BACKGROUND OF THE INVENTION
1. Field of the Invention
The subject application generally relates to a mobile device, and more particularly, relates to a mobile device for improving isolation between a plurality of antennas in an antenna array. The speed at which the mobile device transmits high-resolution audio/video data to other display device interfaces is also improved.
2. Description of the Related Art
With the progress of mobile communication technology, a camera or video recorder in a mobile device can retrieve high-resolution images and videos. Some high-end mobile devices use HDMI (High-Definition Multimedia Interface) cables as an interface to transmit high-resolution audio/video data to other display devices. However, it is more convenient for people to use wireless transmission, in particular to a 60 GHz band which has sufficient bandwidth for transmitting high-quality video data.
Traditionally, an antenna array for transmitting data usually occupies a lot of space in a mobile device. Furthermore, mutual coupling between a plurality of antennas is serious, and the transmission speed is bad. This decreases communication quality of the mobile device.
BRIEF SUMMARY OF THE INVENTION
In one exemplary embodiment, the subject application is directed to a mobile device, at least comprising: a dielectric substrate; an antenna array, comprising: a first antenna; a second antenna; and a third antenna, positioned between the first antenna and the second antenna so as to reduce coupling between the first antenna and the second antenna, wherein the first antenna, the second antenna and the third antenna are embedded in the dielectric substrate, and are substantially arranged in a straight line; and wherein each of the first antenna and the second antenna is a transmission antenna and the third antenna is a reception antenna, or each of the first antenna and the second antenna is the reception antenna and the third antenna is the transmission antenna; and a transceiver, coupled to the antenna array, and configured to transmit or receive a signal.
BRIEF DESCRIPTION OF DRAWINGS
The subject application can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:
FIG. 1A is a pictorial drawing for illustrating a mobile device according to an embodiment of the invention;
FIG. 1B is a pictorial drawing for illustrating a mobile device according to another embodiment of the invention;
FIG. 2 is a diagram for illustrating an antenna array according to an embodiment of the invention;
FIG. 3A is a pictorial drawing for illustrating a slot antenna according to an embodiment of the invention;
FIG. 3B is a vertical view for illustrating the slot antenna according to the embodiment of the invention;
FIG. 4 is a diagram for illustrating return loss of the slot antenna according to an embodiment of the invention;
FIG. 5A is a pictorial drawing for illustrating a monopole antenna according to an embodiment of the invention;
FIG. 5B is a vertical view for illustrating the monopole antenna according to the embodiment of the invention;
FIG. 6 is a diagram for illustrating return loss of the monopole antenna according to an embodiment of the invention;
FIG. 7 is a pictorial drawing for illustrating a mobile device according to an embodiment of the invention; and
FIG. 8 is a pictorial drawing for illustrating a mobile device according to another embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1A is a pictorial drawing for illustrating a mobile device 100 according to an embodiment of the invention. The mobile device may be a smart phone, a tablet, or a notebook. As shown in FIG. 1A, the mobile device at least comprises a dielectric substrate 110, an antenna array 130, and a transceiver 170. A skilled person in the art can comprehend that the mobile device 100 may further comprise a processor, a display module, a touch module, an input module, and other electronic components even if they are not shown in FIG. 1A. In some embodiments, the dielectric substrate 110 is an FR4 substrate or an LTCC (Low Temperature Co-fired Ceramics) substrate, and the transceiver 170 is a TR (Transmission and Reception) chip disposed on the dielectric substrate 110. The transceiver 170 is electrically coupled to the antenna array 130, and is configured to transmit or receive a signal.
The antenna array 130 is close to a lateral edge 112 of the dielectric substrate 110 so as to generate end-fire radiation, for example, substantially toward an X-direction in FIG. 1A. In an embodiment, the transceiver 170 is configured to adjust a main beam of the antenna array 130 toward a specific direction, which may be a reception direction of other display device interfaces (e.g., a monitor, a television, a projector, or a mobile device). The antenna array 130 comprises one or more transmission antennas AT for transmitting signals and one or more reception antennas AR for receiving signals. Since the transmission antennas AT are interleaved with the reception antennas AR, the isolation between the transmission antennas AT and/or the isolation between the reception antennas AR can be improved. In addition, all of the transmission antennas AT and the reception antennas AR of the antenna array 130 are embedded in the dielectric substrate 110, and the surface of the dielectric substrate 110 has sufficient space to accommodate other components, such as a TR chip. In an embodiment, the reception antennas AR and/or the transmission antennas AT are slot antennas, monopole antennas, dipole antennas, or Yagi antennas.
FIG. 1B is a pictorial drawing for illustrating a mobile device 190 according to another embodiment of the invention. As shown in FIG. 1B, the mobile device 190 further comprises another antenna array 150 close to another lateral edge 114 of the dielectric substrate 110 so as to generate end-fire radiation, wherein the lateral edge 114 is substantially perpendicular to the lateral edge 112. In the embodiment, the main beam of the antenna array 130 is substantially toward the X-direction, and the main beam of the antenna array 150 is substantially toward a Y-direction. Similarly, the transceiver 170 is configured to dynamically adjust the main beams of the antenna arrays 130 and 150 toward a specific direction parallel to a reception direction of another display device interface.
FIG. 2 is a diagram for illustrating the antenna array 130 (or 150) according to an embodiment of the invention. As shown in FIG. 2, the antenna array 130 (or 150) comprises at least three antennas 131, 132 and 133. The antenna 133 is positioned between the antennas 131 and 132 so as to reduce coupling between the antennas 131 and 132. Note that the two adjacent antennas should be of different types to improve isolation. In an embodiment, each of the antennas 131 and 132 is a transmission antenna AT, and the antenna 133 is a reception antenna AR. In another embodiment, each of the antennas 131 and 132 is a reception antenna AR, and the antenna 133 is a transmission antenna AT. Note that since the antennas 131 and 132 are of the same type, a synthetic beam is formed by switching and adjusting the transceiver 170, and further by altering input phase and input energy of the antenna 131 and 132 so as to dynamically adjust the main beams of the antenna arrays 130 and 150. Therefore, other display device interfaces can have the optimal transmission and reception quality to increase the efficiency of wireless transmission. In a preferred embodiment, the antennas 131, 132 and 133 are all embedded in the dielectric substrate 110 and are substantially arranged in a straight line. The distance D12 between the antennas 131 and 132 is approximately half wavelength (an) of a central operating frequency of the antenna array 130. In another embodiment, the distance D13 between the antennas 131 and 133 is approximately equal to the distance D23 between the antennas 132 and 133. The antenna array 130 (or 150) may comprise more transmission antennas AT and more reception antennas AR as shown in FIG. 1A.
FIG. 3A is a pictorial drawing for illustrating a slot antenna 300 according to an embodiment of the invention. FIG. 3B is a vertical view for illustrating the slot antenna 300 according to the embodiment of the invention. In a preferred embodiment, each reception antenna AR in the antenna array 130 (or 150) is a slot antenna 300 embedded in the dielectric substrate 110. As shown in FIGS. 3A and 3B, the slot antenna 300 comprises a ground structure 310, a feeding element 320, and a cavity structure 350. The ground structure 310, the feeding element 320 and the cavity structure 350 are all made of metal, such as aluminum or copper. The ground structure 310 is substantially flat and has a slot 315, which is parallel to the ground structure 310. The feeding element 320 is electrically coupled to a signal source 390 and extends across the slot 315 of the ground structure 310 such that the slot antenna 300 is excited. The cavity structure 350 is substantially a hollow metal housing and is electrically coupled to the ground structure 310. An open side 351 of the cavity structure 350 faces the slot 315 of the ground structure 310. The cavity structure 350 is configured to reflect electromagnetic waves to enhance the gain of the slot antenna 300. In other embodiments, the cavity structure 350 is removed from the slot antenna 300. In a preferred embodiment, the dielectric substrate 110 is an LTCC substrate which comprises a plurality of metal layers ML and a plurality of vias VA, and the ground structure 310 and the cavity structure 350 are formed by some of the plurality of metal layers ML and some of the plurality of vias VA. The plurality of vias are electrically coupled between the plurality of metal layers ML. In order to avoid leakage waves, the distance between any two adjacent vias VA should be smaller than 0.125 wavelength (λ/8) of a central operating frequency of the antenna array 130. The feeding element 320 may further extend through a circular hole MLH in the top metal layer ML into an interior of the cavity structure 350. In an embodiment, the feeding element 320 comprises a microstrip line or a stripline.
FIG. 4 is a diagram for illustrating return loss of the slot antenna 300 according to an embodiment of the invention. The vertical axis represents return loss (unit: dB), and the horizontal axis represents operating frequency (unit: GHz). As shown in FIG. 4, the slot antenna 300 is excited to form a frequency band FB1 which is approximately from 57 GHz to 66 GHz. Therefore, the slot antenna 300 is capable of covering the 60 GHz band.
FIG. 5A is a pictorial drawing for illustrating a monopole antenna 500 according to an embodiment of the invention. FIG. 5B is a vertical view for illustrating the monopole antenna 500 according to the embodiment of the invention. In a preferred embodiment, each transmission antenna AT in the antenna array 130 (or 150) is a monopole antenna 500 embedded in the dielectric substrate 110, and extends in a direction perpendicular to the dielectric substrate 110 (e.g., the X-direction). As shown in FIGS. 5A and 5B, the monopole antenna 500 comprises a ground structure 510, a main radiation element 520, a feeding element 530, and a reflection structure 550 that are all made of metal, such as aluminum or copper. The ground structure 510 is substantially flat and has a small hole 515. One end 525 of the main radiation element 520 extends through the small hole 515 of the ground structure 510 perpendicularly. In an embodiment, the main radiation element 520 comprises two radiation sub-elements, an I-shaped radiation sub-element 521 and a J-shaped radiation sub-element 522. The I-shaped radiation sub-element 521 extends through the small hole 515 of the ground structure 510, and the J-shaped radiation sub-element 522 is electrically coupled to one end of the I-shaped radiation sub-element 521. In other embodiments, the main radiation element 520 has other shapes, such as an I-shape, a C-shape, or a Z-shape. The feeding element 530 is electrically coupled to the end 525 of the main radiation element 520, and is further electrically coupled to a signal source 590. In an embodiment, the feeding element 530 comprises a rectangular coaxial cable which is substantially parallel to the ground structure 510 and substantially perpendicular to the main radiation element 520. The reflection structure 550 is substantially flat. The reflection structure 550 is electrically coupled to the ground structure 510 and substantially perpendicular to the ground structure 510. The reflection structure 550 is close to the main radiation element 520 so as to reflect electromagnetic waves and adjust the radiation pattern of the monopole antenna 500. In other embodiments, the reflection 550 is removed from the monopole antenna 500. Similarly, in a preferred embodiment, the dielectric substrate 110 is an LTCC substrate which comprises a plurality of metal layers and a plurality of vias. Although not shown in FIGS. 5A and 5B, the ground structure 510 and the reflection 550 may be formed by some of the plurality of metal layers and some of the plurality of vias. Note that if the slot antenna 300 is adjacent to the monopole antenna 500, the ground structure 310 in FIG. 3A is electrically coupled to the ground structure 510 in FIG. 5A.
FIG. 6 is a diagram for illustrating return loss of the monopole antenna 500 according to an embodiment of the invention. The vertical axis represents return loss (unit: dB), and the horizontal axis represents operating frequency (unit: GHz). As shown in FIG. 6, the monopole antenna 500 is excited to form a frequency band FB2 which is approximately from 57 GHz to 66 GHz. Therefore, the monopole antenna 500 is capable of covering the 60 GHz band. According to FIGS. 4 and 6, the antenna array 130 (or 150) is capable of covering an array band which is approximately from 57 GHz to 66 GHz.
FIG. 7 is a pictorial drawing for illustrating a mobile device 700 according to an embodiment of the invention. As shown in FIG. 7, a transceiver 170 of the mobile device 700 comprises a TR (Transmission and Reception) switch 172 and a tuner 174. The TR switch 172 is configured to exchange the functions of the transmission antenna AT and the reception antenna AR. In other words, the transmission antenna AT can receive signals, and the reception antenna AR can transmit signals. The tuner 174 is configured to dynamically adjust the main beam of the antenna array 130 toward a specific direction (e.g., toward a reception direction of other display device interfaces). The TR switch 172 and the tuner 174 may be a portion of circuits in a TR chip. In other embodiments, the TR switch 172 is independent of the transceiver 170.
FIG. 8 is a pictorial drawing for illustrating a mobile device 800 according to another embodiment of the invention. As shown in FIG. 8, the mobile device 800 further comprises another antenna array 820 which is disposed on a surface of the dielectric substrate 110 and is electrically coupled to the transceiver 170. In the embodiment, the main beam of the antenna array 130 is substantially toward the X-direction, and a main beam of the antenna array 820 is substantially toward a Z-direction perpendicular to the X-direction. Similarly, the antenna array 820 may comprise one or more transmission antennas or reception antennas, such as patch antennas.
As to element parameters, in an embodiment, the dielectric substrate 110 is an LTCC substrate. The dielectric substrate 110 has a thickness of about 1.45 mm and has a dielectric constant of about 7.5. The foregoing parameters can be adjusted according to desired frequency bands.
The mobile device and the antenna array of the subject application therein have the following advantages: (1) The antenna array is embedded in the dielectric substrate such that design space is saved; (2) The transmission antennas are interleaved with the reception antennas in the antenna array to reduce mutual coupling and to decrease the total length of the antenna array; (3) The antenna array is close to a lateral edge of the dielectric substrate to generate end-fire radiation in a horizontal direction; and (4) The main beam of the antenna array is easily tunable.
The embodiments of the disclosure are considered as exemplary only, not limitations. It will be apparent to those skilled in the art that various modifications and variations can be made on the invention. The true scope of the disclosed embodiments is indicated by the following claims and their equivalents.
Patent Application
20130257668
