Patent Application
20160302081
1. Field of the Invention
The present invention relates to a smart antenna module and omni-directional antenna thereof, and more particularly, to a smart antenna module and omni-directional antenna thereof having a radiation pattern which is adjusted by adjusting the ground state of at least one reflecting unit.
2. Description of the Prior Art
As the growth of number of wireless communication users, the co-channel fading, which degrades the transmission quality and limits the frequency efficiency, increases significantly. Traditionally, one resolution to overcome this problem is the incorporation of the smart antenna. In general, a smart antenna may refer to an adaptive antenna or a switched-beam antenna.
An adaptive antenna aims to reject the interference signals automatically by modifying its radiation pattern. However, it requires a complex RF circuit to synthesize the antenna steering beam. The other solution, i.e. the switched-beam antenna, only requires a set of switches to control the steering beam. Therefore, using the switched-beam antenna is much cost-effective.
The switched-beam antenna supporting WiFi 802.11b/g/n for an access point (AP) had been applied since several years ago. However, with the advance of wireless communication technology, the wireless communication devices may be configured with an increasing number of antennas. For example, a wireless local area network standard IEEE 802.11n supports multi-input multi-output (MIMO) communication technology, i.e. an wireless communication device is capable of concurrently receiving/transmitting wireless signals via multiple(or multiple sets of) antennas, to vastly increase system throughput and transmission distance without increasing system bandwidth or total transmission power expenditure, thereby effectively enhancing spectral efficiency and transmission rate for the wireless communication system, as well as improving communication quality.
As can be seen from the above, a prerequisite for implementing techniques, such as spatial multiplexing, beam forming, spatial diversity, pre-coding, etc., employed in the MIMO communication technology is to employ multiple sets of antenna to divide a space into many channels in order to provide multiple antenna field patterns. Therefore, it is a common goal in the industry to design antennas that suit both transmission demands, as well as dimension and functionality requirements.
It is therefore an objective of the present invention to provide a smart antenna module and omni-directional antenna thereof having a radiation pattern which is adjusted by adjusting the ground state of at least one reflecting unit to carry out beam steering.
An embodiment of the present invention discloses a smart antenna module, including an omni-directional antenna and at least one reflecting unit. The at least one reflecting unit is used for adjusting a radiation pattern of the smart antenna module, wherein each of the at least one reflecting unit includes a reflector and a switch. The switch is coupled between the reflector and a ground of the omni-directional antenna for electrically connecting the reflector with the ground or separating the reflector from the ground according to a control signal to adjust the radiation pattern of the smart antenna module.
Another embodiment of the present invention further discloses an omni-directional antenna including a ground, a feed point and a radiator. The feed point is electrically connected to a wireless signal. The radiator is electrically connected to the feed point for resonating the wireless signal, wherein the radiator includes a first arm electrically connected to the feed point and extending along a first direction from the feed point, a second arm electrically connected to the first arm and extending along a second direction from the first arm, and a third arm electrically connected between the second arm and the ground, wherein the third arm includes a first bend, a first branch electrically connected between the second arm and the first bend and extending along a third direction from the second arm, and a second branch electrically connected between the first bend and the ground and extending along an opposite direction of the first direction from the first bend, a fourth arm electrically connected to the first arm and extending along an opposite direction of the second direction from the first arm, and a fifth arm electrically connected between the fourth arm and the ground, wherein the fifth arm includes a second bend, a third branch electrically connected between the fourth arm and the second bend and extending an opposite direction of the third direction from the fourth arm, and a fourth branch electrically connected between the second bend and the ground and extending along the opposite direction of the first direction from the second bend. The first direction, the second direction and the third direction are perpendicular to each other.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
A smart antenna module of the present invention has two operation modes including an omni-directional mode and a directional mode. When the smart antenna module operates in the omni-directional mode, a radiation pattern of the smart antenna module may be an omni-directional radiation pattern for transmitting and receiving the wireless signal from all horizontal directions. On the other hand, when the smart antenna module operates in the directional mode, the radiation pattern of the smart antenna module may be a directional radiation pattern once a direction of the source of the wireless signal is confirmed. In addition, a direction of a main beam of the directional radiation pattern may also be adaptively adjusted to substantially face the direction of the source of the wireless signal, so as to perform the beam steering. As a result, the smart antenna module may be used as a switched-beam antenna to switch to either the omni-directional radiation pattern or the directional radiation pattern, thereby the co-channel fading may be improved and data throughput of the smart antenna module may be increased.
Specifically,
In structure, the smart antenna module 1 includes an omni-directional antenna 10, reflecting units 11, 12 and 13, a substrate 14 and a holder 15. A ground GND (not shown in
In operation, when the smart antenna module 1 is operating in the omni-directional mode, the radiation pattern of the smart antenna module 1 maybe an omni-directional pattern and all of the reflecting units 11, 12 and 13 are set at floating states. On the other hand, when the smart antenna module 1 is operating in the directional mode, one of the reflecting units 11, 12 and 13 is electrically connected to the ground GND, wherein one of the reflecting units 11, 12 and 13 may be regarded as a portion of the omni-directional antenna 10 for reflecting the omni-directional pattern of the smart antenna module 1, so that the radiation pattern of the smart antenna module 1 is the directional pattern. Moreover, a direction of a main beam of the directional pattern is substantially parallel to a direction from the reflecting unit electrically connected to the ground GND toward the omni-directional antenna 10. For example, the reflecting unit 11 maybe regarded as a portion of the omni-directional antenna 10 for reflecting the radiation pattern of the smart antenna module 1 when the reflecting unit 11 is grounded and the reflecting units 12 and 13 are floating, wherein the direction of the main beam of the directional pattern is substantially parallel to the direction from the reflecting unit 11 toward the omni-directional antenna 10 (i.e., an opposite direction of the x-direction).
As a result, the radiation pattern of the smart antenna module may be adjusted to the directional pattern by electrically connecting one of the reflecting units 11, 12 and 13 to the ground GND via the control signal, wherein the direction of the main beam may be one of three different directions. In an embodiment, the reflecting units 11, 12 and 13 may be evenly disposed around the omni-directional antenna 10, and lines from two adjacent reflecting units toward the omni-directional antenna 10 may form a central angle, wherein the two adjacent reflecting units maybe the reflecting units 11 and 12, the reflecting units 12 and 13 or the reflecting units 11 and 13 for example. The central angle maybe equal to 360/N, where N is a number of the reflecting units. In the embodiment shown in
In other words, the smart antenna module 1 of the present invention may control the reflecting units 11, 12 and 13 being connected to the ground GND and separated from the ground GND to adjust the radiation pattern of the smart antenna module 1. When the smart antenna module operates in the omni-directional mode, the radiation pattern of the smart antenna module 1 may be the omni-directional radiation pattern and all of the reflecting units 11, 12, 13 are separated from the ground GND. On the other hand, when the smart antenna module 1 operates in the directional mode, the radiation pattern of the smart antenna module 1 maybe the directional radiation pattern and one of the reflecting units 11, 12 and 13 is connected to the ground GND once the direction of the source of the wireless signal is confirmed. As a result, the smart antenna module 1 of the present invention maybe used as the switched-beam antenna to switch to either the omni-directional radiation pattern or the directional radiation pattern, thereby the co-channel fading maybe improved and data throughput of the smart antenna module can be increased.
Noticeably, the smart antenna module 1 in
Therefore, the smart antenna module 1 of the present invention may be switched to one of six different directions of the main beam via adjusting the ground states of the reflecting units. As a result, the beam steering may be more flexible.
In addition, relative positions between the reflecting units 11, 12 and 13 and the omni-directional antenna 10 may be adjusted according to practical requirements, which is not limited to the embodiment in
In structure, the smart antenna module 2 includes reflecting units 21, 22, 23 and 24. Assuming that the x-direction is at 0 degree, then the reflecting units 21, 22, 23 and 24 may be disposed at 0 degree, 90 degrees, 180 degrees and 270 degrees around the omni-directional antenna 10, respectively. A holder 25 of the smart antenna module 2 maybe coupled to the omni-directional antenna 10 and the reflecting units 21, 22, 23 and 24 to enhance a firmness of the omni-directional antenna 10 and the reflecting units 21, 22, 23, 24.
In operation, when the smart antenna module 2 is operating in the omni-directional mode, the radiation pattern of the smart antenna module 2 may be the omni-directional radiation pattern and all of the reflecting units 21, 22, 23 and 24 are set at floating states. On the other hand, when the smart antenna module 2 is operating in the directional mode, the smart antenna module 2 may be switched to eight different directions of the main beam, so that the beam steering may be more flexible. The direction of the main beam corresponding to the ground states of the reflecting units may be categorized into the following Table 2:
Therefore, the smart antenna module of the present invention may be switched to one of different directions of the main beam via adjusting the ground states of the reflecting units and increasing the number of the reflecting units. As a result, the beam steering may be more flexible.
The reflector 110 includes a bend 111 and arms 112 and 113. The arm 112 may be coupled between the switch and the bend 111 and extend along the z-direction from the switch SW. One end of the arm 113 may be electrically connected to the bend 111, and another end of the arm 113 may be open. The arm 113 may extend from the bend 111 along a direction from the omni-directional antenna 10 toward the reflector 110 (i.e., the x-direction), but not limited thereto. In another embodiment, the arm 113 of the reflector which is open may extend from the bend 111 along a direction from the reflector 110 toward the omni-directional antenna 10 (i.e., the opposite direction of the x-direction).
A pad 143_L1 and the ground GND may be formed on the first surface of the substrate 14, and the reflector 110 may be formed on the first surface of the substrate 14 by soldering. A pad 144_L2 and the ground GND_L2 maybe formed on the second surface of the substrate 14. The signal vias SV may be used for electrically connecting the pad 143_L1 and the pad 144_L2. In addition, the ground vias GV may be formed around the switch SW for electrically connecting the ground GND and the ground GND_L2 . The switch SW may be disposed on the second surface of the substrate 14 in opposite to the first surface on which the radiator 100 is disposed. Such a configuration may be beneficial for manufacturing.
The switch SW includes at least one switch device (diodes D1 and D2 are used as an example in the present embodiment) and a radio-frequency choke device CK. Anodes of the diodes D1 and D2 of the present embodiment are coupled to the reflector 110, and cathodes of the diodes D1 and D2 may be coupled to the ground GND. Once two diodes are turned on to enhance the conductivity between the reflector 110 and the ground GND, the directivity of the main beam of the smart antenna module 1 may be increased. In other embodiments, the switch SW may include three (or more) switch devices or a single switch device. The switch device may be a PIN-diode (P-intrinsic-N Diode) or any radio-frequency switching device which is capable of being used as the switch, such as a PN diode, a transistor or a microelectromechanical system (MEMS) . The radio-frequency choke device CK may have one end coupled to the control signal CT_sig, and another end coupled to the anodes of the diodes D1 and D2 and the reflector 110 to prevent the total stability and characteristics of the antenna from being influenced by the control signal CT_sig, and also prevent noise currents of the CT_sig from being transmitted to the ground GND and the reflecting units. In addition, the radio-frequency choke device CK may prevent signals of the ground GND and the reflector 110 from being transmitted to the control signal CT_sig.
In operation, the diodes D1 and D2 may be simultaneously turned on to electrically connect the reflector 110 with the ground GND when the control signal CT_sig is at a high voltage level. The diodes D1 and D2 may be simultaneously turned off to separate the reflector 110 from the ground GND when the control signal CT_sig is at a low voltage level. Therefore, the control signal CT_sig may control the ground state of the reflector 110 to adjust the radiation pattern of the smart antenna module.
As shown in
In structure, the arm 701 may be electrically connected to the feed point FP and extend along the z-direction from the feed point FP. The arm 702 maybe electrically connected to the arm 701 and extend along the opposite direction of the x-direction from the arm 701. The arm 703 may be electrically connected between the arm 702 and the ground GND. The arm 703 includes branches 7031 and 7032 and a bend 7033. The branch 7031 may be electrically connected between the arm 702 and the bend 7033 and extend along the y-direction from the arm 702. The branch 7032 may be electrically connected between the bend 7033 and the ground GND and extend along the opposite direction of the z-direction from the bend 7033.
The arm 704 may be electrically connected to the arm 701 and extend along the x-direction from the arm 701. The arm 705 may be electrically connected between the arm 704 and the ground GND, and the arm 705 includes branches 7051 and 7052 and a bend 7053. The branch 7051 may be electrically connected between the arm 704 and the bend 7053 and extend along the opposite direction of the y-direction from the arm 704. The branch 7052 may be electrically connected between the bend 7053 and the ground GND and extend along the opposite direction of the z-direction from the bend 7053.
A combination of the arm 702 and the branch 7031 of the arm 703 may form a U-shape having an opening facing the y-direction. A combination of the arm 704 and the branch 7051 of the arm 705 may form a U-shape having an opening facing the opposite direction of the y-direction. The branch 7032 of the arm 703 may form a U-shape having an opening facing the x-direction. The branch 7052 of the arm 705 may form a U-shape having an opening facing the opposite direction of the x-direction.
The arm 701 has a length L1, the arm 702 and the arm 704 have a length L2, respectively. A sum of the length L1 and the length L2 may be substantially a quarter wavelength of the wireless signal RF_sig. The arm 703 and the arm 705 have a length L3, respectively. The length L3 may be substantially the quarter wavelength of the wireless signal RF_sig. Therefore, a total length of the arms 701, 702 and 703 may be substantially a half wavelength of the wireless signal RF_sig, and a total length of the arms 701, 704 and 705 may be substantially the half wavelength of the wireless signal RF_sig.
Notably, the radiator 700 may further include open-stubs 706 and 707 for enhancing radiation efficiencies of the radiator 700 to resonate the wireless signal RF_sig and matching of the antenna. The open-stub 706 may be electrically connected to where the arm 702 is connected to the arm 703. The open-stub 707 may be electrically connected to where the arm 704 is connected to the arm 705. In other words, the open-stubs 706 and 707 may be disposed at the quarter wavelength of the wireless signal RF_sig from the feed point FP to adjust an intensity of the wireless signal RF_sig at the quarter wavelength. In such a structure, the return loss of the antenna module 7 may be reduced, radiation efficiencies of the radiator 700 may be enhanced, and impedance differences of the antenna module 7 operating in the omni-directional mode and the directional mode maybe reduced.
To sum up, the smart antenna module of the present invention may control the ground state of at least one reflecting unit to adjust the radiation pattern of the smart antenna module. When the smart antenna module is operating in the omni-directional mode, its radiation pattern may be the omni-directional radiation pattern with all of the reflecting units set at floating states. On the other hand, when the smart antenna module operates in the directional mode, its radiation pattern may be a directional radiation pattern toward the direction of the source of the wireless signal. As a result, the smart antenna module may be used as a switched-beam antenna to switch its pattern to be either omni-directional or directional, thereby the co-channel fading may be improved and data throughput of the smart antenna module may be increased.
Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 104111141 | Apr 2015 | TW | national |
