Base station antenna having an array with frequency-selective shared radiation elements

Abstract

The present invention discloses a base station antenna having an array with frequency-selective shared radiating elements. The base station antenna includes a first radiating element array coupled to a first RF port through a first feeding network, a second radiating element array coupled to a second RF port through a second feeding network, and a first circuit element and a second circuit element. The first circuit element has a first port coupled to the first feeding network, a second port coupled to the first port of the second circuit element, and a third port coupled to the first radiating element of the first radiating element array. The second circuit element has a second port coupled to the first radiating element of the second radiating element array and a third port coupled to the second feeding network.

Description

Technical Field

[0001] The present invention relates to radio communication and, more particularly, to base station antennas for cellular communication. Background Art

[0002] Cellular communication systems are well known in the art. In a typical cellular communication system, a geographical area is divided into a series of regions called “cells”, and each cell is served by a base station. The base station may include baseband equipment, radio equipment, and a base station antenna, which are configured to provide two-way radio frequency (“RF”) communication with subscribers located throughout the cell. In many cases, a cell may be divided into multiple “sectors”, and different base station antennas provide coverage to each of the sectors. The antennas are often mounted on towers, and the radiation beams (“antenna beams”) generated by each antenna point outward to serve the corresponding sector. Generally, a base station antenna includes one or more phased arrays of radiating elements, and when the antenna is installed for use, the radiating elements are arranged in one or more vertical columns. In this document, “vertical” refers to a direction perpendicular to the horizontal plane defined by the horizon. Reference will also be made to the azimuth plane (which is the horizontal plane that bisects the base station antenna) and to the elevation plane (which is a plane perpendicular to the azimuth plane and extending in the direction pointed by the boresight of the antenna).

[0003] A common base station configuration is the “three-sector” configuration, in which a cell is divided into three 120° sectors in the azimuth plane. A base station antenna is provided for each sector. In the three-sector configuration, the antenna beam generated by each base station antenna typically has a half-power beam width (“HPBW”) of approximately 65° in the azimuth plane, such that each antenna beam provides good coverage throughout the 120° sector. Three of these base station antennas will provide full 360° coverage in the azimuth plane. Generally, each base station antenna will include a so-called “linear array” of radiating elements, which includes a plurality of radiating elements arranged in a vertically extending column. Each radiating element may have an azimuth HPBW of approximately 65°, such that the antenna beam generated by the linear array will have an HPBW of approximately 65° in the azimuth plane. By providing a column of radiating elements extending along the elevation plane, the HPBW of the antenna beam in the elevation plane can be narrowed to significantly less than 65°, and the amount of narrowing increases with the length of the column in the vertical direction.

[0004] As the demand for cellular services grows, cellular operators have upgraded their networks to support a new generation of services. When introducing these new services, it is often necessary to maintain existing "legacy" services to support legacy mobile devices. Therefore, as new services are introduced, new cellular base stations must be deployed or existing cellular base stations must be upgraded to support the new services. To reduce costs, many cellular base stations support two, three, four, or more generations of cellular services. However, due to local zoning regulations and / or weight and wind load restrictions, there are often limitations on the number of base station antennas that can be deployed at a given base station. To reduce the number of antennas, many operators have deployed antennas that communicate in multiple frequency bands to support a variety of different cellular services.

[0005] There has been considerable interest in base station antennas that include two linear arrays of radiating elements for providing service in some or all of the 1427 - 2690 MHz frequency band, which is often referred to as the "mid-band" frequency range. These two linear arrays of radiating elements are typically mounted side by side. Figure 1 is a schematic front view of a conventional base station antenna 10 that includes first and second columns 12-1, 12-2 of radiating elements 16. Each radiating element 16 is depicted as an "X" in Figure 1 (and other figures herein) to indicate that the radiating element is a dual-polarized cross-dipole radiating element. Each column 12-1, 12-2 of radiating elements 16 forms a respective linear array 14-1, 14-2 of radiating elements 16. An antenna having the Figure 1 configuration shown in can be used for various applications, including 4xMIMO (i.e., multiple-input multiple-output) applications, or as a multi-band antenna that supports cellular services in two different sub-bands within the 1427 - 2690 MHz frequency band (e.g., the linear arrays 14-1, 14-2 can operate in different non-overlapping frequency sub-bands among, for example, the 1427 - 1518 MHz, 1710 - 1880 MHz, 1850 - 1995 MHz, 1695 - 2180 MHz, 2300 - 2400 MHz, 2496 - 2690 MHz, and 2300 - 2690 MHz frequency sub-bands). In some cases, the linear arrays 14-1, 14-2 can be the only arrays included in the base station antenna 10, while in other cases, one or more additional arrays (not shown) of radiating elements operating in other frequency bands (such as the low-band frequency range (extending from 617 - 960 MHz) or the high-band frequency range (which can include the 3.4 - 3.8 GHz and / or 5.1 - 5.8 GHz frequency bands)) can also be included in the antenna 10.

[0006] It should be noted that, in this document, when multiple identical or similar elements are provided, they can be labeled in the drawings using a two-part reference number (e.g., array 14-1, 14-2). These elements can be individually referred to herein by their full reference number (e.g., array 14-2), and can be collectively referred to by the first part of their reference number (e.g., array 14). BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is a schematic front view of a conventional base station antenna including two linear arrays of radiating elements.

[0008] Figures 2A - 2C is a schematic front view of a number of conventional base station antennas having arrays of dual-polarized cross-dipole radiating elements with increased horizontal apertures that generate antenna beams with reduced azimuth HPBW.

[0009] Figure 3A ]>]is a schematic front view of a base station antenna according to an embodiment of the present invention.

[0010] Figure 3B is a schematic block diagram of a feed network for a base station antenna for Figure 3A .

[0011] Figure 4A is a front view of a printed circuit board-based duplexer that can be used to implement either or both of the first circuit element and / or the second circuit element of a base station antenna for Figure 3A .

[0012] Figure 4B is a graph showing the simulated response of a duplexer showing Figure 4A .

[0013] Figure 5A is a front view of a printed circuit board-based power splitter for a second circuit element of a base station antenna that can be used to implement Figure 3A , the power splitter having a low-pass filter at one of its outputs.

[0014] Figure 5B is a graph showing the simulated response of a power splitter / low-pass filter circuit showing Figure 5A .

[0015] Figure 6A is, compared to the azimuth HPBW of a comparable single-column linear array of radiating elements, for a duplexer using Figure 4A as the first circuit element and a splitter / low-pass filter circuit using Figure 5A as the second circuit element to implement Figures 3A - 3BGraph of simulated azimuth HPBW as a function of frequency for a second array of radiating elements of a base station antenna.

[0016] Figure 6B Yes, compared to the simulated gain of a comparable single-column linear array of radiating elements, for the use of Figure 4A as the first circuit element and Figure 5A as the second circuit element to implement the Figures 3A - 3B Graph of simulated gain as a function of frequency for a second array of radiating elements of a base station antenna.

[0017] Figure 7 Yes, compared to the azimuth HPBW of a comparable single-column linear array of radiating elements, for the use of Figure 4A as the first and second circuit elements to implement the Figures 3A - 3B Graph of simulated azimuth HPBW as a function of frequency for a second array of radiating elements of a base station antenna.

[0018] Figure 8A Is a schematic front view of a base station antenna according to a further embodiment of the present invention.

[0019] Figure 8B Is a schematic block diagram illustrating the feed network for a Figure 8A base station antenna.

[0020] Figure 9A Is a schematic front view of a base station antenna according to a further embodiment of the present invention, the base station antenna including three columns of radiating elements.

[0021] Figure 9B Is a schematic block diagram illustrating the feed network for a Figure 9A base station antenna.

[0022] Figure 10 Is a schematic block diagram illustrating a base station antenna according to a still further embodiment of the present invention. Detailed Description

[0023] One challenge in designing a base station antenna is that the azimuth beamwidth of the radiating elements tends to vary with frequency, where the azimuth beamwidth is wider when the radiating elements operate at lower frequencies and narrower when the radiating elements operate at higher frequencies. For an operating frequency range such as the traditional low band frequency range (690 - 960 MHz), this is not a significant problem because the operating frequency range is not that wide. More difficulties are encountered when designing a base station antenna with a linear array that can operate across the entire range of the traditional mid band operating frequency range (1695 - 2690 MHz), but a suitable design was ultimately developed. However, recently, the 1427 - 1518 MHz band has been opened for cellular services, so now there is a need for a base station antenna with an array of radiating elements that can operate across the entire 1427 - 2690 MHz band. Unfortunately, designing an array of radiating elements that will operate across this entire frequency range and have a suitable azimuth beamwidth at both the lower and upper ends of the operating frequency range is a significant challenge.

[0024] According to an embodiment of the present invention, there is provided a base station antenna having two or more arrays of radiating elements, where the arrays share one or more radiating elements. The (one or more) shared radiating elements can be used to reduce the azimuth beamwidth of one or both of the arrays, where the amount of reduction in the azimuth beamwidth depends on the frequency. Specifically, the reduction in the azimuth beamwidth can be relatively large in the lower part of the operating band and relatively small (or non - existent) in the upper part of the operating band. Thus, the (one or more) shared radiating elements can be used to counteract the natural tendency for the azimuth beamwidth to increase as the frequency decreases, thereby allowing the antenna beam to vary less with frequency. Thus, a base station antenna according to an embodiment of the present invention can include one or more linear arrays that can be used to support cellular services across any part of the entire 1427 - 2690 MHz band while having a suitable azimuth beamwidth across the entire band. Moreover, although the following disclosure will focus on a base station antenna with a mid band array operating in the 1427 - 2690 MHz band (or a portion thereof), it will be recognized that these same techniques can be used in, for example, low band or high band arrays to extend the operating band of these arrays and / or reduce the amount of variation in the azimuth beamwidth over the operating frequency range.

[0025] A base station antenna according to an embodiment of the present invention may share a radiation element of a first linear array with an adjacent second linear array. The shared radiation element is horizontally offset with respect to the second linear array and can thus be used to narrow the azimuth beamwidth of the second linear array. The shared radiation element can be coupled to a feed network for the second linear array through a frequency-dependent circuit element (such as a duplexer) such that the shared radiation element will substantially contribute to the antenna beam formed by the second array only for RF signals in a selected (usually lower) frequency sub-band. By sharing one or more radiation elements of the first array with the second array (but only for certain frequency sub-bands), the azimuth beamwidth of the antenna beam formed by the second array can vary less with frequency, and thus the base station antenna can form an antenna beam with a suitable shape across the entire 1427 - 2690 MHz (or other) frequency band.

[0026] In some embodiments of the present invention, a base station antenna is provided, which includes: a first radiation element array coupled to a first RF port through a first feed network, a second radiation element array coupled to a second RF port through a second feed network, and a first circuit element and a second circuit element. The first circuit element has a first port coupled to the first feed network, a second port coupled to a first port of the second circuit element, and a third port coupled to a first radiation element in the first radiation element array. The second circuit element has a second port coupled to a first radiation element in the second radiation element array and a third port coupled to the second feed network. The first circuit element may include, for example, a duplexer. The second circuit element may include, for example, a duplexer or a low-pass or band-pass filter.

[0027] In other embodiments, a base station antenna is provided, which includes: a first plurality of radiation elements coupled to a first RF port through a first feed network, wherein the first plurality of radiation elements are arranged in a first column and form a first radiation element array, and a second plurality of radiation elements coupled to a second RF port through a second feed network, wherein the second plurality of radiation elements are arranged in a second column. A first radiation element among the radiation elements in the first column is also coupled to the second RF port through the second feed network, and the radiation elements in the second column and the first radiation element among the radiation elements in the first column include a second radiation element array. Each of the above base station antennas may include a second radiation element array, which includes a first column of radiation elements and one or more horizontally offset "shared" radiation elements, and these "shared" radiation elements are part of the second radiation element array and part of the first radiation element array.

[0028] Base station antennas including antenna arrays have been previously proposed. These antenna arrays include a linear array of radiating elements plus one or more additional radiating elements horizontally offset from the linear array. Such arrays have typically been used to narrow the width of the antenna, as the horizontally offset radiating elements are used to narrow the azimuth beamwidth of the array, thereby allowing the use of smaller radiating elements while still achieving, for example, a 65° azimuth HPBW. Figures 2A - 2C is a schematic diagram of three base station antennas, each base station antenna including two arrays of radiating elements, where each array includes a linear array of radiating elements plus horizontally offset radiating elements.

[0029] First referring to Figure 2A , a conventional base station antenna 30 is depicted. The base station antenna 30 includes first and second columns 32-1, 32-2 of radiating elements 36. Except that (1) the base station antenna 30 includes fewer radiating elements 36 (and thus has a wider elevation HPBW) and (2) the radiating elements 36 are grouped differently to form two arrays 34-1, 34-2, the base station antenna 30 can be identical to the base station antenna 10 of Figure 1 . To help highlight which radiating elements 36 form each array 34-1, 34-2, polygons have been drawn around each array 34. The first array 34-1 includes the bottom five radiating elements 36 in the left column 32-1 and the bottom radiating element 36 in the right column 32-2, while the second array 34-2 includes the top five radiating elements 36 in the right column 32-2 and the top radiating element 36 in the left column 32-1. Thus, the first array 34-1 has an L shape, while the second array 34-2 has an upside-down L shape. Since each array 34-1, 34-2 includes radiating elements 36 located in opposite columns 32-2, 32-1 respectively, the horizontal aperture of each array 34-1, 34-2 increases and the azimuth beamwidth decreases accordingly. However, a disadvantage of this design is that it requires adding additional radiating elements 36 to each column 32-1, 32-2 (to allow one row of each array to include two radiating elements 36), which increases the length and cost of the antenna 30. And it does not provide any reduction in the elevation beamwidth and / or any significant increase in the gain of the antenna 30.

[0030] Figure 2Bis a schematic front view of a conventional base station antenna 40, which increases the horizontal aperture without adding additional radiating elements in each column. The base station antenna 40 includes two columns 42-1, 42-2 of radiating elements 46, which form the first and second so-called "Y-shaped" arrays 44-1, 44-2 (note that each array 44 is one radiating element short of a true "Y shape"). In addition to the base station antenna 40 including fewer radiating elements 46 and the bottom radiating elements 46 in each column 42-1, 42-2 being switched to be part of the arrays 44 formed by the remaining radiating elements 46 in the opposite columns 42-1, 42-2, the base station antenna 40 is similar to Figure 1 the base station antenna 10. Since each array 44-1, 44-2 includes radiating elements 46 located in opposite columns 42-1, 42-2, the horizontal aperture of each array 44-1, 44-2 is increased and the azimuth beamwidth is correspondingly reduced. Moreover, the base station antenna 40 does not include two radiating elements 46 in any row, so it does not suffer from the cost and size drawbacks associated with the base station antenna 30. However, a drawback of the design of the base station antenna 40 is that the physical distance between the bottom two radiating elements 46 in each array 44-1, 44-2 is increased (because the physical distance is taken along the diagonal rather than simply being the vertical distance between two radiating elements 46), and this results in off-axis grating lobes in the resulting radiation pattern formed by the first and second arrays 44-1, 44-2. These grating lobes reduce the gain of the antenna 40 and may also cause interference with adjacent base stations.

[0031] Figure 2C is a schematic front view of another conventional base station antenna 50, which has an array with an increased horizontal aperture. The base station antenna 50 is disclosed in U.S. Patent No. 8,416,142 granted to . As shown in Figure 2CAs shown in the figure, the base station antenna 50 includes first and second columns 52-1, 52-2 of dual-polarized cross-dipole radiation elements 56. The radiation elements 56 in the left column 52-1 are part of the first array 54, and the radiation elements 56 in the right column 52-2 are part of the second array 54-2. The antenna 50 also includes first and second centrally located radiation elements 58-1, 58-2, which can be designed exactly the same as the radiation elements 56. One dipole radiator of each of the centrally located radiation elements 58-1, 58-2 is part of the first array 54-1, and the other dipole radiator of each of the centrally located radiation elements 58-1, 58-2 is part of the second array 54-2. Thus, the first array 54-1 includes six dipole radiators for each polarization (i.e., five dipole radiators at each polarization in the radiation elements included in the first column 52-1, the +45° dipole radiator of the centrally located radiation element 58-1, and the -45° dipole radiator of the centrally located radiation element 58-2). Similarly, the second array 54-2 includes six dipole radiators for each polarization (i.e., five dipole radiators at each polarization in the radiation elements included in the second column 52-2, the -45° dipole radiator of the centrally located radiation element 58-1, and the +45° dipole radiator of the centrally located radiation element 58-2). The centrally located radiation elements 58-1, 58-2 are used to narrow the azimuth beamwidth by increasing the horizontal aperture of each of the arrays 54-1, 54-2, thereby allowing the size of the individual radiation elements 56, 58 to be reduced.

[0032] Embodiments of the present invention will now be discussed in more detail with reference to the remaining figures.

[0033] Figure 3A is a schematic front view of a base station antenna 100 according to an embodiment of the present invention. Figure 3B is illustrated for Figure 3A the feed network of the base station antenna 100.

[0034] As Figure 3A shown, the base station antenna 100 includes a plurality of radiation elements 114, 116, which are mounted to extend forward from a reflector 110. The base station antenna 100 also includes first to fourth RF ports 120-1 to 120-4. The radiation elements 114, 116 are mounted to form first and second vertically extending columns 130-1, 130-2 of radiation elements 120. The radiation elements 114-1 to 114-9 and the radiation elements 116-12 and 116-13 form a first array 140-1 of radiation elements (the array 140-1 is in Figure 3Bis shown in the dashed box). The radiating elements 116-1 to 116-13 form a second array 140-2 of radiating elements (array 140-2 is shown in Figure 3B the solid box). As Figure 3A shown, the first array 140-1 is a linear array of vertically extending radiating elements, and the second array 140-2 is a generally "L-shaped" array of radiating elements. As Figure 3A shown, the radiating elements 116-12 and 116-13 are shared radiating elements and are part of both the first array 140-1 and the second array 140-2.

[0035] Each of the radiating elements 114, 116 may include, for example, a dual-polarized tilted -45° / +45° cross-dipole radiating element. However, embodiments of the present invention are not limited to such radiating elements, and it will be recognized that other radiating elements (such as single-polarized dipole radiating elements, single-polarized and / or dual-polarized patch radiating elements, box dipole radiating elements, loop radiating elements, etc.) may be used instead of Figure 3A the dual-polarized tilted -45° / 45° cross-dipole radiating elements 114, 116 schematically shown using a large X (the radiating element 114 is shown using a dashed X to more clearly distinguish the two different types of radiating elements). It will also be recognized that the same type of radiating element may be used to implement the radiating element 114 and the radiating element 116, or a first type of radiating element may be used to implement the radiating element 114, and a second different type of radiating element may be used to implement the radiating element 116. In some embodiments, the radiating element 116 may be designed to operate in a first frequency range (e.g., the 1427 - 2690 MHz band), while the radiating element 114 may be designed to operate only in a portion of the first frequency range that is at the higher end of the first frequency range (e.g., the 1695 - 2690 MHz band). In such embodiments, it may be possible to use smaller and less expensive radiating elements to implement the radiating element 114 (compared to the radiating element 116).

[0036] Although a total of nine radiating elements 114 and a total of thirteen radiating elements 116 are in Figure 3Ashown, it will be appreciated that any suitable number of radiating elements 114, 116 may be included in the base station antenna 100. Also, the first and second columns 130-1, 130-2 do not need to include the same number of radiating elements, but in many cases it will be advantageous for the two columns 130 to include the same number of radiating elements. The number of radiating elements 114, 116 included in each column 130 may be selected, for example, to meet specified gain and / or elevation beamwidth requirements. Also, although the base station antenna 100 is shown as having a total of two arrays 140 of radiating elements, it will be appreciated that additional arrays of radiating elements (not shown) may be included on the antenna 100. For example, in some embodiments, one or more arrays of low-band radiating elements, one or more arrays of high-band radiating elements, and / or one or more additional arrays of mid-band radiating elements may be included.

[0037] In Figure 3A , the base station antenna 100 is shown as including two shared radiating elements 116-12, 116-13, which are located at the bottom of the first column 130-1 of radiating elements. However, it will be appreciated that embodiments of the present invention are not limited thereto. In other embodiments, a single shared radiating element or more than two shared radiating elements may be included in the antenna 100. For example, perhaps only the bottom radiating element 116-12 in the first column 130-1 is the shared radiating element. Similarly, instead of sharing one or more radiating elements located at the bottom of the column 130, one or more radiating elements 116 located at the top and / or middle portion of the column 130 may be shared between the first and second arrays 140-1, 140-2. When multiple shared radiating elements are provided, these shared radiating elements may or may not be adjacent to each other in the column 130.

[0038] Figure 3B is Figure 3A a schematic block diagram of the base station antenna 100, which schematically illustrates two of the feed networks 150 of the base station antenna 100. As Figure 3B shown, the feed network 150-1 is used to transfer RF signals between the first RF port 120-1 and the radiating elements 114-1 to 114-9 and 116-12 and 116-13 included in the first array 140-1, while the feed network 150-2 is used to transfer RF signals between the second RF port 120-2 and the radiating elements 116-1 to 116-13 included in the second array 140-2. In each case, the RF signals are transferred to the -45° radiators of the radiating elements 114, 116. In Figure 3BIn [the figure], only the feed networks 150-1 and 150-2 for the -45° RF ports 120-1 and 120-2 are shown, and the feed network 150 for the +45° RF ports 120-3 and 120-4 is omitted to simplify the drawing. It will be appreciated that the feed network 150 for the +45° RF ports 120-3 and 120-4 can be identical to the feed networks 150-1 and 150-2, respectively, except that the feed network 150 for the +45° RF ports 120-3 and 120-4 is connected to the +45° dipole radiators of the radiating elements 114 and 116 in the arrays 140-1 and 140-2, while the feed networks 150-1 and 150-2 are connected to the -45° dipole radiators of the radiating elements 114 and 116.

[0039] In the following description, various ports of the phase shifter 152 and other circuit elements may be referred to as "input ports" or "output ports". The "input" and "output" labels are made assuming that the RF signal to be transmitted by the base station antenna 100 ("transmitted RF signal") is passing through one of the feed networks 150. It will be appreciated that due to the two-way nature of the RF signal passing through the base station antenna 100, for the RF signal received by the base station antenna 100, each "output port" will operate as an input port, and each "input port" will operate as an output port.

[0040] The first feed network 150-1 includes a first phase shifter assembly 152-1 having an input end coupled to the first RF port 120-1 and five output ends 154. Each phase shifter assembly 152 may include a power splitter / combiner and a phase shifter (not shown separately). The power splitter / combiner may be a component that divides an RF transmitted signal into multiple sub-components and combines multiple sub-components of a received RF signal into a single combined RF signal. The phase shifter may be a component that imparts a phase taper to the respective components of the transmitted RF signal and the received RF signal. The phase shifter may be an adjustable phase shifter that can be remotely controlled to vary the amount of phase taper applied to the transmitted and received RF signals in order to impart a desired amount of electrical downtilt to the antenna beam. Suitable phase shifter assemblies are disclosed, for example, in U.S. Patent Publication No. 2017 / 0365923, the entire content of which is incorporated herein by reference.

[0041] The RF signal input at RF port 120-1 enters the phase shifter assembly 152-1 at the input port of the phase shifter assembly 152-1 and is divided into five sub-components by the power splitter / combiner integrated in the phase shifter assembly 152-1. The phase shifter assembly 152-1 can be adjusted to apply a phase taper to the five sub-components of the RF signal so as to apply a desired amount of electrical downtilt to the elevation angle of the antenna beam formed by the first array 140-1. Each output terminal 154 of the phase shifter assembly 152-1 is coupled to a sub-array 112 of the radiating elements 114, 116. Specifically, the first output terminal 154 is coupled to a first sub-array 112-1 including radiating elements 114-1 to 114-3, the second output terminal 154 is coupled to a second sub-array 112-2 including radiating elements 114-4 and 114-5, the third output terminal 154 is coupled to a third sub-array 112-3 including radiating elements 114-6 and 114-7, the fourth output terminal 154 is coupled to a fourth sub-array 112-4 including radiating elements 114-8 and 114-9, and the fifth output terminal 154 is coupled to a fifth sub-array 112-5 including radiating elements 116-12 and 116-13. As Figure 3B further shown, the fifth output terminal 154 of the phase shifter assembly 150-1 is coupled to the fifth sub-array 112-5 through a first circuit element 160. The first circuit element 160 can be a frequency selective device such as, for example, a duplexer or other multiplexer.

[0042] The second feed network 150-2 includes a second phase shifter assembly 152-2 having an input terminal coupled to the second RF port 120-2 and five output terminals 154. The RF signal input at the RF port 120-2 enters the phase shifter assembly 152-2 at the input port of the phase shifter assembly 152-2 and is divided into five sub-components by a power splitter / combiner integrated into the phase shifter assembly 152-2. The phase shifter assembly 152-2 can be adjusted to apply a phase taper to the five sub-components of the RF signal so as to electronically downtilt the elevation angle of the antenna beam formed by the second array 140-2. Each output terminal 154 of the phase shifter assembly 152-2 is coupled to a corresponding sub-array 112 of the radiating elements 116. Specifically, the first output terminal 154 is coupled to the sixth sub-array 112-6 including the radiating elements 116-1 to 116-3, the second output terminal 154 is coupled to the seventh sub-array 112-7 including the radiating elements 116-4 and 116-5, the third output terminal 154 is coupled to the eighth sub-array 112-8 including the radiating elements 116-6 and 116-7, the fourth output terminal 154 is coupled to the ninth sub-array 112-9 including the radiating elements 116-8 and 116-9, and the tenth output terminal 154 is coupled to the tenth sub-array 112-10 including the radiating elements 116-10 and 116-11 and is also coupled to the fifth sub-array 112-5 including the radiating elements 116-12 and 116-13. As Figure 3B shown, the fifth output terminal 154 of the phase shifter assembly 152-2 is coupled to the fifth and tenth sub-arrays 112-5, 112-10 through a second circuit element 170. The second circuit element 170 can also be a frequency selective device, such as, for example, a duplexer or other multiplexer or power splitter, which has a filter, such as a low-pass or band-pass filter, on one of its output branches.

[0043] The first circuit element 160 and the second circuit element 170 can be configured to allow the radiating elements 116-12 and 116-13 to be shared by the first and second arrays 140-1, 140-2 in a frequency-selective manner. In one example embodiment, the first circuit element 160 can be a duplexer having first and second frequency-selective ports 162-1, 162-2 and a "common" port 162-3. As discussed above, the first array 140-1 of the base station antenna 100 is designed to transmit and receive RF signals in the 1695 - 2690 MHz band, while the second array 140-2 is designed to transmit and receive RF signals in the 1427 - 1518 MHz and 1695 - 2690 MHz bands. Accordingly, the first frequency-selective port 162-1 of the duplexer 160 is configured to pass RF signals in the 1695 - 2690 MHz band, but block RF signals in the 1427 - 1518 MHz band. The second frequency-selective port 162-2 of the duplexer 160 is configured to pass RF signals in the 1427 - 1518 MHz band, but block RF signals in the 1695 - 2690 MHz band. The "common" port 162-3 is configured to pass RF signals in both the 1427 - 1518 MHz and 1695 - 2690 MHz bands.

[0044] In some embodiments, the second circuit element 170 can similarly be implemented as a duplexer having first and second frequency-selective ports 172-1, 172-2 and a "common" port 172-3. The first frequency-selective port 172-1 of the duplexer 170 is configured to pass RF signals in the 1427 - 1518 MHz band, but block RF signals in the 1695 - 2690 MHz band. The second frequency-selective port 172-2 of the duplexer 170 is configured to pass RF signals in the 1695 - 2690 MHz band, but block RF signals in the 1427 - 1518 MHz band. The "common" port 172-3 of the duplexer 170 is configured to pass RF signals in both the 1427 - 1518 MHz and 1695 - 2690 MHz bands.

[0045] The base station antenna 100 can operate as follows. A first RF signal within the 1695 - 2690 MHz frequency band can be input at RF port 120-1. The first RF signal is divided into five sub-components and phase-shifted by the phase shifter assembly 152-1. The first to fourth sub-components of the RF signal are transmitted to the corresponding sub-arrays 112-1 to 112-4, where the sub-components are radiated by the radiating elements 114-1 to 114-9. The fifth sub-component is transmitted to port 162-1 of the duplexer 160. Since the sub-component is within the 1695 - 2690 MHz "passband" of port 162-1, the fifth sub-component will be transmitted to the common port 162-3 of the duplexer 160 and from there to the fifth sub-array 112-5, where the fifth sub-component of the RF signal is radiated by the radiating elements 116-12 and 116-13. Since the fifth sub-component is not within the 1427 - 1518 MHz "passband" of port 162-2, the fifth sub-component will not be transmitted to the second circuit element 170 or to any of the radiating elements in the second column 130-2 of the radiating elements. Thus, the first RF signal input at RF port 120-1 is transmitted to the first array 140-1 of radiating elements, which first array 140-1 includes the radiating elements 114-1 to 114-9 and the radiating elements 116-12 and 116-13. The first array 140-1 is a linear array of radiating elements, and the duplexer 160 has no effect on the RF signal entering at the first RF port 120-1 other than causing a small insertion loss.

[0046] A second RF signal can be input at RF port 120-2. As discussed above, the second RF signal can be either within the 1427 - 1518 MHz frequency band or within the 1695 - 2669 MHz frequency band. The second RF signal is divided into five sub-components and phase-shifted by the phase shifter assembly 152-2. The first to fourth sub-components of the second RF signal are transmitted to the corresponding sub-arrays 112-6 to 112-9, where the sub-components are radiated by the radiating elements 116-1 to 116-9. The fifth sub-component is transmitted to the common port 172-3 of the duplexer 170. The operation of the duplexer 170 will vary depending on the frequency of the second RF signal.

[0047] Specifically, if the second RF signal input at RF port 120-2 is in the 1695-2690 MHz band, then the fifth sub-component of this signal will be passed to the frequency-selective port 172-2 of the duplexer 170, which has a passband of 1695-2690 MHz. Thus, the fifth sub-component of the second RF signal will pass through the duplexer 170 to the tenth sub-array 112-10 (radiating elements 116-10 and 116-11) of the radiating elements. Since the sub-component is not within the 1427-1518 MHz passband of the frequency-selective port 172-1, the fifth sub-component will not be passed to the first duplexer 160. Thus, the signal in the 1695-2690 MHz band input at RF port 120-2 will be radiated only by the radiating elements 116-1 to 116-11 of the second array 140-2, and thus the second array 140-2 will operate as a second linear array of radiating elements.

[0048] If the second RF signal input at RF port 120-2 is in the 1427-1518 MHz band, then the fifth sub-component of this signal will also be passed through the common port 172-3 of the duplexer 170. Since the fifth sub-component is not within the 1695-2690 MHz passband of the frequency-selective port 172-2, the sub-component will not be passed to the tenth sub-array 112-10 (radiating elements 116-10 and 116-11) of the radiating elements. Since the fifth sub-component is within the 1427-1518 MHz passband of the frequency-selective port 172-1, the fifth sub-component will be passed to the frequency-selective port 162-2 of the first duplexer 160 and will then be passed through the first duplexer 160 to the fifth sub-array 112-5 of the radiating elements. Thus, the signal in the 1427-1518 MHz band input at RF port 120-2 will be radiated by the radiating elements 116-1 to 116-9 and 116-12 and 116-13 (and not by the radiating elements 116-10 and 116-11) of the second array 140-2. Thus, when both the first and second circuit elements 160, 170 are implemented as duplexers, depending on the frequency of the input signal, the second array 140-2 will operate as a linear array or as a so-called Y-shaped array.

[0049] Thus, in each case, the second RF signal input at RF port 120-2 will be radiated by eleven of the radiating elements 116. However, the difference is that if the RF signal is at the higher 1695-2690 MHz frequency, then the radiating elements used to generate the antenna beam are all in a single vertically deployed column 130-2, so the second array 140-2 is not used to contract the azimuth beamwidth of the generated antenna beam. Instead, if the RF signal is in the lower 1427-1518 MHz frequency range, then two of the radiating elements 116 used to generate the antenna beam (radiating elements 116-12 and 116-13) are horizontally offset relative to the remaining nine radiating elements (116-1 to 116-9), and this horizontal offset is used to contract the azimuth beamwidth of the generated antenna beam. The amount of azimuth beamwidth contraction can depend on (1) the horizontal distance between the two columns 130-1, 130-2, and (2) the ratio of the power of the sub-component of the second RF signal delivered to radiating elements 116-1 to 116-9 to the power of the fifth sub-component of the second RF signal delivered to radiating elements 116-12 and 116-13.

[0050] As indicated by the discussion above, the base station antenna 100 can be configured to reduce the azimuth beamwidth of an RF signal input at RF port 120-2 that is in the lower 1427-1518 MHz band, without performing any such reduction on the azimuth beamwidth of an RF signal input at RF port 120-2 that is in the higher 1695-2690 MHz band. This approach is used to counteract the inherent broadening of the azimuth beamwidth that occurs as the frequency decreases, in order to provide an array of radiating elements 140-2 that exhibits less variation in azimuth beamwidth over the ultra-wide 1427-2690 MHz band.

[0051] In other embodiments, the second circuit element 170 can alternatively be implemented as a power splitter that has a low-pass filter (or band-pass filter) at one of the "output" ports of the power splitter (i.e., port 172-1). The low-pass (or band-pass) filter is configured to pass RF signals in at least the 1427-1518 MHz band while blocking RF signals in the 1695-2690 MHz band. In this embodiment, the second circuit element has two common ports (ports 172-2 and 172-3) that pass signals over the entire 1427-2690 MHz frequency range and one frequency-selective port (port 172-1). The frequency-selective port 172-1 can be designed to pass only signals in the 1427-1518 MHz band, or it can be designed to have a "soft" roll-off such that as the frequency increases above approximately 1518 Hz, the frequency-selective port 172-1 allows less power to pass.

[0052] When the second circuit element 170 is implemented as a power splitter with a filter on one port, the base station antenna 100 can operate as follows. A first RF signal in the 1695 - 2690 MHz band can be input at RF port 120 - 1. This first RF signal is transferred to the first array 140 - 1 of radiating elements including radiating elements 114 - 1 to 114 - 9 in exactly the same manner as in the embodiment above where the second circuit element 170 was implemented as a duplexer. Thus, its further description will be omitted.

[0053] A second RF signal in the 1427 - 1518 MHz band or the 1695 - 2690 MHz band can be input at RF port 120 - 2. The second RF signal is divided into five sub - components and phase - shifted by the phase shifter assembly 152 - 2. The first to fourth sub - components of the RF signal are transferred to the corresponding sub - arrays 112 - 6 to 112 - 9, where these sub - components are radiated by the radiating elements 116 - 1 to 116 - 9. The fifth sub - component is transferred to the common port 172 - 3 of the power splitter / low - pass filter 170. Again, the operation of the second circuit element 170 will vary depending on the frequency of the second RF signal.

[0054] Specifically, if the signal input at RF port 120 - 2 is in the 1695 - 2690 MHz band, then the fifth sub - component of this signal will be transferred from the common port 172 - 3 of the power splitter / filter 170 to the common port 172 - 2 and supplied to the tenth sub - array 112 - 10 (radiating elements 116 - 10 and 116 - 11) of the radiating elements. The low - frequency band (or pass - band) filter on the frequency - selective port 172 - 1 blocks the RF signal (since it is in the higher 1695 - 2690 MHz band), and thus, in response to an RF signal in the 1695 - 2690 MHz band, the second array 140 - 2 will operate as a linear array including radiating elements 116 - 1 to 116 - 11.

[0055] If the RF signal input at RF port 120-2 is in the 1427-1518 MHz band, then the fifth sub-component of this signal will also be passed through the common port 172-3 of the power splitter / filter 170. Since the sub-component is within the 1427-1518 MHz passband of the frequency selective port 172-1, this sub-component will be passed to the second port 162-2 of the duplexer 160 and then will be passed through the duplexer 160 to the fifth sub-array 112-5 (i.e., to the radiating elements 116-12 and 116-13). Also, since the second port 172-2 of the power splitter / filter 170 is a common port, the signal will also be passed to the tenth sub-array 112-10 of the radiating elements (radiating elements 116-10 and 116-11). The power splitter included in the power splitter / filter 170 can be set to equally or unequally split the power of the fifth sub-component of the RF signal depending on the desired narrowing amount of the azimuth beam width. Thus, when the second circuit element 170 is implemented as the power splitter / filter 170, in response to an RF signal in the 1427-1518 MHz frequency range, the second array 140-2 will operate as an L-shaped array including the radiating elements 116-1 to 116-13.

[0056] As indicated by the above discussion, depending on which implementation is selected for the second circuit element 170, the second array 140-2 will operate differently. In fact, the duplexer implementation of the second circuit element 170 results in a Y-shaped second array 140-2 for RF signals in the 1427-1518 MHz band, while the power splitter / filter implementation of the second circuit element 170 results in an L-shaped second array 140-2 for RF signals in the 1427-1518 MHz band. Under both of these implementations, in response to a signal in the 1695-2690 MHz band, the second array 140-2 operates as a linear array.

[0057] Figure 4A is a front view of the printed circuit board-based duplexer 200, which can be used to implement any one or both of the first circuit element 160 and / or the second circuit element 170 of the base station antenna 100 of Figures 3A - 3B the exemplary embodiment of the present invention.

[0058] As Figure 4AAs shown, the duplexer 200 is implemented on a microstrip printed circuit board 210. The microstrip printed circuit board 210 may include a dielectric substrate 212 having a ground plane metallization layer (not shown) covering the back of the substrate and a metal "trace" pattern 214 on the front of the substrate 212. The traces of the trace pattern 214 form microstrip transmission line segments and resonant stubs. The metal trace pattern 214 includes three "ports", which represent locations where RF signals can be input and / or output from the duplexer 200. These ports include a first common port 220-1 and a pair of frequency-selective ports 220-2, 220-3. A first trace defines a first microstrip transmission line segment 230-1 that connects port 220-1 to port 220-2, and a second trace defines a second microstrip transmission line segment 230-2 that connects port 220-1 to port 220-3. The resonant stubs 216 are designed to form filters along each microstrip transmission line segment 230-1, 230-2 that pass RF signals in certain frequency bands while suppressing RF signals in other frequency bands.

[0059] Figure 4B is a graph showing Figure 4A the simulated response of the duplexer 200 shown. Figure 4B In the curve 240-1 in, the amplitude as a function of frequency of the signal output at port 220-2 in response to an RF signal input at port 220-1 is shown, while the curve 240-2 shows the amplitude as a function of frequency of the signal output at port 220-3 in response to an RF signal input at port 220-1. As Figure 4B shown by the curve 240-2 in, signals in the 1427 - 1518 MHz frequency band input to the duplexer 200 at port 220-1 reach port 220-3 with little attenuation, while signals in the 1695 - 2690 MHz frequency range are substantially or completely blocked at port 220-3. Conversely, as Figure 4B shown by the curve 240-1 in, signals in the 1695 - 2690 MHz frequency band input to the duplexer 200 at port 220-1 reach port 220-2 with little attenuation, while signals in the 1427 - 1518 MHz frequency range are substantially or completely blocked at port 220-2.

[0060] Figure 5A is a front view of a printed circuit board-based power splitter 250 that has a low-pass filter at one of its output terminals and can be used to implement the Figures 3A - 3B second circuit element 170 of the base station antenna 100 in an exemplary embodiment of the present invention. Figure 5B is a graph showing Figure 5AGraph of the simulated response of the power splitter / low-pass filter circuit 250.

[0061] As Figure 5A shown, the power splitter / low-pass filter circuit 250 is implemented on a microstrip printed circuit board 260. The power splitter / low-pass filter circuit 250 includes a power splitter 252 and a low-pass filter 254. The microstrip printed circuit board 260 may include a dielectric substrate 262 having a ground plane metallization layer (not shown) covering the back side of the substrate and a metal "trace" pattern 264 on the front side of the substrate 262. The traces of the trace pattern 264 form microstrip transmission line segments and resonant stubs 266. The metal trace pattern 264 includes three "ports", which represent locations where RF signals can be input and / or output from the power splitter / low-pass filter circuit 250. These ports include a first common port and a second common port 270-1, 270-2 that respectively form the input port and the first output port of the power splitter 252, and a second output port 270-3 of the power splitter 252, and the second output port 270-3 includes a low-pass filter 254 that makes the output port 270-3 a frequency-selective port. A first trace defines a first microstrip transmission line segment 280-1 that connects port 270-1 to port 270-2, and a second trace defines a second microstrip transmission line segment 280-2 that connects port 270-1 to port 270-3. The resonant stub 266 forms the low-pass filter 254.

[0062] Figure 5B is a graph showing Figure the simulated response of the power splitter / low-pass filter circuit 250. ​ Curve 290-1 in ​ shows the magnitude as a function of frequency of the signal output at port 270-2 in response to an RF signal input at port 270-1, while curve 290-2 shows the magnitude as a function of frequency of the signal output at port 270-3 in response to an RF signal input at port 270-1. As

[0063] ​ The shape of curve 290-2 in can be changed by increasing or decreasing the number of resonant stubs 266 included in low-pass filter 254. If additional resonant stubs 266 are added, the power at port 270-3 decreases more rapidly as the frequency increases, while if fewer resonant stubs 266 are included, the power at port 270-3 decreases more slowly as the frequency increases. Thus, the design of filter 254 can be used to further adjust the azimuth HPBW as a function of frequency.

[0064] ​ Yes, for ​ the second array 140-2 of radiating elements of base station antenna 100 of ​ when using ​ the duplexer 200 of as the first circuit element 160 and using ​ the power splitter / low-pass filter circuit 250 of as the second circuit element 170, a graph (curve 300) of the simulated azimuth HPBW as a function of frequency. For purposes of comparison,

[0065] As ​ shown, the azimuth HPBW (curve 310) for a linear array of conventional radiating elements varies between a low value of approximately 55.5° and a high value of approximately 88°, with a total variation of more than 32°. This amount of variation is generally unacceptable because the large azimuth HPBW in the lower part of the frequency band results in low gain values in the sector served by the linear array and high interference levels in adjacent sectors. As shown by curve 300, the second array 140-2 of base station antenna 100 according to an embodiment of the present invention has an azimuth HPBW that varies between a low value of approximately 50° and a high value of approximately 75°, with a total variation of only 19°, which is more than 13° less than the variation seen for a conventional linear array.

[0066] ​ Yes, for ​ the duplexer 200 of as the first circuit element 160 and using ​ the power splitter / low-pass filter circuit 250 of as the second circuit element 170 to implement ​ a graph (curve 320) of the simulated gain as a function of frequency for the second array 140-2 of radiating elements of base station antenna 100 of ​ For purposes of comparison, ​As shown, the gain of the second array 140-2 of the base station antenna 100 is higher than that of a conventional linear array over the entire frequency range. Compared with the conventional array, each of the first and second circuit elements 160, 170 introduces insertion loss, which reduces the gain of the second linear array 140-2. However, the narrowing of the azimuth beamwidth, especially at the lower end of the frequency range, results in a gain increase that more than offsets the insertion loss. Therefore, the base station antenna 100 according to an embodiment of the present invention can also exhibit improved gain performance.

[0067] ​ Yes, for use ​ of the duplexer 200 as both the first circuit element 160 and the second circuit element 170 ​ of the second array 140-2 of the radiating elements of the base station antenna 100, a graph (curve 340) of the simulated azimuth HPBW as a function of frequency. For comparison purposes, ​ also includes a graph (curve 350) of the simulated azimuth HPBW of a comparable single-column linear array of radiating elements.

[0068] As ​ shown, the second array 140-2 of the base station antenna 100 according to an embodiment of the present invention has an azimuth HPBW that varies between a low value of approximately 56° and a high value of approximately 75°, with a total variation of only 19°, which is more than 13° less than the variation seen for a conventional linear array.

[0069] ​ is a schematic front view of a base station antenna 400 according to a further embodiment of the present invention. ​ is illustrated for ​ the base station antenna 400 of two feed networks in the feed network 450.

[0070] As ​ shown, the base station antenna 400 is similar to ​ the base station antenna 100. However, the base station antenna 400 differs from the base station antenna 100 in four aspects. First, the base station antenna 400 includes a third circuit element 460 that can be identical to the first circuit element 160. Second, the base station antenna 400 includes a fourth circuit element 470 that can be identical to the second circuit element 170. Third, all the radiating elements in the base station antenna 400 are implemented as radiating elements that operate over the entire 1427 - 2690 MHz frequency band and are thus labeled as radiating elements 116-1 to 116-22 in ​ . Fourth, the first array 440-1 of the base station antenna 400 also includes radiating elements 116-10 and 116-11 located in the second column 130-2 of the radiating elements.

[0071] As can be seen from ​ the figure, in base station antenna 400, each of the arrays 440-1, 440-2 has exactly the same configuration, using a pair of additional circuits to reduce the azimuth beam width in the lower part of the frequency band. Except that the output terminal 172-2 of the second circuit element 170 is coupled to the tenth sub-array 112-10 through the third circuit element 460, the second feed network 450-2 and the second array 440-2 can be exactly the same as the second feed network 150-2 and the second array 140-2 of the base station antenna 100 in design and operation. In addition, except that the output terminal 472-2 of the fourth circuit element 470 is coupled to the fifth sub-array 112-5 through the first circuit element 160, the first feed network 450-1 and the first array 440-1 can also be exactly the same as the second feed network 150-2 and the second array 140-2 of the base station antenna 100 in design and operation. Since both the first and second arrays 440-1, 440-2 of the base station antenna 400 will operate in the same manner as the second array 140-2 of the base station antenna 100, ​ further description thereof will be omitted.

[0072] [[ID= eight]] ​ FIG. is a schematic front view of a base station antenna 500 according to some further embodiments of the present invention. The base station antenna 500 includes three columns 530-1 to 530-3 of radiating elements, and these three columns form three arrays 540-1 to 540-3 of radiating elements. ​ FIG. is a schematic block diagram of the feed networks 550-1 to 550-3 of the base station antenna 500 for ​ . The base station antenna 500 is very similar to the base station antenna 100 discussed above, except that the base station antenna 500 further includes a third column 530-3 of radiating elements and shares the radiating elements at the top of the first column 530-1 to provide a third array 540-3 with frequency selective characteristics.

[0073] Except that (1) the feed network 550-1 further includes an additional first circuit element 160-2 coupled between the top sub-array of the radiating elements in the column 530-1 and the phase shifter assembly 152-1, and (2) the top sub-array of the radiating elements in the column 530-1 is implemented using a wider band radiating element 116, the feed network 550-1 and the array 540-1 can be exactly the same as the feed network 150-1 and the array 140-1 of the base station antenna 100. The feed network 550-2 and the array 540-2 can be exactly the same as the feed network 150-2 and the array 140-2 of the base station antenna 100. Except for sharing the radiating elements at the top of the column 530-1, the third feed network 550-3 can be exactly the same as the feed network 550-2.

[0074] ​ FIG. 600 is a schematic block diagram of a base station antenna 600 according to a further embodiment of the present invention. The base station antenna 600 is designed to differently narrow the azimuth beamwidth for the radiation element arrays in three different sub-bands. The base station antenna 600 illustrates how the concept of using additional circuit elements such as circuit elements 160 and 170 to reduce the azimuth HPBW for the first sub-band of the operating band can be extended so that the azimuth HPBW can be reduced for multiple sub-bands, where the azimuth HPBW of each sub-band is reduced by a different amount.

[0075] As ​ shown, the base station antenna 600 is similar to the base station antenna 100, but the base station antenna 600 includes an additional first circuit element 160-2 and an additional second circuit element 170-2. In this embodiment, both the first circuit elements 160-1 and 160-2 are implemented as duplexers, and both the second circuit elements 170-1 and 170-2 are implemented as power dividers with low-pass filters, but it will be appreciated that the present invention is not limited thereto.

[0076] As ​ shown, except that (1) the first duplexer 160-1 is only coupled to the bottom radiation element 116 in the first column 130-1, (2) the first splitter / filter 170-1 is only coupled to the bottom radiation element 116 in the second column 130-2, (3) a second duplexer 160-2 is provided and coupled to the next radiation element adjacent to the bottommost radiation element 116 in the first column 130-1, and (4) a second splitter / filter 170-2 is provided and coupled to the next radiation element adjacent to the bottommost radiation element 116 in the second column 130-2, the base station antenna 600 is identical to the base station antenna 100. The second duplexer 160-2 and the second splitter / filter 170-2 are configured to allow the next radiation element adjacent to the bottommost radiation element in the first column 130-1 to be shared between the two arrays 640-1 and 640-2, but for a different frequency range compared to the bottommost radiation element in the first column 130-1.

[0077] In an exemplary embodiment, the first duplexer 160-1 may be implemented to have a frequency selective port 162-2 in the 1427-1518 MHz frequency range, a frequency selective port 162-1 in the 1695-2690 MHz frequency range, and a common port 162-3. The second duplexer 160-2 may be implemented to have a frequency selective port 164-1 in the 1695-2690 MHz frequency range, a frequency selective port 164-2 in the 1427-2200 MHz frequency range, and a common port 164-3. The first duplexer / filter 170-1 may be implemented as a power splitter having a port with a low pass filter (the low pass filter having a nominal cut-off frequency between 1518 MHz and 1695 MHz) and first and second common ports 172-2, 172-3. The second duplexer / filter 170-2 may be implemented as a power splitter having a port 174-1 with a low pass filter (the low pass filter having a nominal cut-off frequency between 2200 MHz and 2300 MHz) and first and second common ports 174-2, 174-3.

[0078] Similar to the first array 140-1 of the base station antenna 100, for RF signals at any frequency in the 1427-2690 MHz frequency range, the first array 640-1 of the radiating elements of the base station antenna 600 will operate as a linear array of radiating elements. Similar to the first array 140-2 of the base station antenna 100, for RF signals in the 2300-2690 MHz frequency range, the second array 640-2 of the radiating elements of the base station antenna 600 will operate as a linear array of eleven radiating elements 116-1 to 116-11. Similar to the second array 140-2 of the radiating elements of the base station antenna 100, for RF signals in the 1427-1518 MHz frequency range, the second array 640-2 of the radiating elements will operate as a two-column array including all eleven elements in column 130-2 and the bottom two radiating elements in column 130-1. However, the second array 640-2 of the radiating elements differs from the second array 140-2 of the radiating elements of the base station antenna 100 in that for RF signals in the 1695-2200 MHz frequency range, the second array 640-2 of the radiating elements will operate as a two-column array including all eleven elements in column 130-2 and the next radiating element adjacent to the bottom-most radiating element in column 130-1, while for such signals, the second array 140-1 of the radiating elements of the base station antenna 100 operates as a linear array. The base station antenna 600 may also reduce the variation of the azimuth HPBW across the 1427-2690 MHz band.

[0079] Accordingly, the base station antenna 600 includes first and second RF ports 120-1, 120-2 and first and second horizontally offset vertical columns 130-1, 130-2 of radiating elements. More than half of the radiating elements in the first vertical column 130-1 are part of a first array 640-1 of radiating elements, and the first array 640-1 of radiating elements is coupled to the first RF port 120-1 through a first feed network 150-1, and more than half of the radiating elements in the second vertical column 130-2 are part of a second array 640-2 of radiating elements, and the second array 640-2 of radiating elements is coupled to the second RF port 120-2 through a second feed network 150-2. For RF signals in a first frequency range (here the 2300-2690 MHz frequency range), the second array 640-2 of radiating elements includes a first number (here 0) of radiating elements in the first column 130-1, and for RF signals in a second frequency range (here the 1695-2200 MHz frequency range) below the first frequency range, the second array 640-2 of radiating elements includes a second number (here 1) of radiating elements in the first column 130-1, and the second number is greater than the first number. For RF signals in a third frequency range (here the 1427-1518 MHz frequency range) below the second frequency range, the second array 640-2 of radiating elements includes a third number (here 2) of radiating elements in the first column 130-1, and the third number is greater than the second number.

[0080] The embodiments of the present invention have been described above with reference to the accompanying drawings in which embodiments of the invention are shown. However, the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like reference numerals always denote like elements.

[0081] It will be understood that although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of the present invention, a first element may be termed a second element, and similarly, a second element may be termed a first element. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0082] It will be understood that when an element is referred to as being “on” another element, it can be “directly on” the other element or there can be intervening elements. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements. It will also be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or there can be intervening elements. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements. Other words used to describe the relationship between elements should be interpreted in a similar manner (i.e., “between” relative to “directly between”, “adjacent” relative to “directly adjacent”, etc.)

[0083] It will be understood that when used herein, the terms “comprises” and / or “comprising” specify the presence of the stated features, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, operations, elements, components, and / or groups thereof.

[0084] Aspects and elements of all of the embodiments disclosed above can be combined in any manner and / or in combination with aspects or elements of other embodiments to provide a plurality of additional embodiments.

[0085] In the drawings and the specification, typical preferred embodiments of the invention have been disclosed, and although specific terms are employed, they are used in a general and descriptive sense only and not for purposes of limitation, the scope of the invention being set forth in the following claims.

Claims

1. A base station antenna, comprising: A first radio frequency (RF) port; A second RF port; A first radiation element array coupled to the first RF port via a first feeding network; A second radiation element array coupled to the second RF port via a second feeding network; A first frequency selective circuit element; And A second frequency selective circuit element; Wherein, the first frequency selective circuit element has a first port coupled to the first feeding network, a second port coupled to the first port of the second frequency selective circuit element, and a third port coupled to the first radiation element of the first radiation element array. The second port and the third port of the first frequency selective circuit element are configured to allow RF signals in different frequency bands to pass through; and Wherein, the second frequency selective circuit element has a second port coupled to the first radiation element of the second radiation element array and a third port coupled to the second feeding network. The second port and the third port of the second frequency selective circuit element are configured to allow RF signals in different frequency bands to pass through; Wherein, the second radiation element array includes a first number of radiation elements when operating in a first frequency band, and includes a larger number of radiation elements when operating in a second frequency band.

2. The base station antenna according to claim 1, wherein, The first radiation element of the first radiation element array is also part of the second radiation element array.

3. The base station antenna according to claim 2, wherein, The second frequency selective circuit element is a power splitter, and the power splitter has a filter at a first output port of the power splitter.

4. The base station antenna according to claim 2, wherein, The first frequency selective circuit element is a duplexer.

5. The base station antenna according to claim 3, wherein, The first frequency selective circuit element is a duplexer.

6. The base station antenna according to claim 1, wherein The second radiation element array is configured to operate in a first frequency range including a first frequency band and a second frequency band, and the first radiation element array is configured to operate in a second frequency range. The second frequency range partially but not completely overlaps with the first frequency range.

7. The base station antenna according to claim 6, wherein, The second frequency selective circuit element is configured to transfer a signal input at a third RF port and in a part of the second frequency range that overlaps with the first frequency range to the first radiation element of the second radiation element array, and transfer a signal input at the third RF port and in a part of the second frequency range that does not overlap with the first frequency range to the first frequency selective circuit element.

8. The base station antenna according to claim 7, wherein, The first frequency selective circuit element is configured to transfer a signal input at the second RF port and in a part of the second frequency range that does not overlap with the first frequency range to the first radiation element of the first radiation element array.

9. The base station antenna according to claim 1, wherein, The first radiation element array is configured to operate in some or all of the frequency bands in the 1695 - 2690 MHz frequency band but not in the 1427 - 1518 MHz frequency band, while the second radiation element array is configured to operate in some or all of the frequency bands in the 1427 - 2690 MHz frequency band including at least a part of the 1427 - 1518 MHz frequency band and at least a part of the 1695 - 2690 MHz frequency band.

10. A base station antenna, comprising: A first radio frequency (RF) port; A second RF port; A first radiation element array coupled to the first RF port via a first feeding network; A second radiation element array, coupled to a second RF port via a second feed network; A first duplexer; And A second duplexer; Wherein, the first duplexer has a first port coupled to a first feed network, a second port coupled to a first port of the second duplexer, and a third port coupled to a first radiation element of a first radiation element array; and Wherein, the second duplexer has a second port coupled to a first radiation element of the second radiation element array and a third port coupled to a second feed network; Wherein, the first radiation element of the first radiation element array is also part of the second radiation element array.

11. The base station antenna according to claim 10, wherein, The first radiation element array consists of a first column of radiation elements, and wherein, the second radiation element array consists of a second column of radiation elements and one or more radiation elements in the first radiation element array, the one or more radiation elements including the first radiation element of the first radiation element array.

12. The base station antenna according to claim 11, wherein, The first column of radiation elements is horizontally offset relative to the second column of radiation elements.

13. A base station antenna, comprising: A first radio frequency (RF) port; A second RF port; A first radiation element array, coupled to the first RF port via a first feed network; A second radiation element array, coupled to the second RF port via a second feed network; A first frequency selective circuit element; A second frequency selective circuit element; A third frequency selective circuit element; And A fourth frequency selective circuit element, Wherein, the first frequency selective circuit element has a first port coupled to a second port of the fourth frequency selective circuit element, a second port coupled to a first port of the second frequency selective circuit element, and a third port coupled to a first radiation element of the first radiation element array; Wherein, the second frequency selective circuit element has a second port coupled to a first port of the third frequency selective circuit element and a third port coupled to a second feed network; Wherein, the third frequency selective circuit element has a third port coupled to a first radiation element of the second radiation element array and a second port coupled to a first port of the fourth frequency selective circuit element, Wherein, the fourth frequency selective circuit element has a third port coupled to a first feed network; and Wherein, the first radiation element of the second radiation element array is also part of the first radiation element array.

14. The base station antenna according to claim 13, wherein, The third frequency selective circuit element is a duplexer or a power splitter, the duplexer or the power splitter having a low pass filter on its first output, and the fourth frequency selective circuit element is a duplexer.

15. The base station antenna according to claim 13, wherein, The fourth frequency selective circuit element is a low pass filter.

16. The base station antenna according to claim 13, wherein, The fourth frequency selective circuit element is a duplexer.

17. A base station antenna, comprising: A first radio frequency (RF) port; A second RF port; A first plurality of radiation elements, coupled to the first RF port via a first feed network, wherein, the first plurality of radiation elements are arranged in a first column and form a first radiation element array; and A second plurality of radiating elements, coupled to a second RF port via a second feed network, wherein the second plurality of radiating elements are arranged in a second column and form a second radiating element array, and wherein the second radiating element array includes the second plurality of radiating elements in the second column and one or more radiating elements of the first plurality of radiating elements in the first column; A first frequency selective circuit element having a first port coupled to the first feed network, a second port coupled to the second feed network, and a third port coupled to a first radiating element of the radiating elements in the first column; A second frequency selective circuit element having a first port coupled to the second port of the first frequency selective circuit element, a second port coupled to a first radiating element of the radiating elements in the second column, and a third port coupled to the second feed network; Wherein the first port of the second frequency selective circuit element is configured to block signals within a portion of the operating band of at least some of the second plurality of radiating elements, and the second port of the first frequency selective circuit element is configured to block signals within a portion of the operating band of at least some of the first plurality of radiating elements.

18. The base station antenna according to claim 17, wherein, The first radiating element array is configured to operate in some or all of the frequency bands in the 1695 - 2690 MHz band but not in the 1427 - 1518 MHz band, while the second radiating element array is configured to operate in some or all of the frequency bands in the 1427 - 2690 MHz band including at least a portion of the 1427 - 1518 MHz band and at least a portion of the 1695 - 2690 MHz band.

19. The base station antenna according to claim 17, wherein, The second frequency selective circuit element is a duplexer or a power splitter having a port including a low - pass filter.

20. The base station antenna according to claim 19, wherein The first frequency selective circuit element is a duplexer.

21. The base station antenna according to claim 17, wherein, The first radiating element array is configured to operate in a first frequency range, and the second radiating element array is configured to operate in a second frequency range that only partially overlaps with the first frequency range.

22. A base station antenna, comprising: A first radio frequency (RF) port; A second RF port; A first vertical column of radiating elements; And A second vertical column of radiating elements, horizontally offset with respect to the radiating elements of the first vertical column; Wherein more than half of the radiating elements in the first vertical column and at least one radiating element in the second vertical column are part of a first radiating element array, and the first radiating element array is coupled to the first RF port via a first feed network, Wherein more than half of the radiating elements in the second vertical column and at least one radiating element in the first vertical column are part of a second radiating element array, and the second radiating element array is coupled to the second RF port via a second feed network, Wherein each of the first radiating element array and the second radiating element array is configured to operate in both a first frequency band and a second frequency band, Among them, the second radiation element array includes a first number of radiation elements when operating in the first frequency band and includes a larger number of radiation elements when operating in the second frequency band, and among them, the first radiation element array includes a second number of radiation elements when operating in the first frequency band and includes a larger number of radiation elements when operating in the second frequency band.

23. The base station antenna according to claim 22, wherein, The first radiation element array is configured to operate in some or all of the frequency bands in the 1695 - 2690 MHz frequency band but not in the 1427 - 1518 MHz frequency band, while the second radiation element array is configured to operate in some or all of the frequency bands in the 1427 - 2690 MHz frequency band including at least a part of the 1427 - 1518 MHz frequency band and at least a part of the 1695 - 2690 MHz frequency band.

24. The base station antenna according to claim 22, wherein, At least one radiation element in the second vertical column of radiation elements is coupled to the first feeding network through a first duplexer, and at least one radiation element in the first vertical column of radiation elements is coupled to the second feeding network through a second duplexer.

25. A base station antenna, comprising: A first radio frequency (RF) port; A second RF port; A first vertical column of radiation elements; And A second vertical column of radiation elements, horizontally offset relative to the radiation elements in the first vertical column; Among them, more than half of the radiation elements in the first vertical column of radiation elements are part of the first radiation element array, and the first radiation element array is coupled to the first RF port through a first feeding network, among them, more than half of the radiation elements in the second vertical column of radiation elements are part of the second radiation element array, and the second radiation element array is coupled to the second RF port through a second feeding network, among them, for RF signals in the first frequency range, the second radiation element array includes a first number of radiation elements in the first vertical column, and for RF signals in a second frequency range lower than the first frequency range, the second radiation element array includes a second number of radiation elements in the first vertical column, and the second number is greater than the first number, among them, for RF signals in a third frequency range lower than the second frequency range, the second radiation element array includes a third number of radiation elements in the first vertical column, and the third number is greater than the second number.

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