Patent Application
20140145890
The present disclosure relates to antenna assemblies including dipole elements and Vivaldi elements.
This section provides background information related to the present disclosure which is not necessarily prior art.
A common way to provide a dual polarized, dual band antenna assembly using only two radiating elements is to use separate radiating elements for the low band and the high band. For example, first and second dipole elements may be respectively used for the low and high bands.
This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.
According to various aspects, exemplary embodiments are disclosed of antenna assemblies having dipole elements and Vivaldi elements. In an exemplary embodiment, an antenna assembly generally includes a first radiating element module operable in at least a first frequency range and a second radiating element module operable in at least a second frequency range that is different than the first frequency range. The first radiating element module includes a plurality of dipole elements arranged in a dipole square. The second radiating element module includes a plurality of Vivaldi elements arranged in a crossed Vivaldi arrangement.
In another exemplary embodiment of an antenna assembly, a plurality of dipole dements define a perimeter and are operable in at least a first frequency range. First and second Vivaldi elements are within the perimeter defined by the plurality of dipole elements and operable in at least a second frequency range that is different than the first frequency range. The first and second Vivaldi elements are arranged relative to each other to form a cruciform.
In another exemplary embodiment of an antenna assembly, a plurality of dipole elements are arranged in a dipole square and operable in at least a first frequency range. First and second crossed Vivaldi elements are within a perimeter defined by the dipole square and operable in at least a second frequency range. The first and second Vivaldi elements include one or more electrically nonconductive areas configured for improved cross polarization radiation.
Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.
Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.
Example embodiments will now be described more fully with reference to the accompanying drawings.
The inventor hereof has recognized that it is difficult to develop or design an antenna element that is dual polarized, dual band, and has acceptable radiation patterns. Typically, an antenna element that provides dual band performance is usually not suitable for a dual polarized application and/or has radiation patterns that are not acceptable. After recognizing the above, the inventor hereof sought to develop antenna assemblies having separate radiating elements for the low and high bands in which the low and high band elements for each polarization are combined with a diplexing feed network.
Accordingly, the inventor has disclosed herein exemplary embodiments of dual polarized multiband antenna assemblies that include low band dipole square elements and high band crossed Vivaldi elements. In one such exemplary embodiment, an antenna assembly includes four dipole elements configured or arranged in a dipole square and operable in a first frequency range or low band (e.g., including frequencies from 698 MHz to 960 MHz, etc.). A pair of Vivaldi elements are positioned within the low band dipole square. The pair of Vivaldi elements are crossed or arranged in a cruciform and operable in a second frequency range or high band (e.g., including frequencies from 1710 MHz to 2700 MHz, etc.). The high and low band elements are combined for each polarization with a diplex feed network. Advantageously, exemplary embodiments may thus provide dual polarized dual band antenna assemblies having separate radiating element modules or assemblies (e.g., a square dipole element module and a crossed Vivaldi element module, etc.) for the low and high bands that are combined for each polarization with a diplexing feed network and that provides acceptable radiation patterns.
In exemplary embodiments, the Vivaldi elements may include cutouts on the vertical side for improved cross polarization radiation. The Vivaldi elements (with the cutout) together with the low band dipole square elements provide a more broadband antenna with good dual polarization and good radiation pattern performance.
With reference now to the figures,
The first radiating element module and its dipole elements 102, 104, 106, 108 are operable for transmitting and receiving electromagnetic radiation or signals in the first frequency range or low band (e.g., including frequencies from 698 MHz to 960 MHz, etc.) with two linear orthogonal polarizations (e.g., dual linear slant +/−45 degree or horizontal and vertical polarizations). The second radiating element module and its crossed Vivaldi elements 110, 112 are operable for transmitting and receiving electromagnetic radiation or signals in the second frequency range or high band (e.g., including frequencies from 1710 MHz to 2700 MHz, etc.) also with two linear orthogonal polarizations (e.g., dual linear slant +/−45 degree or horizontal and vertical polarizations). In an exemplary embodiment of the antenna assembly 100, the radiating elements are configured to radiate with dual linear slant +/−45 degree orthogonal polarizations. In another example embodiment of the antenna assembly 100, the radiating elements are configured to radiate with horizontal and vertical orthogonal polarizations.
The four dipole elements 102, 104, 106, 108 are positioned at right angles relative to one another. The four dipole elements 102, 104, 106, 108 are arranged in a dipole square with the dipole elements 102, 104, 106, 108 generally oriented in an orientation or aligned in an alignment of +/−45 degrees with respect to a vertical. Dipole elements 102 and 104 are also shown in
The crossed Vivaldi elements 110, 112 are arranged or positioned internally or within a perimeter or footprint defined by the dipole square formed by the dipole elements 102, 104, 106, 108. The pair of Vivaldi elements 110, 112 are crossed and oriented generally perpendicularly or orthogonally to each other, such that the Vivaldi elements 110, 112 are configured in a cruciform (
In the illustrated embodiment of
Each pair of dipole elements that are directly across from each other are fed in phase (e.g., via a diplexing feed network, etc.) and radiate with the same linear polarization. Accordingly, the dipole elements 102, 104 are fed in phase with each other and may radiate with either horizontal or vertical polarization, or they may radiate with a slant +45 degree or −45 degree linear polarization. The other dipole elements 106, 108 are also fed in phase with each other but may radiate with the other linear polarization that is orthogonal to the polarization in which the dipole elements 102, 104 radiate. For example, the dipole elements 102, 104 may radiate with horizontal polarization, while the other dipole elements 106, 108 radiate with vertical polarization. In this example, the dipole elements 102, 104 provide low band operation with horizontal polarization, while the dipole elements 106, 108 provide low band operation with vertical polarization. Conversely, the dipole elements 102, 104 may provide low band operation with vertical polarization, while the dipole elements 106, 108 may provide low band operation with horizontal polarization. In either case, the first radiating element module and its dipole elements 102, 104, 106, 108 are operable for transmitting and receiving electromagnetic radiation or signals in the first frequency range with horizontal and vertical polarizations.
By way of further example, the dipole elements 102, 104 may radiate with a +45 degree linear polarization. The other dipole elements 106, 108 may radiate with a −45 degree linear polarization, which is orthogonal to the +45 degree polarization in which the dipole elements 102, 104 radiate. In this example, the dipole elements 102, 104 provide low band operation with the +45 degree linear polarization, while the dipole elements 106, 108 provide low band operation with the −45 degree linear polarization. Conversely, the dipole elements 102, 104 may provide low band operation with the −45 degree linear polarization, while the dipole elements 106, 108 may provide low band operation with the +45 degree linear polarization. In either case, the first radiating element module and its dipole elements 102, 104, 106, 108 are operable for transmitting and receiving electromagnetic radiation or signals in the first frequency range with dual slant +/−45 degree linear orthogonal polarizations.
With reference to
As shown in
The Vivaldi elements 110, 112 may radiate with linear orthogonal polarizations relative to each other. For example, the Vivaldi element 110 may radiate with a horizontal polarization, while the other Vivaldi element 112 may radiate with a vertical polarization. Conversely, the Vivaldi element 110 may instead radiate with a vertical polarization, while the other Vivaldi element 112 may radiate with a horizontal polarization. In either case, the second radiating element module and its crossed Vivaldi elements 110, 112 are operable for transmitting and receiving electromagnetic radiation or signals in the second frequency range with horizontal and vertical polarizations.
By way of further example, the Vivaldi element 110 may radiate with a +45 degree linear polarization, while the other Vivaldi element 112 may radiate with a −45 degree linear polarization. Conversely, the Vivaldi element 110 may instead radiate with a −45 degree linear polarization, while the other Vivaldi element 112 may radiate with a +45 degree linear polarization. In either case, the second radiating element module and its crossed Vivaldi elements 110, 112 are operable for transmitting and receiving electromagnetic radiation or signals in the second frequency range with dual slant +/−45 degree linear orthogonal polarizations.
The antenna assembly 100 also includes a diplex feed network. The diplex feed network is operable for combining the low and high band elements for each polarization. For the illustrated antenna assembly 100, the diplex feed network comprises one diplex filter per port, and the diplexer is made of microstripe lines on a PCB for this example. This is but one example that may be used with the antenna assembly 100, as other types of feeds may be used in other embodiments. Alternative feed networks may also be used, such as other microstrip transmission lines, serial or corporate feeding networks, etc.
With continued reference to
The antenna assembly 100 further includes an outer reflector 130. In this example, the reflector 130 includes eight sidewalls defining a generally octagonal shape, which may help the antenna assembly 100 fit within a smaller, more aesthetic radome 152. The sidewalls extend generally perpendicular to the bottom wall of the reflector 130. In operation, the reflector 130 helps to improve the front-to-back (f/b) radiation by lowering the energy that goes back. The reflector 130 helps to reflect and direct signals from the radiating elements of the antenna assembly 100 in an outward direction. For example, the reflector 130 helps to reflect and direct signals downward when the antenna assembly 100 is mounted to a ceiling for downward looking radiation. Or, for example, the reflector 130 helps to reflect and direct signals upward when the antenna assembly 100 is placed on a surface facing upwards for upward looking radiation. Alternative embodiments may include an outer reflector that is shaped differently than octagonal, such as square, rectangular, etc. For example, another exemplary embodiment of the antenna assembly 100 may include a square reflector, which may help improve performance.
As shown in
As explained above, the dipole elements 102, 104 may radiate with a polarization orthogonal to the polarization of the other dipole elements 106, 108, e.g., horizontal and vertical polarizations or dual slant +/−45 degree linear orthogonal polarizations. Also, the Vivaldi elements 110, 112 may also radiate with linear orthogonal polarizations relative to each other, e.g., horizontal and vertical polarizations or dual slant +/−45 degree linear orthogonal polarizations. The antenna assembly 100 may thus be operable for producing linear polarized coverage for one of the two ports 132, 134 in the first and second frequency ranges and for producing linear polarized coverage for the other port 132 or 134 in the first and second frequency ranges, such that the polarizations associated with the ports 132, 134 are orthogonal to each other. Accordingly, this exemplary embodiment of an antenna assembly 100 therefore has a dual-polarized design (e.g., dual linear +/−45 degree antenna design), which may also provide, e.g., via the reflector/isolator 114 reduced coupling of the radiating antenna elements. Having radiating antenna elements with a polarization that is orthogonal to the polarization of other radiating elements may also enhance MIMO (multiple input, multiple output) performance through polarization diversity. Alternative embodiments may include more or less than two ports.
The illustrated antenna assembly 100 further includes a chassis or base 148 (broadly, a support member) and a radome or housing 152 removably mounted to the chassis 148. The radome 152 may help protect the various antenna components enclosed within the internal space defined by the radome 152 and chassis 148. The radome 152 may also provide an aesthetically pleasing appearance to the antenna assembly 100. Other embodiments may include radomes and covers configured (e.g., shaped, sized, constructed, etc.) differently than disclosed herein within the scope of the present disclosure.
The radome 152 may be attached to the chassis 148 by mechanical fasteners (e.g., screws 156 and O-rings 158 (
A wide range of suitable materials may be used for the various components of the antenna assembly 100. By way of example only, an exemplary embodiment includes aluminum dipole elements 102, 104, 106, 108 and aluminum reflectors 114 and 130. The substrates 126 of the Vivaldi elements 110, 112 may be FR4, which is a composite material of woven fiberglass cloth with an epoxy resin binder that is flame resistant. The Vivaldi radiating elements 124 may be copper (e.g., copper traces on a printed circuit board, copper metallization, etc.). A wide range of materials, configurations (e.g., sizes, shapes, constructions, etc.), and manufacturing processes may also be used for the chassis 148 (which may also or instead be referred to as a ground plane) and radome 152. In various exemplary embodiments, the radome 152 is injection molded plastic or vacuum formed out of thermoplastic, and the chassis or ground plane 148 is electrically conductive (e.g., aluminum, etc.) for electrically grounding the radiating antenna elements. Alternative embodiments may include other one or more components formed from other electrically-conductive materials (e.g., other metals besides aluminum and copper, etc.) and/or other dielectric materials for the Vivaldi substrate besides FR4. In addition, other exemplary embodiments may be configured to be operable in more than two bands and/or different frequency bands.
In addition to the components mentioned above,
As shown in
A description will now be provided of an exemplary method by which the exemplary embodiment of the antenna assembly 100 may be assembled together. This method and the various steps thereof are provided for purpose of illustration only as other embodiments may include a different process to assemble an antenna assembly, including a different order of the steps, one or more different steps, one or more additional steps, etc.
With reference to
The feed probes 103, 105 (
The dipole elements 102, 104, 106, 108 are mounted to the reflector 130 using mechanical fasteners 161 (e.g., using 12 MRT-TTscrews, etc.), which may be tightened (e.g., 75 Newton-centimeter (N-cm), etc.) with an appropriate torque wrench tooling. At this stage, the top threaded portions of the standoffs 163 extend through holes 170 (
The reflector 114 may next be assembled by first applying adhesive 167 to the outside of the small flanges on the reflector walls 116, 118 as shown in
Two cable connector grounds 169 are mounted from underneath the PCB 113 and solder all around. Adhesive 162 is mounted and attached to the PCB 113, and used to mount the PCB 113 to the reflector 130. A guiding fixture may be used as necessary during this operation of mounting the PCB 113 to the reflector 130.
The PCBs of the Vivaldi elements 110, 112 are positioned relative to the reflector 130 such that the Vivaldi grounding portions or tabs 117 are positioned through openings (e.g., holes, slots, etc.) in the reflector 130. Then, the grounding portions 117 are electrically connected (e.g., soldered, etc.) to corresponding grounding portions of the PCB 113, to thereby ground the Vivaldi elements 110, 112 to the PCB 113. In addition, the probes 119 of the Vivaldi elements 110, 112 are positioned through openings (e.g., holes, slots, etc.) in the reflector 130 and also through openings (e.g., holes, slots, etc.) in the PCB 113. Then, the probes 119 are electrically connected (e.g., soldered, etc.) to a feed network. By way of example, the Vivaldi PCBs may be pushed (e.g., via the non-copper side, etc.) against the reflector 130 in order to ensure correct positioning. By way of further example, this exemplary embodiment includes a total of eight grounding tabs 117.
Coaxial cables 133, 135 are soldered to the connectors 132, 134, for example, by using a resistance soldering tool after removing the O-rings from the connectors to prevent melting during the soldering process. The coaxial cables 133, 135 are preferably formed in a specially designed fixture in order to match the shape of the cavities in the base 148. The braids of the coaxial cables 133, 135 are soldered to the cable connector grounds 169. The center conductors of the coaxial cables 133, 135 are soldered to the PCB 113. The removed O-rings are inserted or added back onto the connectors 132, 134. The connectors 132, 134 are pulled through holes of the base 148. Screws 160 may then be tightened (e.g., with torque of 50 N-cm, etc.) to thereby attach the reflector 130 to the base 148. A washer and nut may be assembled onto the connectors 132, 134 and tightened (e.g., to 150 N-cm with torque wrench tool, etc.). The connectors 132, 134 face downward when the antenna assembly 100 is in the upright position.
Sealant (e.g., 3M sealant 5200 FC, etc.) is applied circumferentially to an inner surface of the radome 152 along the entire perimeter of the radome 152, e.g., five millimeters from the bottom of the radome 152, etc. Sealant may also be applied along an perimeter edge of the base 148. The radome 152 is mounted to the base 148 using screws 156 and O-rings 158, which screws 156 may be tightened with torque of 75 N-cm, etc. The sealant is allowed to cure horizontally with the connectors facing downward. One or more labels may be applied to the bottom of the base 148.
More specifically,
Generally,
Azimuth plane radiation patterns were also measured for the first and second ports of the same prototype of the antenna assembly 100 at various frequencies. The results are summarized in the table below for the first and second ports respectively referred to as Port1 and Port2 in the table.
The radiation pattern test results show that the antenna assembly 100 has a bandwidth spread of 56° to 71° for the low band from 698 MHz to 960 MHz and 48° to 81° for the high band from 1710 MHz to 2700 MHz. The gain (+/−0.5 decibels (dB)) was 8.2 dB to 9.7 dB for the low band and 5.7 dB to 9.5 dB for the high band. The front to back ratio was greater than 16.9 dB for the low band, and only the frequency 1880 MHz had a front to back ratio less than 15 dB for the high band. Generally, this testing shows that the antenna assembly 100 has good bandwidth spread, good gain, and good directivity with a high front to back ratio for the low band from 698 MHz to 960 MHz and the high band from 1710 MHz to 2700 MHz.
As noted above, these analysis results are provided only for purposes of illustration and not for purposes of limitation. An FAI sample or prototype of the antenna assembly 100 or other antenna assembly disclosed herein may have other values for the VSWR for port1 and port2 and/or other values for the isolation between port1 and port2.
By way of further example only, a second prototype or FAI sample of the antenna assembly 100 was created and tested. The second sample also had a good VSWR of less than 2, good isolation, good bandwidth spread, good gain, and good directivity with a high front to back ratio for frequencies within a low band from 698 MHz to 960 MHz and for frequencies within a high band from 1710 MHz to 2700 MHz. More specifically, the VSWR for port1 was 1.1487 at 698 MHz, 1.6547 at 960 MHz, 1.3517 at 1710 MHz, and 1.6924 at 2700 MHz. The VSWR for port2 was 1.1846 at 698 MHz, 1.5385 at 960 MHz, 1.6558 at 1710 MHz, and 1.3966 at 2700 MHz. The isolation between port1 and port2 was −36.612 dB at 698 MHz, −39,832 dB at 960 MHz, −28.034 dB at 1710 MHz, and −28.615 dB at 2700 MHz. The bandwidth spread was 57° to 71° for the low band and 48° to 78° for the high band. The gain (+/−0.5 decibels (dB)) was 8.2 dB to 9.7 dB for the low band from 698 MHz to 960 MHz and 6.1 dB to 9.8 dB for the high band from 1710 MHz to 2700 MHz. The front to back ratio was greater than 16.9 dB for the low band, and only the frequency 1880 MHz had a front to back ratio less than 15 dB for the high band.
In exemplary embodiments, an antenna assembly may be housed in a relatively low profile ceiling-mountable or tabletop appropriate package. By way of example, an antenna assembly disclosed herein may include ceiling/wall mounting clips and/or other means (e.g., mechanical fasteners, adhesives, frame-style mounts, etc.) for mounting and suspending the antenna assembly from a ceiling or other suitable structure. By way of further example, an antenna assembly disclosed herein may be used in systems and/or networks such as those associated with wireless internet service provider (WISP) networks, broadband wireless access (BWA) systems, wireless local area networks (WLANs), cellular systems, etc. The antenna assemblies may receive and/or transmit signals from and/or to the systems and/or networks within the scope of the present disclosure.
Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms, and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. In addition, advantages and improvements that may be achieved with one or more exemplary embodiments of the present disclosure are provided for purpose of illustration only and do not limit the scope of the present disclosure, as exemplary embodiments disclosed herein may provide all or none of the above mentioned advantages and improvements and still fall within the scope of the present disclosure.
Specific dimensions, specific materials, and/or specific shapes disclosed herein are example in nature and do not limit the scope of the present disclosure. The disclosure herein of particular values and particular ranges of values (e.g., frequency ranges, etc.) for given parameters are not exclusive of other values and ranges of values that may be useful in one or more of the examples disclosed herein. Moreover, it is envisioned that any two particular values for a specific parameter stated herein may define the endpoints of a range of values that may be suitable for the given parameter (i.e., the disclosure of a first value and a second value for a given parameter can be interpreted as disclosing that any value between the first and second values could also be employed for the given parameter). Similarly, it is envisioned that disclosure of two or more ranges of values for a parameter (whether such ranges are nested, overlapping or distinct) subsume all possible combination of ranges for the value that might be claimed using endpoints of the disclosed ranges.
The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a”, “an” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.
When an element or layer is referred to as being “on”, “engaged to”, “connected to” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to”, “directly connected to” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
The term “about” when applied to values indicates that the calculation or the measurement allows some slight imprecision in the value (with some approach to exactness in the value; approximately or reasonably close to the value; nearly). If, for some reason, the imprecision provided by “about” is not otherwise understood in the art with this ordinary meaning, then “about” as used herein indicates at least variations that may arise from ordinary methods of measuring or using such parameters. For example, the terms “generally”, “about”, and “substantially” may be used herein to mean within manufacturing tolerances. Whether or not modified by the term “about”, the claims include equivalents to the quantities.
Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.
Spatially relative terms, such as “inner,” “outer,” “beneath”, “below”, “lower”, “above”, “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements, intended or stated uses, or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.
