FIG. 8 shows a schematic isometric sectional view of a dual-band antenna according to a second exemplary embodiment. The dual-band antenna according to the second exemplary embodiment is implemented similarly to the one according to the first exemplary embodiment, with one exception that the feeding structure is “recessed” in a dielectric (e.g., plastic) material. Moreover, FIG. 8 shows only the second conductive element (i.e., its long section 404), which is arranged under the conductive strip 118. However, this should not be construed as any limitation of the present disclosure - in some other embodiments, the L-shaped conductive elements may be arranged above the conductive strip 118 (either in the dielectric material or without it), or the L-shaped conductive elements may be arranged in front of or behind the conductive elements. In general, the implementation and arrangement of the L-shaped conductive elements depend on manufacturing capabilities and / or the antenna environment in the mobile phone (e.g., whether there is space for placing the L-shaped conductive elements in front of the conductive strip 118). For similar purposes, the aligned arrangement of the L-shaped conductive may be replaced with their partly overlapping arrangement (e.g., the long sections 402, 404 may be arranged in front of the conductive strip 119, but the long section 402 may be closer to the conductive strip 118 than the long section 404, or vice versa). As for the gap or spacing between the L-shaped conductive elements, the present author has carried out a number of simulations and found that it has no significant influence on the current distributions and, consequently, the antenna beam patterns; in other words, to solve the problem of zero end-fire radiation at higher frequencies, it is just enough to arrange the L-shaped conductive elements in vicinity of (i.e., on the inner side of) that frame portion which should act as a dual-band antenna.

[0054] FIG. 9 shows a schematic top view of a dual-band antenna according to a third exemplary embodiment. As discussed previously, by using the L-shaped conductive elements, it is possible to provide maximum radiation in the end-fire direction for both low- and high-frequency bands, but it should be noted that a radiation beam at a high frequency will be narrower than at a low frequency. To improve the beam width in the high-frequency band, the dual-band antenna according to the third exemplary embodiment may be used. As shown in FIG. 9, the dual-band antenna may be represented as the combination of one actively fed antenna element 900 and two passively fed antenna elements 902, 904 on sides of the conductive frame 106. The antenna element 900 may be configured in the same manner as the dual-band antenna according to the first exemplary embodiment (see FIGs 4A and 4B). As for the side antenna elements 902, 904, they may be implemented based on other frame portions adjacent to and separated from the one where the antenna element 900 is implemented. The side antenna elements 902, 904 may be of any type, e.g., they may refer to other antennas usually used in mobile devices for different purposes. If the side antenna elements 902, 904 are placed such that their phase centers are spaced from a phase center of the antenna element 900 (i.e., the top frame portion) at a distance equal to a half-wavelength of an electromagnetic wave to be radiated by the antenna element 900 (i.e., the top frame portion), they will positively influence the beam of the antenna element 900 by making it wider at higher frequencies.

[0055] FIG. 10 shows a schematic top view of a dual-band antenna according to a fourth exemplary embodiment. In this embodiment, the dual-band antenna is assumed to be implemented as the combination of two actively fed top (slot) antenna elements 1000, 1002 which operate in-phase, and two passively fed side antenna elements. The top antenna elements 1000, 1002 may be configured in the same manner as the dual-band antenna according to the first exemplary embodiment (see FIGs. 4A and 4B). As for the side antenna elements 1004, 1006, they may be implemented based on other frame portions adjacent to and separated from the ones where the top antenna elements 1000, 1002 are implemented. The side antenna elements 1004, 1006 may be of any type, e.g., they may refer to other antennas usually used in mobile devices for different purposes. Again, if the side antenna element 1004 is distanced from the top antenna element 1000 such that their phase centers are spaced from each other at a distance equal to a half-wavelength of an electromagnetic wave to be radiated by the top antenna element 1000, the beam width of the top antenna element 1000 may be increased at higher frequencies. The same is true for the top antenna 1002 and the side antenna element 1006 - if their phase centers are also half- wavelength-spaced from each other, the beam width of the top antenna element 1002 may be increased at higher frequencies.

[0056] FIG. 11 schematically illustrates a situation when the passively fed side antenna elements 902 and 904 of the dual-band antenna according to the third exemplary embodiment (see FIG. 9) are not optimally located relative to the actively fed top antenna element 900, thereby resulting in a reduced antenna beam width at higher frequencies. As discussed previously, the distance between the phase centers of the antenna elements is important to increase the beam width. However, if this distance is already determined by the existing device design and cannot be changed and is longer or shorter than the optimal (half-wavelength) distance, the side antenna elements will be fed differently (see FIG. 11), for which reason their influence on the beam width of the top antenna element 900 may disappear.

[0057] FIGs 12A and 12B show different antenna far-field visualizations for the situation of FIG. 11. These visualizations are obtained for a frequence of 3.5 GHz.

[0058] FIG. 13 shows a schematic top view of a dual-band antenna according to a fifth exemplary embodiment. In this embodiment, the dual-band antenna is assumed to be implemented as the combination of one top antenna element 1300 and two side antenna elements 1302, 1304. The antenna elements 1300, 1302, 1304 may be implemented in the same or similar manner as the antenna elements 900, 902, 904, respectively. It is also assumed that the side antenna elements 1302, 1304 are arranged such as shown in the situation of FIG. 11 (i.e., not at the optimal half-wavelength distance from the top antenna element 1300). The dual-band antenna according to the fifth exemplary embodiment is characterized by that it further comprises a coupling structure 1306 configured to couple a part of a feeding signal capacitively fed to the top antenna element 1300 to each of the side antenna elements 1302, 1304 so as to cause the side antenna elements 1302, 1304 to radiate electromagnetic waves having a phase difference of 180 degrees and an equal amplitude. The amplitude provided to the side antenna elements 1302, 1304 is preferably 3 dB less than the one provided to the top antenna element 1300. By using such a coupling structure, it is possible to combat the problem of the decreased antenna beam width in the situation of FIG. 11.

[0059] FIGs 14A and 14B show different antenna far-field visualizations simulated for the dual-band antenna according to the fifth exemplary embodiment. As can be seen, the antenna beam at the frequency of 3.5 GHz is wider than the one observed at the same frequency but without the coupling structure (see FIGs 12A and 12B). FIGs 15A-15C show different schematic views of a dual-band antenna according to a sixth exemplary embodiment. More specifically, FIG. 15A shows an isometric view of the dual-band antenna, FIG. 15B shows a top view of the dual-band antenna, and FIG. 15C shows an isometric sectional view of a coupling structure used in the dual-band antenna.

[0060] The dual-band antenna according to the sixth exemplary embodiment is assumed to be implemented in a mobile wireless communication device, like the mobile phone 100. Moreover, the dual-band antenna according to the sixth exemplary embodiment may be considered as the combination of one top antenna element, two side antenna elements, and a specially designed coupling structure. The top antenna element is implemented as the dual-band antenna according to the first exemplary embodiment (i.e., based on the frame portion 112 of the conductive frame 106 and the feeding structure constituted by the conductive strip 118 and the two L-shaped conductive elements). The side antenna elements are implemented based on two side frame portions 1500, 1502 separated from the top frame portion 112. The coupling structure is configured to operate in the same manner as the coupling structure 1306 discussed above.

[0061] The coupling structure may be made of a conductive material (e.g., metal) and located on a plastic carrier or back cover lid of the mobile phone 100. The coupling structure comprises two sub-structures each being configured to couple a proper part of the feeding signal from the top antenna element (i.e., the top frame portion 112) to one of the side antenna elements (i.e., the side frame portions 1500, 1502). The first sub-structure comprises a first conductive track 1504 and a second conductive track 1506 connected to the first conductive track 1504. The first conductive track 1504 extends substantially parallel to the top frame portion 112, while the second conductive track 1506 extends substantially parallel to the side frame portion 1500. The second sub-structure comprises a third conductive track 1508 and a fourth conductive track 1510 connected to the third conductive track 1508. The third conductive track 1508 extends substantially parallel to the top frame portion 112 and is spaced from the first conductive track 1504, while the fourth conductive track 1510 extends substantially parallel to the side frame portion 1502. All the tracks 1504, 1506, 1508, 1510 may be arranged at the same level or, as shown in FIGs 15 A and 15 C , the tracks 1504, 1508 may be arranged higher than the tracks 1506, 1510, or vice versa. In general, the arrangement of the tracks 1504, 1506, 1508, 1510 again depends on the inner design of the mobile phone 100.

[0062] If stronger capacitive coupling is needed between the side frame portions 1500, 1502 and the coupling sub-structures, then the coupling structure may further comprise four L-shaped conductive elements which are implemented in a similar manner as the ones shown, for example, in FIGs 4A and 4B. More specifically, there may be two L-shaped conductive elements near (e.g., above or under) the track 1506, with one comprising a long section 1512 and a short section 1514 and the other comprising a long section 1516 and a short section 1518. The long sections 1512, 1516 extend substantially parallel to the side frame portion 1500 towards each other, and the short sections 1514, 1518 extend at a (e.g., normal) angle to the side frame portion 1500 such that they are in contact with the side frame portion 1500. Similarly, there may be two L-shaped conductive elements near (e.g., above or under) the track 1510, with one comprising a long section 1520 and a short section 1522 and the other comprising a long section 1524 and a short section 1526. The long sections 1520, 1524 extend substantially parallel to the side frame portion 1502 towards each other, and the short sections 1522, 1526 extend at a (e.g., normal) angle to the side frame portion 1502 such that they are in contact with the side frame portion 1502.

[0063] FIGs 16A-16C show beam patterns for different cases, namely: FIG. 16A shows the beam patterns with (dashed line) and without (solid line) the coupling structure used in the dual-band antenna according to the sixth exemplary embodiment at a low frequency of 1.95 GHz, FIG. 16B shows the beam patterns for the dual-band antenna according to the sixth exemplary embodiment without the coupling structure at three higher frequencies (i.e., 3.5 GHz, 3.55 GHz and 3.6 GHz), and FIG. 16C shows the beam patterns for the dual-band antenna according to the sixth exemplary embodiment with the coupling structure at the same higher frequencies. One can clearly see that the use of the coupling structure shown in FIGs 15A-15C provides an increase in the antenna beam width at higher frequencies. Although the exemplary embodiments of the present disclosure are described herein, it should be noted that any various changes and modifications could be made in the embodiments of the present disclosure, without departing from the scope of legal protection which is defined by the appended claims. In the appended claims, the word “comprising” does not exclude other elements or operations, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

CLAIMS1. A wireless communication device comprising: a grounding plate; a printed circuit board, PCB, arranged on the grounding plate, the PCB comprising a wireless communication module; a conductive frame extending along edges of the grounding plate, the conductive frame comprising a first frame portion and a second frame portion separated from the first frame portion; and a feeding structure configured to feed the first frame portion of the conductive frame with a feeding signal, the feeding structure comprising: a conductive strip spaced from and extending substantially parallel to the first frame portion of the conductive frame, the conductive strip being connected to the wireless communication module; a first conductive element spaced from the conductive strip, the first conductive element having an L-shaped profile comprising a long section and a short section; and a second conductive element spaced from each of the conductive strip and the first conductive element, the second conductive element having an L-shaped profile comprising a long section and a short section; wherein the long sections of the first conductive element and the second conductive element extend substantially parallel to the first frame portion of the conductive frame towards each other, and wherein the short sections of the first conductive element and the second conductive element extend at an angle to the first frame portion of the conductive frame such that the first conductive element and the second conductive element are in contact with the first frame portion of the conductive frame.

2. The device of claim 1 , wherein the long sections of the first conductive element and the second conductive element are aligned with each other.

3. The device of claim 1, wherein the long sections of the first conductive element and the second conductive element partly overlap each other.

4. The device of any one of claims 1 to 3, wherein the conductive strip, the first conductive element and the second conductive element are spaced from the first frame portion and from each other by a dielectric material.

5. The device of any one of claims 1 to 4, wherein the conductive frame further comprises a third frame portion separated from each of the first frame portion and the second frame portion, the third frame portion being arranged opposite to the second frame portion, each of the third frame portion and the second frame portion having a phase center spaced from a phase center of the first frame portion at a distance equal to a half- wavelength of an electromagnetic wave to be radiated by the first frame portion.

6. The device of any one of claims 1 to 4, wherein the conductive frame further comprises a third frame portion separated from each of the first frame portion and the second frame portion, the third frame portion being arranged opposite to the second frame portion, each of the third frame portion and the second frame portion having a phase center spaced from a phase center of the first frame portion at a distance other than a half- wavelength of an electromagnetic wave to be radiated by the first frame portion, and wherein the device further comprises a coupling structure configured to couple a part of the feeding signal to each of the second frame portion and the third frame portion so as to cause the second frame portion and the third frame portion to radiate electromagnetic waves having a phase difference of 180 degrees and an equal amplitude.

7. The device of claim 6, wherein the coupling structure comprises: a first sub-structure comprising a first conductive track and a second conductive track connected to the first conductive track, the first conductive track extending substantially parallel to the first frame portion, the second conductive track extending substantially parallel to the second frame portion; and a second sub-structure comprising a third conductive track and a fourth conductive track connected to the third conductive track, the third conductive track extending substantially parallel to the first frame portion and being spaced from the first conductive track, the fourth conductive track extending substantially parallel to the third frame portion.

8. The device of claim 7, wherein the coupling structure further comprises: a third conductive element; a fourth conductive element; a fifth conductive element; and a sixth conductive element; wherein the third to sixth conductive elements are spaced from each other, and each of the third to sixth conductive elements has an L-shaped profile comprising a long section and a short section; wherein the long sections of the third conductive element and the fourth conductive element extend substantially parallel to the second frame portion towards each other, and the short sections of the third conductive element and the fourth conductive element extend at an angle to the second frame portion such that the third conductive element and the fourth conductive element are in contact with the second frame portion; and wherein the long sections of the fifth conductive element and the sixth conductive element extend substantially parallel to the third frame portion towards each other, and the short sections of the fifth conductive element and the sixth conductive element extend at an angle to the third frame portion such that the fifth conductive element and the sixth conductive element are in contact with the third frame portion.

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