Patent Application
20230216197
The present application claims priority to Chinese Patent Application No. 202210007640.X, filed Jan. 6, 2022, the entire content of which is incorporated herein by reference as if set forth fully herein.
The present disclosure relates to a communication system, and more specifically, to a multiband antenna.
Cellular communications systems are well known in the art. In a cellular communications system, a geographic area is divided into a series of regions that are referred to as “cells” which are served by respective base stations. The base station may include one or more base station antennas that are configured to provide two-way radio frequency (“RF”) communications with mobile subscribers that are within the cell served by the base station.
In many cases, each base station is divided into “sectors”. In perhaps the most common configuration, a small hexagonally shaped cell is divided into three 120° sectors, and each sector is served by one or more base station antennas that generate radiation patterns or “antenna beams” that have an azimuth half power beam width (HPBW) of approximately 65°. Typically, the base station antennas are mounted on a tower structure, with the antenna beams that are generated by the base station antennas directed outwardly. Base station antennas are often realized as linear or planar phased arrays of radiating elements.
In order to accommodate the ever-increasing volumes of cellular communications, cellular operators have added cellular services in a variety of new frequency bands. While in some cases it is possible to use linear arrays of so-called “wideband” or “ultra-wideband” radiating elements to provide service in multiple frequency bands, in other cases it is necessary to use different linear arrays or planar arrays of radiating elements to support service in the different frequency bands.
As the number of frequency bands has proliferated, increased sectorization has become more common (e.g., dividing a cell into six, nine or even twelve sectors), and the number of base station antennas deployed at a typical base station has increased significantly. However, due to local zoning ordinances and/or weight and wind loading constraints for the antenna towers, etc. there is often a limit as to the number of base station antennas that can be deployed at a given base station. In order to increase capacity without further increasing the number of base station antennas, so-called multi-band antennas have been introduced in which multiple arrays of radiating elements are included in a single antenna. One very common multi-band antenna includes one linear array of “low-band” radiating elements that are used to provide service in some or all of the 617 to 960 MHz frequency band, and two linear arrays of “mid-band” radiating elements that are used to provide service in some or all of the 1427 to 2690 MHz frequency band. These linear arrays of low-band and mid-band radiating elements are typically mounted in a side-by-side fashion.
In order to implement this type of multiband antenna in a commercially acceptable manner, the undesired parasitic coupling that may occur in the multiband antenna should be reduced as much as possible. These parasitic couplings may occur between the radiating element arrays of different frequency bands. These parasitic couplings may cause distortion of the radiation pattern, such as a reduction in the front-to-back ratio and an increase in HPBW.
In addition, in order to implement such multiband antenna in a commercially acceptable manner, the width of the base station antenna needs to be kept within an acceptable dimension range. It is desirable that the multiband antenna has a high degree of compactness and integration.
According to a first aspect of the present disclosure, a multiband antenna is provided, wherein the multiband antenna extends in the longitudinal direction, and the multiband antenna comprises: a first column of radiating elements mounted on a base surface of a reflecting plate, which is configured to operate in a first operating frequency band and comprises a plurality of first radiating elements arranged along the longitudinal direction; a second column of radiating elements mounted on the base surface of the reflecting plate, which is configured to operate in a second operating frequency band that is different from the first operating frequency band and comprises a plurality of second radiating elements arranged along the longitudinal direction; a first fence and a second fence located on both sides of the reflecting plate that extend forward from the base surface of the reflecting plate, wherein the first column of radiating elements and the second column of radiating elements are arranged in between the first fence and the second fence, the first fence and the second fence respectively comprise a frequency selective surface with a passband and a stopband, the passband covers at least the first operating frequency band, and the stopband covers at least the second operating frequency band.
According to a second aspect of the present disclosure, a multiband antenna is provided, wherein the multiband antenna comprises: a first column of radiating elements mounted on a base surface of a reflecting plate, which is configured to operate in a first operating frequency band; a second column of radiating elements mounted on the base surface of the reflecting plate, which is configured to operate in a second operating frequency band that is different from the first operating frequency band; a first fence and a second fence located on respective opposed sides of the reflecting plate that extend forward from the base surface of the reflecting plate, wherein the first column of radiating elements and the second column of radiating elements are arranged in between the first fence and the second fence, the first fence and the second fence are configured to improve the front-to-back ratio of the radiation pattern generated by the second column of radiating elements, and the first fence and the second fence respectively comprise a frequency selective surface that is grounded to the reflecting plate.
Other features and advantages of the present disclosure will be made clear by the following detailed description of exemplary embodiments of the present disclosure with reference to the attached drawings.
Note, in the embodiments described below, the same reference signs are sometimes jointly used between different attached 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. Therefore, once an item is defined in one attached drawing, it does not need to be further discussed in subsequent attached drawings.
For ease of understanding, the position, dimension, and range of each structure shown in the attached drawings and the like may not indicate the actual position, dimension, and range. Therefore, the present disclosure is not limited to the position, size, range, etc. disclosed in the attached drawings.
The present disclosure will be described below with reference to the attached drawings, which show several examples of the present disclosure. However, it should be understood that the present disclosure can be presented in many different ways and is not limited to the examples described below. In fact, the examples described below are intended to make the present disclosure more complete and to fully explain the protection scope of the present disclosure to those skilled in the art. It should also be understood that the examples disclosed in the present disclosure may be combined in various ways so as to provide more additional examples.
It should be understood that the terms used herein are only used to describe specific examples, and are not intended to limit the scope of the present disclosure. All terms used herein (including technical terms and scientific terms) have meanings normally understood by those skilled in the art unless otherwise defined. For brevity and/or clarity, well-known functions or structures may not be further 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, if an element is described as “directly” “on” another element, “directly attached” to another element, “directly connected” to another element, “directly coupled” to another element or “directly in contact with” another element, there will be no intermediate elements. 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.
In this Specification, elements, nodes or features that are “connected” together may be mentioned. Unless explicitly stated otherwise, “connected” means that one element/node/feature can be mechanically, electrically, logically or otherwise connected with another element/node/feature in a direct or indirect manner to allow interaction, even though the two features may not be directly connected. That is, “connected” means direct and indirect connection of components or other features, including connection using one or a plurality of intermediate components.
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 rotates reversely, 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 by other means (rotated by 90 degrees or at other locations), and at this time, 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 term “exemplary” means “serving as an example, instance or explanation”, not as a “model” to be accurately copied”. Any realization method described exemplarily herein may not be necessarily interpreted as being preferable or advantageous over other realization methods. Furthermore, the present disclosure is not limited by any expressed or implied theory given in the above technical field, background art, summary of the invention or specific embodiments.
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 the divergence from the perfect or ideal situation due to parasitic effects, noise, and other practical considerations that may be present in the actual realization.
In addition, for reference purposes only, “first”, “second” and similar terms may also be used herein, and thus are not intended to be limitative. 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 term “comprise/include” is used herein, it indicates 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.
Fence structures and other parasitic elements are often used to shape the antenna beams generated by a base station antenna. Herein the term “parasitic element” refers to a conductive structure, that is not connected to an RF source, that are used to shape the radiation patterns generated by an array of radiating elements that is connected to the RF source. Parasitic elements may also be referred to as “tuning elements’ herein In a multiband antenna, undesired parasitic coupling may occur between a tuning element and one or more radiating elements. For example, a tuning element that is provided to adjust the shape of an antenna beam generated by a first array of radiating elements may also act to adjust the shape of an antenna beam generated by a second array of radiating elements, often in undesirable ways. The inventor found that: in some cases, a fence used to adjust the radiation pattern of a specific frequency band (for example, low frequency band) may negatively affect the radiation pattern of other frequency bands (for example, the medium frequency band). However, because the fence is important for the radiation pattern of the specific frequency band, such as the front-to-back ratio performance, the fence cannot simply be omitted. A new type of fence 10 comprising a frequency selective surface 20 is proposed for the multiband antenna 100 according to the present disclosure. The frequency selective surface 20 is capable of filtering electromagnetic waves in space. By periodically arranging a plurality of frequency selective surface units 22 on a two-dimensional plane, a metamaterial with a specific reflection/transmission phase distribution may be formed. When electromagnetic waves are incident on the frequency selective surface 20, the frequency selective surface 20 is able to selectively pass/block electromagnetic waves of different frequencies. Therefore, the multiband antenna 100 according to the present disclosure is capable of reducing the negative effect on the radiation pattern of other frequency bands (for example, medium frequency band) while maintaining the positive effect on the radiation pattern of a specific frequency band (for example, low frequency band).
An exemplary multiband antenna 100 according to some embodiments of the present disclosure will now be described in detail with reference to
As shown in
In the embodiments of
The multiband antenna 100 may further comprise, for example, a first fence 10-1 and a second fence 10-2 extending longitudinally on both sides of the reflecting plate, and the first fence 10-1 and the second fence 10-2 may extend forwardly from the base surface 2 of the reflecting plate. The first fence 10-1 and the second fence 10-2 may, together with the base surface 2 of the reflecting plate, form the reflecting plate. In general, the first fence 10-1 and the second fence 10-2 may be configured as an integrated structure with the base surface 2 of the reflecting plate (i.e., a single sheet of aluminum may be bent to form the base surface 2 of the reflecting plate and the first and second fences 10-1, 10-2). In some embodiments, the first fence 10-1 and the second fence 10-2 may also be separate from the base surface 2 of the reflecting plate. The first column of radiating elements 3 and the second column of radiating elements 4 may be arranged between the first fence 10-1 and the second fence 10-2.
The first fence 10-1 and the second fence 10-2 are capable of improving the radiation pattern performance of the radiating element array of a specific frequency band based on the parasitic coupling with the radiating element array of the specific frequency band. In the illustrated embodiment, the first fence 10-1 and the second fence 10-2 may be configured to improve the radiation pattern of the low-band radiating element array, for example, the front-to-back ratio performance of the radiation pattern. When the multiband antenna 100 is designed as a compact antenna, the first fence 10-1 and the second fence 10-2 become even more important for improving the front-to-back ratio performance of the radiation pattern of the low-band radiating element array, because the base surface 2 of the reflecting plate cannot be designed to have a wider dimension that is beneficial to the front-to-back ratio performance.
As shown in
However, the inventor also found that: The first fence 10-1 and the second fence 10-2 may negatively affect the radiation pattern of the mid-band radiating element array due to parasitic coupling, such as distorting the radiation pattern of the mid-band radiating element array. However, if the first fence 10-1 and the second fence 10-2 are removed, the front-to-back ratio performance of the radiation pattern of the low-band radiating element array will not meet the requirements. The way out of this dilemma is a technical problem that those skilled in the art urgently need to solve.
In order to minimize the undesired interference of the first fence 10-1 and the second fence 10-2 on the radiation pattern of the first column of radiating elements 3 (for example, the mid-band radiating element array) while keeping the first fence 10-1 and the second fence 10-2 in the multiband antenna 100, the first fence 10-1 and the second fence 10-2 may respectively comprise a frequency selective surface 20 with a passband and a stopband, such that the passband of the frequency selective surface 20 covers at least the first operating frequency band (for example, the medium frequency band), and the stopband of the frequency selective surface 20 covers at least the second operating frequency band (for example, the low frequency band). That is to say, when electromagnetic waves are incident on the frequency selective surface 20, the frequency selective surface 20 can pass electromagnetic waves in the first operating frequency band emitted by the first column of radiating elements 3 (for example, the mid-band radiating element array), and block and reflect electromagnetic waves in the second operating frequency band emitted by the second column of radiating elements 4 (for example, the low-band radiating element array). Thus, the undesired parasitic coupling between the first fence 10-1 and the second fence 10-2 and the mid-band radiating element array is avoided as much as possible while maintaining the desired parasitic coupling between the first fence 10-1 and the second fence 10-2 and the low-band radiating element array as much as possible.
In some embodiments of the present disclosure, the fence 10 may be integrally formed with the frequency selective surface 20. For example, the fence 10 may be constructed as a metal sheet, and the desired frequency selective surface 20 may be stamped on the fence 10. In some embodiments of the present disclosure, the fence 10 may be separately integrated with the frequency selective surface 20. For example, the fence 10 may be separately integrated with a printed circuit board on which the frequency selective surface 20 is printed. It is advantageous to arrange the frequency selective surface 20 on the sides of the first and second fences 10-1, 10-2 facing away from the first and second radiating element arrays 3, 4. That is, the frequency selective surface 20 of the first fence 10-1 and the frequency selective surface 20 of the second fence 10-2 are away from each other, so that the frequency selective surface 20 is as spaced from the first and second radiating element arrays 4 as possible. As a result, the aforementioned desired parasitic coupling is increased as much as possible, while the undesired parasitic coupling is reduced. When the multiband antenna 100 is a compact antenna, this arrangement is more advantageous.
Next, specific design solutions of the frequency selective surface 20 in the multiband antenna 100 of some embodiments of the present disclosure will be described in detail with reference to
As shown in
An advantageous design solution of the frequency selective surface unit 22 as a bandpass filter is shown in
In other embodiments, the first fence 10-1 and the second fence 10-2 may comprise a first frequency selective surface section and a second frequency selective surface section, respectively. For example, the fences 10-1, 10-2 may be configured to extend farther forwardly and the slot pattern illustrated in
It should be understood that there may be various design forms of the frequency selective surface 20 and it is not limited to the specific embodiments listed here. The resonant frequency point and/or operating bandwidth of the frequency selective surface 20 may be adjusted by designing various sizes of the frequency selective surface unit 22 to meet the requirements of different resonance points, multi-frequency resonance, and/or broadband resonance in different application scenarios.
Furthermore, the inventor also noted that: in order to maintain a beneficial effect on the front-to-back ratio performance of the low-band radiation pattern, common grounding of the frequency selective surface 20 and the reflecting plate may be implemented. In other words, the frequency selective surface 20 may be grounded to the reflecting plate.
In the embodiment of
In the embodiment of
Although some specific embodiments of the present disclosure 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 disclosure. The examples disclosed herein can be combined arbitrarily without departing from the spirit and scope of the present disclosure. Those skilled in the art should also understand that various modifications can be made to the examples without departing from the scope and spirit of the present disclosure. The scope of the present disclosure is defined by the Claims attached.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202210007640.X | Jan 2022 | CN | national |
