Patent Grant
11909103
The present invention relates to a communication system, and more particularly, to a base station antenna for a cellular communication system.
Base station antennas used in wireless communication systems are used to transmit radio frequency (“RF”) signals to and receive RF signals from fixed and mobile users of cellular communication services. Base station antennas generally comprise a linear array or a two-dimensional array of radiating elements, such as crossed dipoles or patch radiating elements. In order to increase the system capacity, beamforming base station antennas are being deployed at present, which comprise a plurality of closely spaced linear arrays of radiating elements (simply referred to as “arrays” or “columns” herein). A typical goal of an antenna with such beamforming capabilities is to generate a narrow antenna beam in the azimuth plane. The RF signals emitted by the radiating elements of the different columns combine to create this antenna beam. This increases the signal power transmitted in the desired user direction and reduces interference.
If the arrays of radiating elements in the beamforming antenna are closely spaced, the antenna beam can be scanned to a very wide angle in the azimuth plane (e.g., 60°) without generating large magnitude sidelobes. However, as the arrays are spaced more closely together, the mutual coupling between the radiating elements in adjacent arrays increases, which reduces other performance parameters of the base station antenna, such as co-polarization performance. In order to maintain close spacing between adjacent arrays of beamforming antennas and increase isolation between radiating elements in adjacent arrays, it may be necessary to stagger adjacent arrays in the longitudinal direction of the base station antenna, which increases the physical spacing between “adjacent” radiating elements in “adjacent” arrays. This staggered structure reduces the mutual coupling between adjacent elements, thus increasing the isolation.
As shown in
When the phase centers of a first element X and a second element Y are basically aligned, the phase of electromagnetic radiation of element X is basically consistent with that of element Y at any point on the elevation plane (i.e., at any elevation angle). The elements X and Y may each be a single radiating element, a combination of radiating elements, a sub-array, a combination of sub-arrays, an array, etc.
Two adjacent arrays in the arrays 21 to 24 are staggered in the longitudinal direction. For example, the longitudinal position of each radiating element 2 in array 21 is staggered with respect to that of the corresponding radiating element 2 in array 22, as shown by the dotted lines B and C in
The above-mentioned feeding configuration of arrays 21 to 24 not only results in a stagger of the phase centers of corresponding sub-arrays between adjacent arrays, but also staggers the phase centers of adjacent arrays. For example, the phase center of array 21 is offset upward from the phase center of array 22. This phase center offset between adjacent arrays causes spatial phase difference between arrays, which will distort the radiation pattern of antenna beams formed by these arrays.
In addition, it is also desirable to electrically adjust the elevation angle of the antenna beams generated by the beamforming antenna so as to adjust the coverage area of the antenna in the elevation plane. This can be done separately for each array using the electromechanical phase shifters. However, the disadvantage is that, with the increase of the applied electrical tilt angle, the distortion to the antenna beam caused by the offset of the phase centers of adjacent arrays may increase. To compensate for this distortion, different amplitudes and/or phase weights can be adopted for different radiating element arrays. However, including this compensation system will increase the design difficulty and/or cost of the antenna system.
According to the first aspect of the present invention, a base station antenna is provided, comprising: a first array that includes a plurality of first radiating elements arranged along the longitudinal direction of the base station antenna; and a second array that includes a plurality of second radiating elements arranged along the longitudinal direction of the base station antenna, the second array transversely adjacent the first array, wherein the longitudinal position of each second radiating element is staggered from that of the corresponding first radiating element, wherein, the first array comprises first and second sub-arrays, each of which comprises one or a plurality of adjacent first radiating elements, and wherein a phase center of the combination of the first and second subarrays is basically aligned with a sub-phase center of the second array.
According to a second aspect of the present invention, a base station antenna is provided, comprising: a first column of radiating elements, wherein the first column has a first sub-phase center; and a second column of radiating elements transversely adjacent to the first column, the longitudinal positions of the first column and the second column being staggered by a first staggered amount, wherein the second column has a second sub-phase center, the longitudinal positions of the first sub-phase center and the second sub-phase center are basically aligned, the first column comprises first and second subsets of radiating elements, and a phase center of the combination of the first and second subsets basically coincides with the first sub-phase center.
According to a third aspect of the present invention, a base station antenna is provided, comprising: a first column of radiating elements, wherein the first column comprises a first phase center; and a second column of radiating elements adjacent to the first column, wherein the second column comprises a second phase center, the first and second columns are staggered in the longitudinal direction of the base station antenna, the first and second phase centers are basically aligned, the first column comprises first and second subsets, and any one of the first and second subsets comprises one or a plurality of adjacent radiating elements, and the phase center of the combination of the first and second subsets basically coincides with the first phase center.
According to a fourth aspect of the present invention, a base station antenna is provided, comprising: a first array that includes a plurality of first radiating elements arranged along a longitudinal direction of the base station antenna; a second array that includes a plurality of second radiating elements arranged along the longitudinal direction of the base station antenna, the second array transversely adjacent the first array, wherein the longitudinal positions of the second radiating elements are staggered from the longitudinal positions of the first radiating elements, wherein a phase center of a first sub-array of the first array is a first distance above a phase center of the first array, wherein a phase center of a second sub-array of the first array is the first distance below the phase center of the first array, wherein a phase center of a first sub-array of the second array is a second distance above a phase center of the second array, wherein a phase center of a second sub-array of the second array is the second distance below the phase center of the second array, wherein the phase center of the first array and the phase center of the second array are aligned along a transverse direction, and wherein the first distance is different from the second distance.
According to a fifth aspect of the present invention, a base station antenna is provided, comprising: a first array that includes a plurality of first radiating elements arranged along a longitudinal direction of the base station antenna; and a second array that includes a plurality of second radiating elements arranged along the longitudinal direction of the base station antenna and transversely adjacent to the first array, wherein the longitudinal positions of the second radiating elements are staggered from that of the longitudinal positions of the first radiating elements, wherein a phase center of a combination of a first sub-array and a second sub-array of the first array is aligned along a transverse axis with a phase center of a combination of a first sub-array and a second sub-array of the second array.
Other features and advantages of the present invention will be made clear by the following detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings.
Note, in the embodiments described below, the same signs may be used in different drawings to denote the same parts or parts with the same functions, and repeated descriptions thereof are omitted. In some cases, similar labels and letters are used to indicate similar items.
For ease of understanding, the position, size, and range of each structure shown in the drawings and the like may not indicate the actual position, size, and range. Therefore, the present invention is not limited to the position, size, range, etc. disclosed in the drawings.
The present invention will be described below with reference to the accompanying drawings, which show several embodiments of the present invention. However, it should be understood that the present invention can be presented in many different ways and is not limited to the embodiments described below. In fact, the embodiments described below are intended to make the present invention more complete and to fully explain the protection scope of the present invention to those skilled in the art. It should also be understood that the embodiments disclosed herein may be combined in various ways so as to provide additional embodiments.
It should be understood that the terms used herein are only used to describe specific embodiments, and are not intended to limit the scope of the present invention. All terms used herein (including technical terms and scientific terms) have meanings normally understood by those skilled in the art unless otherwise defined. Well-known functions or structures may not be described in detail.
As used herein, when an element is said to be “on” another element, “attached” to another element, “connected” to another element, “coupled” to another element, or “in contact with” another element, etc., the element may be directly on another element, attached to another element, connected to another element, coupled to another element, or in contact with another element, or an intermediate element may be present. In contrast, when an element is said to be “on” another element, “attached” to another element, “connected” to another element, “coupled” to another element, or “in contact with” another element, etc., no intermediate element may be present. As used herein, when one feature is arranged “adjacent” to another feature, it may mean that one feature has a part overlapping with the adjacent feature or a part located above or below the adjacent feature.
As used herein, spatial relationship terms such as “upper”, “lower”, “left”, “right”, “front”, “back”, “high” and “low” can explain the relationship between one feature and another in the drawings. It should be understood that, in addition to the orientations shown in the attached drawings, the terms expressing spatial relations also comprise different orientations of a device in use or operation. For example, when a device in the attached drawings is turned upside down, the features originally described as being “below” other features now can be described as being “above” the other features. The device may also be oriented in other directions (rotated by 90 degrees or in other orientations), and in this case, a relative spatial relation will be explained accordingly.
As used herein, the term “A or B” comprises “A and B” and “A or B”, not exclusively “A” or “B”, unless otherwise specified.
As used herein, the word “basically” means including any minor changes caused by design or manufacturing defects, device or component tolerances, environmental influences, and/or other factors. The word “basically” also allows for deviation from the perfect or ideal situation due to parasitic effects, noise, and other practical considerations that may be present in the actual implementation.
In addition, for reference purposes only, “first”, “second” and similar terms may also be used herein, and thus are not intended to be limiting. For example, unless the context clearly indicates, the words “first”, “second” and other such numerical words involving structures or elements do not imply a sequence or order.
It should also be understood that when the terms “comprise” and “include” and other forms thereof indicate the presence of the specified feature, entirety, step, operation, unit and/or component, but does not exclude the presence or addition of one or a plurality of other features, steps, operations, units and/or components and/or combinations thereof.
It should be noted that, as used herein, phase centers other than the phase center of an entire array, such as the phase centers of radiating elements, phase centers of sub-arrays and the phase centers of the combination of sub-arrays, are also called “sub-phase centers” of arrays.
The radiating elements in each array can be divided into sub-arrays, and each sub-array is coupled to a corresponding output of the phase shifter. In adjacent arrays 41 and 42, the phase centers of sub-array 411 of array 41 and sub-array 421 of array 42, and those of sub-arrays of 413 and 423, and those of sub-arrays of 415 and 425, are basically aligned, while the phase centers of sub-arrays 412 and 422, and those of sub-arrays of 414 and 424 are staggered by a distance s. It can be understood that because the longitudinal positions of the arrays 41 and 42 are staggered, the numbers of radiation elements comprised in the sub-arrays whose phase centers are basically aligned at the corresponding positions of the two arrays are different. For example, the phase-aligned sub-arrays shown in the figure comprise two and three radiating elements, respectively. It should be understood that sub-arrays including other numbers of radiating elements can also be phase-aligned, for example, sub-arrays respectively including one and two radiating elements, sub-arrays respectively including one and four radiating elements, etc.
If the phase centers of all sub-arrays in one array are aligned with the phase centers of the corresponding sub-arrays in an adjacent array, then the phase centers of the two arrays are aligned. Therefore, those aligned sub-arrays will not make the phase centers of the two arrays staggered. For the convenience of analysis, only the sub-arrays 412, 414, 422, 424 with misaligned phase centers in the arrays 41 and 42 are shown in
φ1=−φ0+6kd sin θ
φ2=−φ0+5.5kd sin θ
φ3=0+5kd sin θ
φ4=0+4.5kd sin θ
φ5=φ0+1.5kd sin θ
φ6=φ0+kd sin θ
φ7=0+0.5kd sin θ
φ8=0
where φ0 is the preset phase difference (for example, caused by the feeding line) between two radiating elements in a sub-array (for example, a group of radiating elements which are coupled to the output of the same phase shifter and fed by the same feeding plate), k is the transmission coefficient of electromagnetic waves in vacuum, and its value is
When the electronic downtilt angle is θ, the phase of the combination of sub-arrays 412 and 414 at the specific elevation angle is −0.5φ0+3kd sin θ. In particular, the phase of sub-array 412 is the average of the phase centers of radiating elements 55 whose phase is j−φ0+1.5kd sin θ and 57 whose phase is 0+0.5kd sin θ, which is −0.5φ0+kd sin θ. Similarly, the phase of sub-array 414 is the average of the phase centers of radiating elements 52 whose phase is −φ0+5.5kd sin θ and 54 whose phase is 0+4.5kd sin θ, which is −0.5φ0+5kd sin θ. The phase of the combination of sub-arrays 412 and 414 at the specific elevation angle of the elevation plane is −0.5φ0+3kd sin θ. The phase of the combination of sub-arrays 422 and 424 at the specific elevation angle of the elevation plane can similarly be calculated as −0.5φ0+3kd sin θ. It can be seen that the phase of the combination of sub-arrays 412 and 414 is consistent with that of the combination of sub-arrays 422 and 424, and this is true for any elevation angle. That is, at any point on the elevation plane, the phase of the combination of sub-arrays 412 and 414 is consistent with that of the combination of sub-arrays 422 and 424. Therefore, the phase center of the combination of sub-arrays 412 and 414 is aligned with the phase center of the combination of sub-arrays 422 and 424. It should be noted that although sub-arrays 412 and 414 of array 41 are coupled to different outputs of the phase shifter, they are all fed by the same phase shifter. The phase shifter has only one input (usually connected with radio devices other than the base station antenna by cable), that is, the time that the signal is fed to the sub-array 412 is the same as the time that the signal is fed to the sub-array 414, so the electromagnetic radiation of the sub-array 412 and that of the sub-array 414 can be superimposed in space, and the concept of the phase or phase center of the combination of the sub-arrays 412 and 414 exists. The same is true for sub-arrays 422 and 424.
In sum, in adjacent arrays 41 and 42, the phase centers of sub-arrays 411 and 421, sub-arrays 413 and 423, and sub-arrays 415 and 425 are basically aligned, and the phase centers of sub-arrays 412 and 414, and sub-arrays 422 and 424 are also basically aligned, so the phase center of array 41 is basically aligned with that of array 42. In the base station antenna according to this embodiment of the present invention, by designing the feeding configuration of two adjacent arrays of radiating elements, the phase centers of two arrays with staggered positions are aligned as much as possible, so that the base station antenna not only has the advantage of staggered array positions, but also can reduce or even eliminate the adverse effects caused by the misalignment of phase centers between arrays.
Thus, the base station antenna of
The first array 41 may comprise a first column of first radiating elements, and the second array 42 may comprise a second column of second radiating elements that is transversely adjacent the first column. The longitudinal positions of the first column and the second column are staggered by a first staggered amount. The first column has a first sub-phase center (e.g., the phase center of sub-array 413) and the second column has a second sub-phase center (e.g., the phase center of sub-array 423), and the longitudinal positions of the first and second sub-phase centers are basically aligned. The first column comprises first and second subsets of radiating elements (e.g., sub-arrays 412, 414), and a phase center of the combination of the first and second subsets basically coincides with the first sub-phase center.
As can also be seen in
The difference between the first distance and the second distance is less than the distance “d” between two adjacent first radiating elements in the first array. The difference between the first distance and the second distance may equal to half the distance “d” between two adjacent first radiating elements in the first array. As can also be seen from
It should be noted that each array 41-44 includes radiating elements that are exactly aligned along respective longitudinal axes. It will be appreciated that in other cases, the arrays/columns 41-44 may have some degree of horizontal stagger.
The positions of the two combined sub-arrays in the arrays can be arranged as required. Combined with the above description with reference to
For example, in the embodiment shown in
In the above embodiments, the sub-arrays that are combined with each other to have matching phase centers with a combination of sub-arrays in an adjacent array have two radiating elements. It should be understood that other numbers of radiating elements can be included in the sub-arrays that are combined with each other. For example, in the embodiment shown in
In some cases, the phase centers of the arrays can be slightly staggered. As long as the staggered amount of the phase centers of the arrays is smaller than the staggered amount of the physical centers of the arrays, it can obtain smaller distortion than the arrays with the feeding mode shown in
In the above-described embodiment, the feeding configurations of arrays 43 and 44 are the same as those of arrays 41 and 42, respectively, so they will not be described again. In the embodiment described below, only two adjacent arrays 61 and 62 of the base station antenna are shown. It should be understood that the base station antenna can also comprise more arrays with similar feeding configurations or arrays with other known feeding configurations.
In some cases, the physical centers of two adjacent arrays are basically aligned. For example, the numbers of radiating elements in two arrays differ by one. In these cases, it is only necessary to adjust the phase center of each array to the physical center of the array by designing the feeding configuration so as to make the phase centers of two adjacent arrays basically aligned. In addition, adjacent arrays may not even comprise sub-arrays with aligned phase centers. In the embodiment shown in
In the above embodiments, the sub-arrays combined with each other all contain more than one radiating element. In the embodiment shown in
The number of radiating elements contained in the combined sub-arrays of one array may be different from that of radiating elements contained in the combined sub-arrays of another array. In the embodiment shown in
Although some specific embodiments of the present invention have been described in detail by examples, those skilled in the art should understand that the above examples are only for illustration, not for limiting the scope of the present invention. The embodiments disclosed herein can be combined arbitrarily without departing from the spirit and scope of the present invention. Those skilled in the art should also understand that various modifications can be made to the embodiments without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the claims attached.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202010901489.5 | Sep 2020 | CN | national |
The present application is a continuation under 35 U.S.C. § 120 of U.S. patent application Ser. No. 17/153,958, filed Jan. 21, 2021, which in turn claims priority to Chinese Patent Application No. 202010901489.5, filed Sep. 1, 2020, the entire content of each of which is incorporated herein by reference as if set forth fully herein.
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| Number | Date | Country | |
|---|---|---|---|
| Parent | 17153958 | Jan 2021 | US |
| Child | 18123392 | US |
