Patent Application
20230291103
This application is a continuation of U.S. Application Serial No. 17/181,443, filed Feb. 22, 2021, now U.S. Pat. No., which claims priority to Chinese Patent Application No. 202010212479.0, filed Mar. 24, 2020, the disclosures of which are hereby incorporated herein by reference.
The present invention relates to communication systems and, more particularly, to multi-band antennas and radiating element assemblies that are suitable for communication systems.
A director is a device that is mounted adjacent a radiating element in order to: (i) tune a radiation pattern of the radiating element, such as a lobe width of the radiation pattern, and/or (ii) improve a return loss (RL) of the radiating element. A dimension and shape of the director will affect its working frequency band. Therefore, the dimension and shape of the director may need to be adjusted according to an operating frequency of the radiating element that the director serves. A distance between the director and the radiating element that the director serves will also affect the tuning of the radiation pattern. Accordingly, the distance between the director and the radiating element may also need to be adjusted to achieve a desired radiation pattern.
An enhanced multi-band antenna according to some embodiments of the invention includes a first radiating element configured to emit first electromagnetic radiation in response to at least one feed signal having a frequency within a first radio frequency (RF) band. A director is also provided, which is positioned forwardly of the first radiating element, and directly in a path of the first electromagnetic radiation. The director includes first and second passive impedance elements, which provide respective first and second frequency-dependent reactances to first currents, which are induced within the director in response to the first electromagnetic radiation.
In some of these embodiments, the first and second passive impedance elements include a first inductor and a first capacitor, which are electrically coupled in series. For example, the director may be configured to include a plurality of passive impedance elements that are connected within a closed impedance loop, which contains a second LC circuit in series with a first LC circuit. As another example, the director may be configured to include a plurality of passive impedance elements that are connected within a closed resonant loop containing a third LC circuit in series with a second LC circuit, which is in series with a first LC circuit.
In some other embodiments of the invention, the director is positioned adjacent a path of second electromagnetic radiation emitted by a second radiating element, and the director is configured to provide a greater frequency-dependent impedance to second currents induced within the director in response to the second electromagnetic radiation relative to the first currents. In addition, a distance between the director and a forward-facing surface of the first radiating element may be in a range from λ/8 to 3λ/8 (e.g., λ/4), where λ is equivalent to a wavelength of a center frequency within the first RF band (and the director extends parallel to radiating arms within the first radiating element).
According to further embodiments of the invention, a geometric shape of the capacitor in the first LC circuit is equivalent to a geometric shape of the capacitor in the second LC circuit, and a geometric shape of the inductor in the first LC circuit is equivalent to a geometric shape of the inductor in the second LC circuit. The geometric shape of the capacitor in the first LC circuit may be selected from a group consisting of four-sided polygons (e.g., rectangles, diamond-shape), triangles, circles, and circular sectors.
In still further embodiments of the invention, a multi-band antenna includes: (i) a reflector, (ii) a first array of first radiating elements, which extend in a lengthwise direction along a first side of the reflector, and (iii) a second array of first radiating elements, which extend in a lengthwise direction along a second side of the reflector. An array of second radiating elements is also provided, which extends in a lengthwise direction across the reflector, and between the first and second arrays of first radiating elements. An array of directors is provided, which extends forwardly of the first radiating elements within the first array. The directors are configured to include respective closed resonant loops of inductor and capacitor elements connected in series. Advantageously, each of the resonant loops provides a frequency-dependent impedance that is greater with respect to second currents, which are induced within the resonant loops in response to radiation from the second radiating elements, relative to first currents, which are induced within the resonant loops in response to radiation from the first radiating elements. In some embodiments, each of the resonant loops includes an alternating arrangement of inductors and capacitors. And, a geometric shape of the capacitors may be selected from a group consisting of four-sided polygons (e.g., rectangles), triangles, circles, and circular sectors. In some embodiments, all of the capacitors within a respective loop have equivalent shapes and area; but, in other embodiments, some of the capacitors within a respective loop have different shapes and area.
According to still further embodiments of the invention, a multi-band antenna is provided, which includes a first radiating element configured to emit first electromagnetic radiation in response to at least one feed signal having a frequency within a first radio frequency (RF) band. A director is provided, which is positioned forwardly of the first radiating element, and in a path of the first electromagnetic radiation. The director includes a two-dimensional grid-shaped inductor. In some of these embodiments, the two-dimensional grid-shaped inductor has a two-dimensional array of openings therein. And, a side dimension of the openings may be equal to λ/10, where λ is equivalent to a wavelength of a center frequency within the first electromagnetic radiation. The two-dimensional array of openings may be larger than a two-by-two array of openings.
The accompanying drawings, which constitute a part of the specification, illustrate embodiments of the present invention and, together with the description, serve to explain the principles of the present invention.
Note, that in some cases the same elements or elements having similar functions are denoted by the same reference numerals in different drawings, and description of such elements is not repeated. In some cases, similar reference numerals and letters are used to refer to similar elements, and thus once an element is defined in one figure, it need not be further discussed in subsequent figures.
In order to facilitate understanding, the position, dimension, range, or the like of each structure illustrated in the drawings may not be drawn to scale. Thus, the invention is not necessarily limited to the position, dimension, range, or the like as disclosed in the drawings.
The present invention will be described with reference to the accompanying drawings, which show a number of example embodiments thereof. It should be understood, however, that the present invention can be embodied in many different ways, and is not limited to the embodiments described below. Rather, the embodiments described below are intended to make the disclosure of the present invention more complete and fully convey the scope of the present invention to those skilled in the art. It should also be understood that the embodiments disclosed herein can be combined in any way to provide many additional embodiments.
The terminology used herein is for the purpose of describing particular embodiments, but is not intended to limit the scope of the present invention. All terms (including technical terms and scientific terms) used herein have meanings commonly understood by those skilled in the art unless otherwise defined. For the sake of brevity and/or clarity, well-known functions or structures may be not described in detail.
Herein, when an element is described as located “on” “attached” to, “connected” to, “coupled” to or “in contact with” another element, etc., the element can be directly located on, attached to, connected to, coupled to or in contact with the other element, or there may be one or more intervening elements present. In contrast, when an element is described as “directly” located “on”, “directly attached” to, “directly connected” to, “directly coupled” to or “in direct contact with” another element, there are no intervening elements present. In the description, references that a first element is arranged “adjacent” a second element can mean that the first element has a part that overlaps the second element or a part that is located above or below the second element.
Herein, the foregoing description may refer to elements or nodes or features being “connected” or “coupled” together. As used herein, unless expressly stated otherwise, “connected” means that one element/node/feature is electrically, mechanically, logically or otherwise directly joined to (or directly communicates with) another element/node/feature. Likewise, unless expressly stated otherwise, “coupled” means that one element/node/feature may be mechanically, electrically, logically or otherwise joined to another element/node/feature in either a direct or indirect manner to permit interaction even though the two features may not be directly connected. That is, “coupled” is intended to encompass both direct and indirect joining of elements or other features, including connection with one or more intervening elements.
Herein, terms such as “upper”, “lower”, “left”, “right”, “front”, “rear”, “high”, “low” may be used to describe the spatial relationship between different elements as they are shown in the drawings. It should be understood that in addition to orientations shown in the drawings, the above terms may also encompass different orientations of the device during use or operation. For example, when the device in the drawings is inverted, a first feature that was described as being “below” a second feature can be then described as being “above” the second feature. The device may be oriented otherwise (rotated 90 degrees or at other orientation), and the relative spatial relationship between the features will be correspondingly interpreted.
Herein, the term “A or B” used through the specification refers to “A and B” and “A or B” rather than meaning that A and B are exclusive, unless otherwise specified
The term “exemplary”, as used herein, means “serving as an example, instance, or illustration”, rather than as a “model” that would be exactly duplicated. Any implementation described herein as exemplary is not necessarily to be construed as preferred or advantageous over other implementations. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the detailed description.
Herein, the term “substantially”, is intended to encompass any slight variations due to design or manufacturing imperfections, device or component tolerances, environmental effects and/or other factors. The term “substantially” also allows for variation from a perfect or ideal case due to parasitic effects, noise, and other practical considerations that may be present in an actual implementation.
Herein, certain terminology, such as the terms “first”, “second” and the like, may also be used in the following description for the purpose of reference only, and thus are not intended to be limiting. For example, the terms “first”, “second” and other such numerical terms referring to structures or elements do not imply a sequence or order unless clearly indicated by the context.
Further, it should be noted that the terms “comprise”, “include”, “have” and any other variants, as used herein, specify the presence of stated features, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof.
In a multi-band antenna, a director that is mounted, for example, forwardly of a first radiating element that has a first operating frequency band may affect a radiation pattern of a second radiating element having a second operating frequency band. A multi-band antenna according to an embodiment of the present invention includes a first radiating element configured to emit electromagnetic radiation within a first operating frequency band, a second radiating element configured to emit electromagnetic radiation within a second operating frequency band, and a director configured to shape the radiation pattern of the first radiating element. The director is frequency selective so as to be substantially invisible to electromagnetic radiation within at least a portion of the second operating frequency band. Consequently, a director that is associated with the first radiating element may have a reduced impact on the radiation pattern of the second radiating element. Embodiments of the present invention further provide radiating element assemblies including frequency selective directors, and frequency selective directors. Directors herein are also referred to as “parasitic elements” or “parasitic element assemblies” in some embodiments.
The multi-band antenna 100 further includes an array of radiating elements 110, an array of radiating elements 120, and an array of radiating elements 130 that are arranged on a front side of the reflector 160. In the illustrated embodiment, an operating frequency band of the radiating elements 110 may be, for example, 1695 to 2690 MHz (hereinafter abbreviated as VB) or a sub-band thereof (e.g., 1695 to 2200 MHz, 2300 to 2690 MHz, or the like). An operating frequency band of the radiating element 120 may be, for example, 3.1 to 4.2 GHz (hereinafter abbreviated as SB) or a sub-band thereof. An operating frequency band of the radiating element 130 may be, for example, 694 to 960 MHz (hereinafter abbreviated as RB) or a sub-band thereof. The array of VB radiating elements 110 includes two vertically-extending linear arrays that are adjacent in a horizontal direction. According to how these radiating elements 110 are fed, the two linear arrays may be configured to form two separate antenna beams, or may be configured to form a single antenna beam. The array of SB radiating elements 120 extends vertically and is disposed between these two linear arrays. The array of RB radiating elements 130 extends vertically and is disposed between the two linear arrays. The radiating elements 130 are staggered horizontally a slight offset to either side of the longitudinal axis of the antenna 100, so as to obtain a narrower antenna beam in the azimuth plane.
The multi-band antenna 100 further includes parasitic elements 150, 170 extending forwardly from the reflector 160. The parasitic elements 150 are disposed near both edges of the reflector 160 outside of each linear array of radiating elements 110 so as to tune the pattern of the antenna beam generated by the two linear arrays of radiating elements 110. The parasitic elements 170 are disposed on both sides of the array of radiating elements 120, and between the array of the radiating elements 120 and each linear array of radiating elements 110 so as to improve the isolation between the radiating elements 120 and the radiating elements 110 and to tune the pattern of the antenna beam generated by the array of radiating elements 120.
The multi-band antenna 100 further includes a plurality of directors 140 for the VB radiating elements 110, respectively. In the illustrated embodiment, radiating arms of the radiating element 110 define a first plane, and the director 140 extends substantially parallel to the first plane. The center of each director 140 may be positioned on or near a maximum radiation direction of the corresponding radiating element 110. For example, a projection of the director 140 on the first plane is basically located in a center section of a projection of the radiating element 110 on the first plane, so as to tune the radiation pattern and the return loss of the radiating element 110. A distance from the director 140 to the first plane, which affects the tuning, may be adjusted as needed. In an embodiment, the distance from the director 140 to the first plane is configured to be around ¼ of a wavelength corresponding to a center frequency of the electromagnetic radiation that is emitted by the radiating element 110. In another embodiment, the distance from the director 140 to the first plane is configured to be ⅛ to ⅜ of the wavelength corresponding to the center frequency of the electromagnetic radiation that is emitted by the radiating element 110. Unless otherwise specified herein, a “wavelength” herein refers to the wavelength of an electromagnetic wave in a vacuum or air.
A dimension of the projection of the director 140 on the first plane (for example, the diagonal dimension) may be around ¼ of the wavelength corresponding to the center frequency of the electromagnetic radiation that is emitted by the radiating element 110. If the director 140 that is associated with one of the radiating elements 110 in antenna 100 is replaced with a conventional director 520 that is illustrated in
Each director 140 is configured to be frequency selective such that they will be substantially invisible to at least a portion of the electromagnetic radiation (e.g., having a given frequency) emitted by the SB radiating element 120. Therefore, the impact of the directors 140 on the electromagnetic radiation emitted by the radiating elements 120 is reduced. As shown in
Surface currents in a director are mainly distributed at the edges of the director. Therefore, different shapes of directors lead to different distributions of surface currents, so as to lead to resonant circuits with different amplitude-frequency curves. In addition, in the LC series resonant circuit, the greater the number of LC circuits (for example, the number of LC circuits in the director 140 is 4), the steeper the amplitude-frequency curve of the resonant circuit and the narrower the passband of the resonant circuit. The shape of the director may be designed as needed so that the resonance strength of the resonant circuit formed in the director is sufficient to tune the radiation pattern of its associated radiating element, and at least a portion of the operating frequency band of the another radiating element is outside of the passband of the resonant circuit.
A process for designing a “cloaking” director for a first radiating element that has a first operating frequency band and is substantially invisible to a second radiating element having a second operating frequency band may include: determining a resonance frequency and a passband width of the resonant circuit that is formed in the director, determining the capacitance and inductance of the resonant circuit according to the resonance frequency and then determining the area(s) of the capacitive element(s) and the length(s) of the inductive element(s), and determining the number of LC circuits according to the passband width, such that the resonant circuit formed by connecting the capacitive element(s) and inductive element(s) may be substantially invisible to electromagnetic radiation within the second operating frequency band. The design process may then include adjusting the shape and dimension of each capacitive element and inductive element, the distance between two adjacent capacitive elements, the distance between a capacitive element and an adjacent inductive element, and the distance between the director and the first radiating element, such that the director including the resonant circuit may tune the radiation pattern and return loss of the first radiating element.
In some embodiments, an LC series resonant circuit formed in a director may not be a loop.
In some embodiments, a director that is associated with a first radiating element having a first operating frequency band that is substantially invisible to a second radiating element having a second operating frequency band includes one or more inductive elements formed therein. The inductance of each of the one or more inductive elements may be configured, such that the director has a higher impedance within the second operating frequency band and has a lower impedance within the first operating frequency band, so as to reduce a current within the second operating frequency band and substantially not reduce a current within the first operating frequency band.
The dimension d of each hole 620 may be much smaller than a wavelength corresponding to a center frequency of the first operating frequency band of the radiating element associated with the director 600. The wavelength here may be the wavelength of electromagnetic waves in a vacuum or air, or the wavelength of electromagnetic waves in the director 600. In an embodiment, the dimension d of the hole 620 is smaller than ⅒ of the wavelength corresponding to the center frequency of the first operating frequency band. The width w of each of the inductive sections 611 through 614 may be much smaller than the dimension d of the hole 620. In an embodiment, the width w of each of the inductive sections 611 through 614 is smaller than ⅒ of the dimension d of the hole 620. The dimension d of the hole 620 herein may refer to the dimension of the hole 620 in any direction (e.g., a horizontal direction, a vertical direction, a diagonal direction, or another oblique direction from the perspective shown in
In the illustrated embodiment, the shape of the hole 620 is substantially square. It will be appreciated that, in other embodiments, the shape of the hole 620 may be a triangle, a rectangle, other polygons, a circle, an oval, or an irregular shape. In the illustrated embodiment, the hole array is a substantially square array formed of a plurality of holes 620. It will be appreciated that, in other embodiments, the hole array may be a rectangular array, a diamond array, a triangular array, a circular array, a cross array, or an irregularly-shaped array formed of a plurality of holes 620. In the illustrated embodiment, the director 600 is configured generally as a rectangle. It will be appreciated that, in other embodiments, the director 600 may be configured substantially as a quadrangle, a triangle, a circle, a sector, a cross, a T-shape, an L-shape, or an irregular shape.
Each of the directors (also referred to as a parasitic element or a parasitic element assembly) in any of the foregoing embodiments of the present invention may be formed of a metal plate or a printed circuit board with conductor(s) being printed on a dielectric board.
The radiating element assembly according to embodiments of the present invention, as shown in
The director 420 in the radiating element assembly may be oriented at an arbitrary angle with respect to the radiating element 410. In the case that the radiating element is a crossed dipole radiating element 410, a diagonal of the director 420 is at an angle within a range of 0 to 45 degrees relative to a diagonal of the radiating element 410. A diagonal of the radiating element 410 may be a line connecting the tail end of one radiating arm in a dipole to the tail end of the other radiating arm in the dipole of the radiating element 410. In the embodiment shown in
Accordingly, as described hereinabove, an enhanced multi-band antenna 100 includes a first radiating element 110, which is configured to emit first electromagnetic radiation in response to at least one feed signal having a frequency within a first radio frequency (RF) band. A director 140 is also provided, which is positioned forwardly of the first radiating element 110, and directly in a path of the first electromagnetic radiation. The director 140 includes first and second passive impedance elements (e.g., L and C), which provide respective first and second frequency-dependent reactances to first currents, which are induced within the director 140 in response to the first electromagnetic radiation. As will be understood by those skilled in the art, an impedance ZL of an inductor L can be specified as ZL = RL + j wL, and an impedance Zc of a capacitor C can be specified as Zc = Rc + 1/j wC, where RL and Rc are the built-in resistances of the inductor and capacitor, wL and 1/wC are the reactances of the inductor and capacitor, and w is the angular frequency of the electromagnetic radiation.
As shown by
As further shown by
As shown by
Although some specific embodiments of the present invention have been described in detail with examples, it should be understood by a person skilled in the art that the above examples are only intended to be illustrative but not to limit the scope of the present invention. The embodiments disclosed herein can be combined arbitrarily with each other, without departing from the scope and spirit of the present invention. It should be understood by a person skilled in the art that the above embodiments can be modified without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the attached claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202010212479.0 | Mar 2020 | CN | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 17181443 | Feb 2021 | US |
| Child | 18185332 | US |
