The present application is a 35 U.S.C. § 371 national stage application of PCT Application No. PCT/US2019/045612, filed Aug. 8, 2019, which itself claims priority to Chinese Patent Application No. 201810983849.3, filed Aug. 28, 2018, the entire contents of both of which are incorporated herein by reference in their entireties. The above-referenced PCT Application was published in the English language as International Publication No. WO 2020/046551 A1 on Mar. 5, 2020.
The present invention generally relates to multi-band antennas and, more specifically, to multi-band antennas with asymmetric radiating elements.
In multi-band antennas, radiating elements of different frequency bands may interfere with each other. For example, a low-band radiating element may generate interfering signals that fall within the operating frequency band of a high-band radiating element, thereby affecting the performance, such as the beam width and the like, of the high-band radiating element. In the prior art, such interfering signals may, for example, be suppressed by an arrangement of chokes on the low-band radiating element. However, the chokes may deteriorate the return loss performance of the low-band radiating element.
According to a first aspect of the present invention, there is provided a first band radiating element comprising at least one first band dipole, where the first band dipole has a first dipole arm and a second dipole arm, and each of the dipole arms includes one or more arm segments, and the number of the arm segments of the first dipole arm is greater than the number of the arm segments of the second dipole arm.
In some embodiments, the number of the arm segments of the first dipole arm and the second dipole arm may be adapted based on the requirements in the aspects of “transparency performance” (i.e., the interference or scattering of the first band radiating element itself to the radiating elements of other bands, where the lower the interference or scattering, the better the “transparency performance”) and in terms of return loss performance. For example, for optimizing the transparency performance, the number of the arm segments of dipole arms, in particular the number of the arm segments of the first dipole arm, may be increased. In contrast, for optimizing the return loss performance, the number of the arm segments of dipole arms, in particular the number of the arm segments of the second dipole arm, may be reduced.
In some embodiments, the multi-band antenna further includes a second band radiating element.
In some embodiments, the first band radiating element may be a low-band radiating element, for example covering the 617 MHz to 960 MHz frequency band or a portion thereof. The second band radiating element may be a high-band radiating element, for example covering the 1695 MHz to 2690 MHz frequency band or a portion thereof. The multi-band antenna may also include radiating elements that operate in other frequency bands.
In some embodiments, the second dipole arm is spaced farther from the second band radiating element than the first dipole arm.
In some embodiments, the second band radiating element is disposed in the vicinity of regions underneath the first dipole arm and remote from regions underneath the second dipole arm.
Since the number of the arm segments of the first dipole arm is greater than the number of the arm segments of the second dipole arm, arranging the first dipole arm near the second band radiating element may realize improved “transparency performance for the first band radiating element. Furthermore, as the second dipole arm is remote from the second band radiating element and has fewer arm segments, the return loss performance of the first band radiating element may also be improved.
In some embodiments, the first dipole arm is arranged opposite the second dipole arm at an angle of 180 degrees.
In some embodiments, the first dipole arm and the second dipole arm each includes a central conductor and a plurality of arm segments arranged around the central conductor, where the plurality of arm segments are spaced apart from each other along the central conductor.
In some embodiments, the arm segment includes a hollow electrical conductor, wherein the hollow electrical conductor is connected at one end to the central conductor and disconnected at the other end from the central conductor, thereby forming a so-called “choke”, that is, a gap between the hollow electrical conductor and the central conductor and a gap between the individual hollow electrical conductors. As a result, the interfering signals generated by the first band radiating element, that fall within the operating band range of the other band radiating element, such as the second band radiating element, are suppressed. The length of each arm segment may be adapted according to the operating frequency band of the radiating elements of the other band, such as the second band radiating element.
In some embodiments, the central conductor has a plurality of protrusions disposed axially on the central conductor from one end of the central conductor and spaced apart from each other, thereby dividing the central conductor into a plurality of electrically conducting segments, said hollow electrical conductor and said central conductor being connected on said protrusions.
In some embodiments, the hollow electrical conductor and the central conductor may be made of aluminum. During manufacturing, the hollow electrical conductor may be pressed onto the protrusion of the central conductor to form an electrical connection. The hollow electrical conductor and/or the central conductor may also be made of other suitable metals.
In some embodiments, at least two protrusions in the second dipole arm that are spaced apart from each other are connected by the hollow electrical conductor. As a result, at least two originally spaced-apart arm segments become one arm segment, thereby reducing at least one gap between the individual hollow electrical conductors and thus reducing the return loss.
In some embodiments, at least two adjacent protrusions in the second dipole arm are connected by the hollow electrical conductor.
In some embodiments, the hollow electrical conductor which connects the at least two spaced apart protrusions, is disposed in an end region or a middle region of the second dipole arm.
In some embodiments, there is no electrically conducting segment between the at least two spaced apart protrusions. That is, the electrically conducting segment between the at least two adjacent protrusions is removed. This can significantly reduce the manufacturing cost of the radiating element without reducing the reliability of the radiating element.
In some embodiments, the hollow electrical conductor is configured as a hollow cylindrical structure.
In some embodiments, gaps are present between the hollow electrical conductor and the central conductor. In some embodiments, the gaps may be filled with air, or the gaps may be completely or partly filled with dielectric material.
In some embodiments, the first dipole arm and the second dipole arm are constructed on a printed circuit board (“PCB”).
In some embodiments, the first band radiating element is a low-band radiating element and the second band radiating element is a high-band radiating element.
In some embodiments, the first dipole arm and the second dipole arm each have a plurality of arm segments that are spaced apart from each other, and the plurality of arm segments are connected via a filter mechanism.
In some embodiments, the filter mechanism comprises an inductive element or a combination of the inductive element and a capacitive element.
In some embodiments, the filter mechanism exhibits a high impedance characteristic in the second band and a low impedance characteristic in the first band.
According to a second aspect of the present invention, there is provided a multi-band antenna comprising the first band radiating element and the second band radiating element according to the present invention, where the first band is different from the second band.
The present invention will be described below with reference to the drawings, in which several embodiments of the present invention are shown. It should be understood, however, that the present invention may be implemented in many different ways, and is not limited to the example embodiments described below. The embodiments described hereinafter are intended to make a more complete disclosure of the present invention and to adequately explain the protection scope of the present invention to a person skilled in the art. It should also be understood that, the embodiments disclosed herein can be combined in various ways to provide many additional embodiments. For the sake of conciseness and/or clarity, well-known functions or constructions may not be described in detail.
The singular forms “a/an”, “said” and “the” as used in the specification, unless clearly indicated, all contain the plural forms. The words “comprising”, “containing” and “including” used in the specification indicate the presence of the claimed features, but do not preclude the presence of one or more additional features. The wording “and/or” as used in the specification includes any and all combinations of one or more of the relevant items listed.
In the specification, words describing spatial relationships such as “up”, “down”, “left”, “right”, “forth”, “back”, “high”, “low” and the like may describe a relation of one feature to another feature in the drawings. It should be understood that these terms also encompass different orientations of the apparatus in use or operation, in addition to encompassing the orientations shown in the drawings. For example, when the apparatus in the drawings is turned over, the features previously described as being “below” other features may be described to be “above” other features at this time. The apparatus may also be otherwise oriented (rotated 90 degrees or at other orientations) and the relative spatial relationships will be correspondingly altered.
It should be understood that, in all the drawings, the same reference signs present the same elements. In the drawings, for the sake of clarity, the sizes of certain features may not always be drawn to scale.
A first band radiating element of the present invention is applicable to various types of multi-band antennas, and is particularly suitable for multi-band antennas with interspersed radiating elements (for example, ultra-wideband dual-band dual-polarization antennas). The term “dual band antenna” refers herein to an antenna that has two different types of radiating elements that are designed to operate in two different frequency bands, which are typically referred to as the “low band” and the “high band.” For example, a common dual band antenna design includes one or more arrays of low band radiating elements that operate in the 617 MHz to 960 MHz frequency band, or one or more portions thereof, and one or more arrays of “high band” radiating elements that operate in the 1695 MHz to 2690 MHz” frequency band, or one or more portions thereof. Herein, the term “multi-band antenna” refers to an antenna that has two or more different types of radiating elements that are designed to operate in different frequency bands, and encompasses both dual band antennas and antennas that support service in three or more frequency bands.
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A principal challenge in the design of multi-band antennas with interspersed radiating elements is reducing the scattering-interference of radiating elements at one band to the radiating elements of the other band, as the scattering affects the beam forming performance of the antenna. In a dual-band, dual-polarization antenna with interspersed radiating elements, in order to reduce the scattering-interference of the low-band radiating elements on the high-band radiating elements, it may be advantageous to introduce a plurality of spaced-apart arm segments in the dipole arms of the low-band radiating elements that act as radio frequency chokes, because the introduction of one or more chokes that are resonant at or near the high band can effectively reduce the scattering-interference of the low-band radiating elements on the high-band radiating elements.
Each hollow electrical conductor is connected at one end to the electrically conducting segment 10 through a radially-extending protrusion 9 of the central conductor 7, that is, each arm segment 6 is short-circuited at one end to the central conductor 7. Each hollow electrical conductor is disconnected at the other end from the electrically conducting segment 10 of the central conductor 7, that is, the arm segment 6 is open-circuited at the other end to the central conductor 7. As a result, so-called chokes, that is, a gap between the hollow electrical conductor 8 and the central conductor 7 and a gap between the individual hollow electrical conductors 8, are formed. These gaps may typically be filled with air so that a better signal suppression effect may be realized; in other embodiments, these gaps may also be completely or partly filled with other dielectric materials.
The number and length of arm segments 6 may be adjusted according to the actual operating frequency of the high-band radiating elements 2, so as to reduce the scattering-interference of the low-band radiating elements 1 within the actual operating band range of the high-band radiating elements 2, thereby improving the transparency performance of the low-band radiating element 1 with respect to the high-band radiating element 2. However, as the number of arm segments 6 included on the dipole arm is increased, the return loss performance of the low-band radiating element 1 itself may deteriorate. The return loss, which is also referred to as reflection loss, is mainly caused by reflection due to impedance mismatch, and is measured as a ratio of the reflected wave power to the incident wave power. Since with the increase in number of the arm segments, the impedance of the dipole arm may become very large, matching the impedance of the dipole arm to the impedance of the feed stalk 5 may become increasingly difficult, resulting in degraded return loss performance.
Referring now to
The first dipole arm 301 has a structure similar to that of the prior art, as is shown in
The arm segment 601 is constructed as a hollow electrical conductor having a hollow tubular or cylindrical structure. The second dipole arm 401 has three arm segments 601, namely an intermediate arm segment, an outer arm segment (i.e. the arm segment remote from the feed end) and an inner arm segment (i.e. the arm segment close to the feed end) on both sides, in which the intermediate arm segment is longer than the outer arm segment and the inner arm segment. On the outer arm segment and the inner arm segment, the hollow electrical conductor is connected at one end to the electrically conducting segment 1001 through a protrusion 901 of the central conductor 701, and is disconnected at the other end from the electrically conducting segment 1001 of the central conductor 701, thereby forming a choke. On the intermediate arm segment, the hollow electrical conductor extends over two adjacent protrusions 901 and is connected at its one end and middle position to the two protrusions 901 respectively. The intermediate arm segment may be approximately twice the length of the outer arm segment or the inner arm segment. Since the number of the arm segments on the second dipole arm is decreased, the impedances become smaller and matching of the impedances becomes less difficult, thereby improving the return loss performance of the low-band radiating element.
Referring now to
With respect to the low-band radiating element 101 in the first embodiment, the first dipole arm 301 that is close to the array of high-band radiating elements 201 has four arm segments, while the second dipole arm 401 that is remote from the array of high-band radiating elements 201 has three arm segments. This arrangement maintains the scattering-interference of the low-band radiating element 101 on the high-band radiating element 201 at a low level, that is, the transparency performance is good, and improves the return loss performance of the low-band radiating element 101, thereby improving the performance of the dual-band antenna as a whole.
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Although the exemplary embodiments of the present invention have been described, a person skilled in the art should understand that, multiple changes and modifications may be made to the exemplary embodiments without substantively departing from the spirit and scope of the present invention. Accordingly, all the changes and modifications are encompassed within the protection scope of the present invention as defined by the claims. The present invention is defined by the appended claims, and the equivalents of these claims are also contained therein.
Number | Date | Country | Kind |
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201810983849.3 | Aug 2018 | CN | national |
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PCT/US2019/045612 | 8/8/2019 | WO |
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WO2020/046551 | 3/5/2020 | WO | A |
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Number | Date | Country | |
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20210320433 A1 | Oct 2021 | US |