TWI530020B - Antenna system - Google Patents

Description

Antenna system

The present invention relates to an antenna system, and more particularly to an antenna system that covers different polarization directions and is operable in multiple frequency bands and has a small size.

With the rapid development of wireless communication technology, today's electronic products such as notebook computers, Personal Digital Assistants, wireless base stations, mobile phones, smart meters, USB dongles Most of them have wireless communication capabilities that enable technologies such as wireless local area networks (WiFi) to replace data transmission via cable. Wireless communication technology transmits or receives radio waves through an antenna to transmit or exchange radio signals to access a wireless network. In general, wireless local area network communication systems can operate in multiple frequency bands, so how to develop antennas that can operate in multiple frequency bands has also become a trend of current research. In addition, the size of the antenna needs to be developed in the direction of miniaturization to match the trend of shrinking the size of electronic products, while still ensuring the isolation and radiation pattern of the antenna.

Therefore, how to design an antenna that can operate in multiple frequency bands in a limited space, while taking into account the efficiency and production cost of the antenna, has become one of the goals of the industry.

The present invention primarily provides an antenna system operable in a plurality of frequency bands that can cover different polarization directions and occupy a small volume.

The present invention discloses an antenna system including a first antenna unit, including a first An antenna element and a second antenna element, wherein the first antenna element and the second antenna element are disposed on a first plane for transmitting and receiving a first frequency band signal and a second frequency band signal; a second antenna unit includes a third antenna element and a fourth antenna element, wherein the third antenna element and the fourth antenna element are disposed on a second plane for transmitting and receiving a third frequency band signal and a fourth frequency band signal; wherein the first plane is substantially perpendicular to the second plane.

10‧‧‧Antenna system

AU1, AU2, AU3‧‧‧ antenna unit

AE1_1, AE1_2, AE2_1, AE2_2, AE3_1, AE3_2, AE4_2‧‧‧ antenna elements

SUB1, SUB2, SUB3‧‧‧ substrate

110, 120, 130, 140, 210, 220, 230, 240, 310, 320, 330, 340, 420, 430, 520, 530, 630, 640 ‧ ‧ radiator

111, 121, 131, 141, 211, 221, 231, 241, 311, 321, 331, 341 ‧ ‧ feed points

122, 132‧‧‧ openings

D1, D2, D3, D4‧‧‧ spacing

D‧‧‧Distance

L1, L2‧‧‧ length

CL_1, CL_2‧‧‧ central axis

FIG. 1 is a schematic diagram of an antenna system according to an embodiment of the present invention.

Figure 2 is a schematic diagram of an antenna unit.

Figure 3 is a schematic diagram of an antenna unit.

Figure 4 is a schematic diagram of an antenna unit.

Fig. 5 is a view showing the actual measurement result of the antenna isolation of the antenna element shown in Fig. 2.

Fig. 6 and Fig. 7 are diagrams showing the simulated radiation 2D field pattern of the antenna unit shown in Fig. 2 operating at 2.45 GHz and 5.5 GHz, respectively.

Fig. 8 is a view showing the antenna reflection coefficient of the antenna element shown in Fig. 2.

Fig. 9 and Fig. 10 are diagrams showing the actual measured radiation 3D field pattern of the antenna unit shown in Fig. 1 operating at 2.4 GHz and 5 GHz, respectively.

Figure 11 is a schematic view of a radiator of an embodiment of the present invention.

Figure 12 is a schematic view of a radiator of an embodiment of the present invention.

Figure 13 is a schematic diagram of an antenna element according to an embodiment of the present invention.

Please refer to FIG. 1. FIG. 1 is a schematic diagram of an antenna system 10 according to an embodiment of the present invention. The antenna system 10 includes antenna elements AU1, AU2, AU3. The antenna unit AU1 includes antenna elements AE1_1 and AE1_2, and the antenna elements AE1_1 and AE1_2 are disposed on a substrate SUB1 to be coplanar (ie, yz plane) and orthogonal to each other. The antenna unit AU2 includes antenna elements AE2_1 and AE2_2, The antenna elements AE2_1 and AE2_2 are disposed on a substrate SUB2 to be coplanar (ie, xy plane) and orthogonal to each other. The antenna unit AU3 includes antenna elements AE3_1 and AE3_2, and the antenna elements AE3_1 and AE3_2 are disposed on a substrate SUB3 to be coplanar (ie, xz plane) and orthogonal to each other. The antenna elements AE1_1, AE2_1, and AE3_1 can transmit and receive signals of the same frequency band (such as 5 GHz), and the antenna elements AE1_2, AE2_2, and AE3_2 can transmit and receive signals of the same frequency band (such as 2.4 GHz) to cover different polarization directions for a specific frequency band. Signal. In other words, the antenna elements (such as the antenna elements AE1_1 and AE1_2) included in the same antenna unit are used to transmit and receive signals of different frequency bands, and all antenna units AU1, AU2, and AU3 can transmit and receive signals of two frequency bands, but the present invention does not Limited. In addition, since the antenna elements AE1_1 and AE1_2 are both disposed on the substrate SUB1, the process steps of the antenna elements AE1_1 and AE1_2 can be simplified, and since the antenna elements AE2_1 and AE2_2 are also disposed on the substrate SUB2, and the antenna elements AE3_1 and AE3_2 are also It is disposed on the substrate SUB3, so the assembly step can be further simplified.

It should be noted that the antenna elements included in each antenna unit are orthogonal to each other, and the polarization directions of the antenna elements are orthogonal to each other by appropriately setting the relative relationship of the antenna elements. Since the antenna elements on the same substrate are orthogonal to each other, it is ensured that the isolation between the antenna elements is in accordance with the wireless transmission requirement, and the antenna elements can be closely arranged to reduce the area of the antenna unit. In addition, the substrates are perpendicular to each other, so interference between antenna elements on different substrates can be reduced to further minimize the volume of the antenna system 10.

In detail, please refer to FIG. 2 to FIG. 4, FIG. 2 is a schematic diagram of the antenna unit AU1, FIG. 3 is a schematic diagram of the antenna unit AU2, and FIG. 4 is a schematic diagram of the antenna unit AU3. Since the operation modes of the antenna elements AU1, AU2, and AU3 are similar, the antenna unit AU1 will be mainly described below for the sake of brevity. First, as shown in Fig. 2, the antenna elements AE1_1, AE1_2 of the antenna unit AU1 respectively include radiators 110, 120, 130, 140 and feed points 111, 121, 131, 141 to form a dipole antenna. The relatively disposed radiators 110 and 120, 130 and 140 are used for transmitting and receiving wireless signals, and can reduce the required area by bending. For example, after the radiator 110 is straightened and straightened with the radiator 120, the total length is approximately 0.5 times the wavelength of the signal to be transmitted and received (such as the signal of the 5 GHz band). After bending, the ends of the radiators 110 and 120 are bent. The length L1 between them is approximately 0.37 times the wavelength, so it can be placed in a narrow space of 22×10 mm ² . Similarly, the length L2 between the ends of the radiators 130 and 140 after bending is roughly required for transmission and reception. The signal (such as the signal in the 2.4 GHz band) is 0.3 times the wavelength, so it can be placed in a small space of 38 × 13 mm ² to help reduce the overall volume. However, bending the radiators 110, 120, 130, 140 of the dipole antenna will lose the antenna gain. Therefore, the radiators 110 and 120 respectively have a double-branched U-shaped structure, and the radiators 130 and 140 are respectively bi-branched. Bend the structure to increase the current path and compensate for the antenna gain loss caused by the bend. The double branch of the radiator 120 extends in the (+y) direction (y-directed or oriented in the y direction), that is, the feed point 121 on the radiator 120 forms an opening 122 formed at the bifurcated end of the radiator 120. A vector pointing in the y direction, and the double branches of the radiator 110 extend in the (-y) direction, and the antenna element AE1_1 is polarized along the y axis. On the other hand, the double branches of the radiator 130 of the antenna element AE1_2 extend in the z direction, that is, the feed point 131 on the radiator 130 forms an orientation (+z) direction with the opening 132 formed at the bifurcated end of the radiator 130. The vector, and the double branches of the radiator 140 extend in the (-z) direction, and the antenna element AE1_2 is polarized along the y axis. Obviously, the antenna elements AE11, AE12 are orthogonal to each other.

In other words, the required installation area of the antenna elements AE1_1 and AE1_2 can be reduced by bending the radiators 110, 120, 130, 140, and since the antenna elements AE1_1 and AE1_2 on the same substrate are orthogonal to each other, the antenna element AE1_1 can be closely arranged. And AE1_2 to reduce the overall size of the antenna unit AU1, while the antenna elements AE1_1 and AE1_2 still have good isolation. Please refer to FIG. 5, which is a schematic diagram of the antenna isolation simulation results of the antenna elements AE1_1 and AE1_2 shown in FIG. As shown in Fig. 5, in the frequency bands of 5.15 GHz to 5.82 GHz and 2.41 GHz to 2.47 GHz, the isolation of the antenna elements AE1_1 and AE1_2 is greater than 15 dB. In addition, Fig. 6 and Fig. 7 are diagrams showing the simulated radiation 2D field pattern of the antenna unit AU1 shown in Fig. 2 operating at 2.45 GHz and 5.5 GHz, respectively. Wherein, since the structures of the antenna elements AE1_1 and AE1_2 are symmetrical and orthogonal to each other, an omni-directional radiation field can be formed on the xy plane when the operating frequency is 2.45 GHz, when the operating frequency is At 5.5 GHz, an omnidirectional radiation pattern can be formed on the xz plane. Similarly, as shown in FIGS. 3 and 4, the antenna element AE2_1 is polarized in the x direction, the antenna element AE2_2 is polarized in the y direction, and the antenna elements AE2_1 and AE2_2 are orthogonal to each other; the antenna element AE3_1 is along the z direction. The antenna element AE3_2 is polarized in the x direction, and the antenna elements AE3_1, AE3_2 are orthogonal to each other. Accordingly, the antenna elements of the antenna elements AU2, AU3 also have good isolation and radiation pattern.

In addition, as shown in FIG. 2, the radiators 110 and 120 (or the feed points 111 and 121) of the antenna element AE1_1 are separated by a distance D1 which affects the parasitic capacitance between the radiators 110 and 120. Similarly, the radiators 130 and 140 (or the feed points 131 and 141) of the antenna element AE1_2 are separated by a distance D2, which may affect the parasitic capacitance between the radiators 130 and 140. Therefore, by appropriately adjusting the pitches D1, D2, the impedance characteristics of the antenna elements AE1_1, AE1_2 can be individually changed to improve the radiation efficiency. Please refer to FIG. 8. FIG. 8 is a schematic diagram showing the antenna reflection coefficients of the antenna elements AE1_1 and AE1_2 shown in FIG. The dotted line represents the simulation result of the reflection coefficient of the antenna element AE1_1, and the solid line represents the simulation result of the reflection coefficient of the antenna element AE1_2. It can be seen from FIG. 8 that by adjusting the pitches D1 and D2 to an appropriate size, the reflection loss (Return Loss) of the antenna element AE1_1 in the frequency band of 4.00 GHz to 6.50 GHz and the antenna element AE1_1 in the frequency band of 2.17 GHz to 2.84 GHz are known. Both are less than -10dB, meaning that 90% of the energy can be transmitted, so that better radiation efficiency can be obtained. In other words, the antenna elements AE1_1, AE1_2 of the present invention do not need to increase the π-type matching circuit to improve the impedance matching problem as in the prior art, but ensure the impedance matching by the pattern design of the antenna elements AE1_1, AE1_2 and the adjustment intervals D1, D2. And improve the radiation efficiency.

Further, as shown in FIG. 1 , since the yz plane where the antenna elements AE1_1 and AE1_2 are located, the xy plane where the antenna elements AE2_1 and AE2_2 are located, and the xz plane where the antenna elements AE3_1 and AE3_2 are located are perpendicular to each other, The interference between the antenna elements on different substrates is further reduced and the volume of the antenna system 10 is reduced. The polarization (ie, the x direction) of the antenna element AE2_1 of the antenna unit AU2 is orthogonal to the polarization (ie, the y, z direction) of the antenna elements AE1_1 and AE1_2 of the antenna unit AU1 adjacent thereto, and the antenna of the antenna unit AU2 The polarization of the element AE2_2 (ie, the y direction) is orthogonal to the polarization of the antenna element AE3_2 of the adjacent antenna unit AU3 (ie, the x direction), but the invention is not limited thereto, and may be other arrangements. The antenna elements AU1, AU2, AU3 are combined. In addition, FIG. 9 and FIG. 10 are actual measured 3D radiation pattern diagrams of the antenna elements AU1, AU2, and AU3 shown in FIG. 1 operating at 2.4 GHz and 5 GHz, respectively. As shown in Figures 9 and 10, the antenna elements AU1, AU2, AU3 may cover different polarization directions.

It should be noted that the antenna system 10 is an embodiment of the present invention, and those skilled in the art can make different changes. For example, the antenna elements AE1_1, AE2_1, and AE3_1 of the present invention are in reflection symmetry, and the antenna elements AE1_2, AE2_2, and AE3_2 are rotationally symmetrical, meaning that the antenna elements AE1_2, AE2_2, and AE3_2 are opposite to the center thereof. The point can be completely overlapped after the point is rotated by 180°, but the antenna element can also be designed as an asymmetrical structure according to the actual design requirements. In addition, the pattern and type of the antenna element are not limited thereto, and may be other antenna structures, and the size of the radiator may be adaptively adjusted according to the requirements of the operating frequency. The substrate can be a fiberglass board conforming to the specifications of an FR4 sheet, and other medium substrates can be used according to requirements.

In addition, the central axis CL_1 of the antenna element AE1_1 passes through the feeding points 111, 121, and the central axis CL_2 of the antenna element AE1_2 passes through the feeding points 131, 141, wherein the central axis CL_1 of the antenna element AE1_1 is separated from the central axis CL_2 of the AE1_2 Distance D, distance D and feed point 111, The polarity of 121 and feed points 131, 141 can be appropriately adjusted according to different system requirements to optimize the performance of antenna elements AE1_1 and AE1_2 for different design considerations. In addition, the feed points 111 and 121 are respectively connected to a center conductor and an outer ground conductor (not shown) of a coaxial transmission line for inputting signals received by the radiators 110 and 120 to a back-end processing circuit (not shown). Or providing signals to the radiators 110, 120; the feed points 131, 141 are respectively connected to the center conductor and the outer ground conductor of the other coaxial transmission line for inputting the signals received by the radiators 130, 140 to the back end processing circuit, or Signals are provided to the radiators 130, 140. In other words, for the antenna elements AE1_1 and AE1_2 for transmitting and receiving signals of different frequency bands, the feeding points 111, 121 and the feeding points 131, 141 can form the dual-input dual-frequency antenna structure of the antenna elements AE1_1 and AE1_2 to avoid the conventional dual-frequency antenna. Since there is only a single feed, it is necessary to additionally add a switching circuit or a duplexer circuit to the circuit to separate the signals of different frequency bands. Accordingly, the dual-input dual-frequency antenna structure of the present invention can reduce the cost, and can avoid the switching circuit or the duplexer circuit from affecting the antenna characteristics, and can further ensure the bandwidth, gain, and radiation efficiency.

In addition, the number of segments in which the radiator is bent is also not limited. The radiator 110 shown in FIG. 2 includes three segments, and the radiator 130 includes 15 segments, but may be appropriately adjusted to increase or decrease. The number of segments, or further reduce the overall area of the antenna element. Further, the segments of the antenna elements may have different widths. For example, the feed points 131, 141 shown in Fig. 2 are respectively disposed on the wider segments of the radiator 130 and the radiator 140. Furthermore, as shown in FIG. 2, the angle of the segment is 90 degrees, but is not limited thereto, and may be any value between 90 degrees and 180 degrees. In addition, FIG. 11 is a schematic view of a radiator 420, 430 according to an embodiment of the present invention. The radiator 420 can replace the radiators 110, 120 in Fig. 2, and the radiator 430 can replace the radiators 130, 140 in Fig. 2. Among them, the side turn of the segment can form all oblique angles to reduce the influence of the discontinuous surface and reduce the parasitic capacitance effect. Figure 12 is a schematic view of a radiator 520, 530 according to an embodiment of the present invention. The radiator 520 can replace the radiators 110, 120 in Fig. 2, and the radiator 530 can replace the radiators 130, 140 in Fig. 2, wherein the radiators 520, 530 can have a curved profile. In addition, FIG. 13 is a schematic diagram of an antenna element AE4_2 according to an embodiment of the present invention. Antenna element AE4_2 can replace the first The antenna elements AE1_2, AE2_2, AE3_2 in the figure. Wherein, the spacing between the radiators 630, 640 of the antenna element AE4_2 is changed from D3 to D4, and then from D4 to D3, instead of a certain value, so the geometry of the parasitic capacitance can be changed.

In summary, the substrate of the present invention is provided with a plurality of antenna elements of the antenna unit, thereby simplifying the process and assembly steps. Moreover, the antenna elements of the antenna unit are orthogonal to each other, so that the isolation between the antenna elements can be ensured to meet the wireless transmission requirements, and the area of the antenna unit can be minimized. In addition, since the substrates are perpendicular to each other, interference between the antenna elements can be reduced to further reduce the volume of the antenna system. Corresponding to the configuration of the antenna elements, the present invention appropriately designs the pattern of the antenna elements to reduce the overall area of the antenna elements while ensuring antenna gain and impedance matching to improve radiation efficiency.

The above are only the preferred embodiments of the present invention, and all changes and modifications made to the scope of the present invention should be within the scope of the present invention.

10‧‧‧Antenna system

AU1, AU2, AU3‧‧‧ antenna unit

AE1_1, AE1_2, AE2_1, AE2_2, AE3_1, AE3_2, AE4_2‧‧‧ antenna elements

SUB1, SUB2, SUB3‧‧‧ substrate

Claims (8)

An antenna system includes: a first antenna unit, including a first antenna element and a second antenna element, wherein the first antenna element and the second antenna element are disposed on a first plane For transmitting and receiving a first frequency band signal and a second frequency band signal, and a second antenna unit, comprising a third antenna element and a fourth antenna element, wherein the third antenna element and the fourth antenna The component is disposed on a second plane for transmitting and receiving a third frequency band signal and a fourth frequency band signal; wherein the first plane is substantially perpendicular to the second plane, and the first frequency band signal is located at the third frequency band signal a first frequency band, the second frequency band signal and the fourth frequency band signal are located in a second frequency band, the first frequency band is different from the second frequency band, and the first antenna element, the second antenna element, the The third antenna element and the fourth antenna element are both dipole antennas. The antenna system of claim 1, wherein a first polarization direction of the first antenna element and a second polarization direction of the second antenna element are orthogonal to each other, and one of the third antenna elements The third polarization direction and one of the fourth antenna elements and the fourth polarization direction are orthogonal to each other. The antenna system of claim 1, further comprising a third antenna unit, comprising a fifth antenna element and a sixth antenna element, wherein the fifth antenna element and the sixth antenna element are disposed on a third plane And respectively for transmitting and receiving a fifth frequency band signal and a sixth frequency band signal, wherein the third plane is substantially perpendicular to the first plane and the second plane. The antenna system of claim 2, wherein the first antenna element comprises: a first radiator, substantially a U-shaped double-branched structure; and a second radiator having substantially the U-shaped double-branched structure. Wherein the first antenna element is in reflection symmetry, and the first radiator is separated from the second radiator a first pitch to form a parasitic capacitance; a first feed point disposed on the first radiator; and a second feed point disposed on the second radiator. The antenna system of claim 4, wherein the first radiator extends in the first polarization direction, and the second radiator extends in a direction opposite to the first polarization direction. The antenna system of claim 2, wherein the second antenna element comprises: a third radiator comprising a plurality of segments to form a bent double-branched structure; and a fourth radiator comprising a plurality of segments to form the bent double-branched structure, wherein the second antenna element is in a rotational symmetry, and a parasitic capacitance is formed between the third radiator and the fourth radiator; a third feed point disposed on the third radiator; and a fourth feed point disposed on the fourth radiator. The antenna system of claim 6, wherein the plurality of segments of the third radiator comprise a first segment and a second segment, the plurality of segments of the fourth radiator comprising a third a segment and a fourth segment, the first segment being parallel to the adjacent third segment and having a first spacing, the second segment being parallel to the adjacent fourth segment and having a first segment Two pitches, the first pitch being not equal to the second pitch. The antenna system of claim 6, wherein the third radiator extends in the second polarization direction, and the fourth radiator extends in a direction opposite to the second polarization direction.