Patent Application
20180083368
The present invention relates to a directive antenna and, more particularly, to a vertically polarized, physically compact panel antenna for use in wireless data communication.
Conventional panel antennas are available in a number of different configurations and materials. However, existing configurations of the conventional panel antenna tend to have excessive side lobe radiation, which may cause electromagnetic interference, and which is wasteful from an energy efficiency standpoint. For example, in receiving antennas, side lobes may pick up interfering signals and increase the noise level in the receiver. Further, many conventional panel antennas do not possess satisfactory directional gain (i.e., have a poor front to back ratio) and often suffer from strong wind load due to their physical configuration. This makes certain conventional antennas unsuitable for use in high-wind environments, such as areas prone to hurricanes and tornados. Additionally, the materials used in the fabrication of conventional panel antenna tend to result in higher than optimal manufacturing costs. A panel antenna having a high directional gain performance, high efficiency, low cost and good ability to withstand a strong wind load is preferred.
The invention relates generally to a vertically polarized and physically compact low band panel antenna that has a high directional gain performance and good ability to withstand a strong wind. Embodiments of the present invention provide a panel antenna assembly including a double bend reflector, an N×M array of dipole elements, a five-sided cover, and at least one rigid and integrated feed line.
Further, in certain embodiments, the double bend reflector comprises a plurality of side walls, which defines therebetween an interior portion of the reflector. The double bend reflector is further formed by bending each of the plurality of side walls in a first direction along a first crease at an edge of the interior portion followed by bending each of the plurality of side walls in an opposite second direction along a second crease offset from the first crease. Further, the N×M array of dipole elements is symmetrically disposed within said interior portion and is in electrical contact with the feed line. Moreover, the five-sided cover contains a substantially square top portion and four cover sides, which are attached to and extended downwardly and outwardly from the top portion. In addition, the top portion comprises a dome.
In certain embodiments, the assembly further comprises a mounting assembly, which includes a first bracket, a second bracket and a concave brace. In other embodiments, the mounting assembly further contains a first pole-mounting bracket, a second pole-mounting bracket, a third pole-mounting bracket, and a fourth pole-mounting bracket.
In certain embodiments of the dipole elements each of the dipole element formed with a single metal sheet comprising a top portion which is electrically connected to a bottom support structure incorporating a j hook electrical antenna element. Further, in certain embodiments, a distance between a top center portion of each of the dipole elements and the closest interior portion of the reflector has a range from 50 mm to 85 mm. In other embodiments, the distance between the top center portion of each of the dipole elements and the closest interior portion of the reflector is about 78 mm. In yet other embodiments, this distance is a minimum of 90 mm, and nominally 100 mm. Additionally, in certain embodiments, each of the dipole elements is disposed at a distance of about 220 mm in parallel to an adjacent dipole element and at a distance of about 240 mm in diagonal to an adjacent dipole element.
Embodiments of the invention have certain advantages. By providing a u-shaped, rigid support structure under the antenna radome, antennas according to certain embodiments can withstand increased wind loads compared to conventional designs. Additionally, by providing a steel, symmetrical support structure under the antenna reflector, which is mechanically coupled to a mounting bracket, and then to a mast, antennas according to embodiments of the invention can be more securely mounted during installation as compared with conventional designs incorporating aluminum mounting hardware. Embodiments of the invention use printed circuit board (“PCB”) connections from the antenna feed line to each individual dipole antenna element. This eliminates the need for cables and cable connectors, which provides reduced PIM and interference, particularly when the antenna is subject to mechanical shock. The use of an array of dipole radiators, arranged at a diagonal with respect the reflector walls, provides for less side lobe gain, a higher F/B ratio, and more forward gain, i.e., better directionality and lower interference. In particular, embodiments of the invention provide a minimal spacing between edge dipole elements and the interior walls of the reflector, which reduces fringing effects and leaking of energy into side lobes. Additional advantages will be evident to the person of ordinary skill in the art in view of the following detailed description.
The invention will be more fully understood by referring to the following Detailed Description of Specific Embodiments in conjunction with the Drawings, of which:
References throughout this specification to “one embodiment,” “an embodiment,” “a related embodiment,” or similar language mean that a particular feature, structure, or characteristic described in connection with the referred to “embodiment” is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment,” “in an embodiment,” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment. It is to be understood that no portion of disclosure, taken on its own and in possible connection with a figure, is intended to provide a complete description of all features of the invention.
In addition, the following disclosure may describe features of the invention with reference to corresponding drawings, in which like numbers represent the same or similar elements wherever possible. In the drawings, the depicted structural elements are generally not to scale, and certain components are enlarged relative to the other components for purposes of emphasis and understanding. It is to be understood that no single drawing is intended to support a complete description of all features of the invention. In other words, a given drawing is generally descriptive of only some, and generally not all, features of the invention. A given drawing and an associated portion of the disclosure containing a description referencing such drawing do not, generally, contain all elements of a particular view or all features that can be presented is this view, for purposes of simplifying the given drawing and discussion, and to direct the discussion to particular elements that are featured in this drawing. A skilled artisan will recognize that the invention may possibly be practiced without one or more of the specific features, elements, components, structures, details, or characteristics, or with the use of other methods, components, materials, and so forth. Therefore, although a particular detail of an embodiment of the invention may not be necessarily shown in each and every drawing describing such embodiment, the presence of this detail in the drawing may be implied unless the context of the description requires otherwise. In other instances, well known structures, details, materials, or operations may be not shown in a given drawing or described in detail to avoid obscuring aspects of an embodiment of the invention that are being discussed.
The invention as recited in claims appended to this disclosure is intended to be assessed in light of the disclosure as a whole.
Embodiments of Applicant's invention are disclosed to describe a vertically polarized low band panel antenna. Antennas according to the invention have a high performance and efficiency, and are particularly well suited for roof-top mounting locations where the antenna may serve as a link between cellular Base Station (BTS) and an in-building repeater or distributed antenna system (DAS) to improve in-building cellular data coverage. At a high level, embodiments of the invention include an array of center tap dipole radiators located within a rectangular reflector, where the radiators are fed with an integrated feed line (i.e., PCB feed line), as opposed to with cables, in certain embodiments, as few as 9 radiators are used, and no radiator is within about 25 mm of a wall of the reflector, and preferably, is greater than 90 mm from a wall of the reflector. As described herein, “about” is used to show a plus or minus difference of 10% in any measurement. The radiators are covered by a polymeric radome, resulting in an overall package that is compact and able to withstand a high wind load.
Referring to
In certain embodiments, the double bend reflector 200 is formed from a metal plate by bending all side walls 202, 204, 206, 208 first downwardly along a first crease 220 (
Moreover, in accordance with preferred embodiments of the present invention, the metal used to form the double bend reflector 200 is aluminum. However, it is known to a person of ordinary skill in radio antenna and wireless communication fields, other suitable types of metals can be used to form the double bend reflector. The aluminum metal plate has a thickness of about 2 mm to about 3.5 mm, with a preferred embodiment of 3 mm.
Referring now to
When the five-side cover 300 is disposed within the interior portion 218 of the reflector 200 to form the panel antenna 100 (
In certain embodiments, the top portion 318 comprises a dome 320, which is disposed substantially in the middle of the top portion 318. The dome 320 is located at a distance of about 150 mm to 200 mm away from each of four edges of the top portion 318, with a preferred distance of about 170 mm. The dome 320 comprises a radius of curvature 332 about an axis 330 and a transverse curvature 334 about the axis 330, which is parallel to the vertical y-axis 320. The dome 320 with the radius of curvatures 332 and 334 helps to improve the panel antenna 100's ability to withstand a high wind load with a survival wind speed of about 273 km/h when mounted to a structure outdoor, which is substantially higher than a panel antenna with a flat cover. In certain embodiments, each of the side walls of the reflector 200 (
Additionally, in accordance with preferred embodiments of the present invention, the materials used to manufacture the five-sided cover 300 can be hand laid fiber glass. In other embodiments, the materials used to manufacture the five-sided cover can be thermo formed plastics. However, as is known to a person of ordinary skill in radio antenna and wireless communication fields, other types of electrically insulative materials are suitable to protect an array of dipole elements and are able to withstand a certain wind load can be used to form the five-sided cover 300.
Referring to
Further,
Further, in a preferred embodiment, each of the dipole elements is coupled to a feed line in a way such that each dipole element is parallel to a diagonal line 402 of the interior portion 218 and is at a right angel to a diagonal line 404 of the interior portion 218. In a preferred embodiment, the distance in parallel between a dipole element 500 and a dipole element 502 is about 220 mm. Moreover, the distance in diagonal between the dipole element 500 and a dipole element 504 is about 240 mm. Similarly, with specific values chosen for this embodiment are recited, it is to be understood that, within the scope of the invention, the values of distances in parallel and/or in diagonal can vary over wide ranges to suit different applications.
In certain embodiments, the dipole element 500 comprises a top portion 506 and a bottom portion 508, which includes stem portion 524, which act as a support post. Bottom portion 508 also incorporates a j hook shaped conductor, electrically coupled to the feed line, which disposed in the stem portion 524 of the bottom portion 508. The j hook conductor is more clearly visible in
In addition, in some embodiments, the bottom portion 508 comprises a stern 524 connecting to the ledge 514, which is orthogonal to the middle portion 510 and a foot 526, which comprises an aperture 528 extending therethrough for attaching to the divider or the PCB of the divider. In some embodiments, a wide foot 526 is used because the wider the foot, the better support for a dipole element is provided, especially under vibration. Further, the stem 524 has a height 530 of about 50 mm to about 85 mm, with a preferred embodiment of about 78 mm.
The other feature besides the features of the dome 320 of the five-sided cover 300 and the plurality of apertures in the side walls of the reflector 200 contributing to increased survival wind speed is Applicant's mounting assembly 600 as illustrated in
In certain embodiments, the first bracket 610 comprises a substantially rectangular middle plate 612 with a first width 614, a second width 616, a first length 618, a second length 620, a first bracket side 622, and a second bracket side 624. Further, the first bracket side 622 is substantially orthogonal to the middle plate 612 and flanks the middle plate 612 along the length 618; and the second bracket side 624 is substantially orthogonal to the middle plate 612 and flanks the middle plate 612 along the length 620. The second bracket 620 has a similar structure as the first bracket 610 with one difference that a width 626 of a middle plate 628 is larger than the width of the middle plate 612 of the first bracket 610. As a result, the first bracket 610 can be disposed inside the second bracket 620 as illustrated in
Further, in certain embodiments, the concave brace 700 (
In another preferred embodiment, the concave brace 700 comprises four arms: a first arm 704, a second arm 706, a third arm 708, and a fourth arm 710. The arm 704 and the arm 708 have a first radius of curvature about a vertical z-axis 712. Similarly, the arm 706 and the arm 710 have a second radius of curvature about the z-axis 712. Further, the first and the second radii are substantially the same. The curvatures of the concave brace 700 reduces the bowing extension of the reflector 200 and the dome 320 after the entire panel antenna is mounted on a structure, especially under stress conditions.
Simulation Results
Applicant has tested different embodiments antennas described in the current disclosure. Table 1 below includes a non-exhaustive list of design parameters tested. During all the simulation tests, the panel antenna 100 is mounted to any structure in a way that a diagonal line 740 (
Referring to
Various physical antenna parameters may be changed an optimized to achieve various performance characteristics over various frequency ranges. It has been observed by applicants that, over the preferred frequency range of 698-940 MHz, it is helpful to vary the spacing of the dipole elements, and the height of the reflector walls, to achieve an optimum mix of F/B ratio, forward gain, and minimization of side lobe gain. In general terms, dipole elements must be sufficiently far away from the sidewall reflectors to avoid fringing effects and leakage, but they must not be closely packed so as to decrease the effective aperture of the reflector, which would decrease overall gain. The parameters reflected in the third column of Table 1 (240 mm element spacing, 152 mm length dipole, 3×3 array, 60 mm reflector sidewall height of a 700 mm×700 mm reflector) represent one advantageous embodiment, but other mixes of parameters are possible depending on design goals.
It will be appreciated by those skilled in the art that while the invention has been described above in connection with particular embodiments and examples, the invention is not necessarily so limited, and that numerous other embodiments, examples, uses, modifications and departures from the embodiments, examples and uses are intended to be encompassed by the claims attached hereto. Various features and advantages of the invention are set forth in the following claims.
This Application claims priority to U.S. Provisional Patent Application 62/396,061, filed on Sep. 16, 2016, the disclosure of which is incorporated herein in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 62396061 | Sep 2016 | US |
