Patent Application
20250112377
The present application claims the benefit of priority to Chinese Patent Application No. 202210493918.9, filed on Apr. 29, 2022, with the China National Intellectual Property Administration, and the entire contents of the above-identified application are incorporated by reference as if set forth herein.
The present disclosure relates generally to microwave communication and, more particularly, to microwave antenna systems.
Microwave transmission refers to the transmission of information or energy by electromagnetic waves whose wavelengths are measured in units of centimeters. These electromagnetic waves are called microwaves. The “microwave” portion of the radio spectrum ranges across a frequency band of approximately 1.0 GHz to approximately 300 GHz. These frequencies correspond to wavelengths in a range of approximately 30 centimeters to 0.1 centimeters.
Microwave communication systems may be used for point-to-point communications because the small wavelength of the electromagnetic waves may allow relatively small sized antennas to direct the electromagnetic waves into narrow beams, which may be pointed directly at a receiving antenna. This ability to form narrow antenna beams may allow nearby microwave communications equipment to use the same frequencies without interfering with each other as might occur in lower frequency electromagnetic wave communication systems. In addition, the high frequency of microwaves may give the microwave band a relatively large capacity for carrying information, as the microwave band has a bandwidth approximately thirty times the bandwidth of the entirety of the radio spectrum that is at frequencies below the microwave band. Microwave communications systems, however, are limited to line of sight propagation as electromagnetic waves at microwave frequencies cannot pass around hills, mountains, structures, or other obstacles in the way that lower frequency radio waves can.
Parabolic reflector antennas are often used to transmit and receive microwave signals.
The hub 50 may be used to mount the parabolic reflector antenna 20 on a mounting structure (not shown) such as a pole, antenna tower, building or the like. The hub 50 may be mounted on the rear surface of the parabolic reflector antenna 20 by, for example, mounting screws. The hub 50 may include a hub adapter 52. The hub adapter 52 may be received within the feed bore 22.
The feed assembly 30 may include a waveguide boom 32, a sub-reflector 40, a low-loss dielectric block 34, and a transition element 54. The transition element 54 may be within the hub adapter 52. The transition element 54 may be designed to efficiently launch RF signals received from, for example, a radio (not shown) into the other components of the feed assembly 30. For example, the transition element 54 may comprise a waveguide transition (e.g., a rectangular-to-circular transition) that is impedance matched for a specific frequency band.
The transition element 54 includes a bore 56 that receives the waveguide boom 32. The waveguide boom 32 may have a waveguide therein (e.g., a waveguide having a circular cross-sectional shape) and may be substantially tubular. The waveguide boom 32 may be formed of a metal such as, for example, aluminum. When the waveguide boom 32 is mounted in the hub adapter 52 and the hub adapter 52 is received within the feed bore 22, a base of the waveguide boom 32 may be proximal to the feed bore 22, and a distal end of the waveguide boom 32 may be in the interior of the parabolic reflector antenna 20.
The low-loss dielectric block 34 may be inserted into the distal end of the waveguide 32. The inserted end of the low-loss dielectric block 34 may have, for example, a stepped generally cone-like shape. The sub-reflector 40 may be mounted on the distal end of the dielectric block 34. In some cases, the sub-reflector 40 may be a metal layer that is sprayed, brushed, plated, or otherwise formed on a surface of the dielectric block 34. In other cases, the sub-reflector 40 may comprise a separate element that is attached to the dielectric block 34. The sub-reflector 40 is typically made of metal and is positioned at a focal point of the parabolic reflector antenna 20. The sub-reflector 40 is designed to reflect microwave energy emitted from the waveguide boom 32 onto the interior of the parabolic reflector antenna 20, and to reflect and focus microwave energy that is incident on the parabolic reflector antenna 20 into the distal end of the waveguide boom 32.
Some aspects of the present disclosure provide microwave antenna assemblies. For example, a microwave antenna assembly may include a waveguide that includes a first waveguide component and a second waveguide component; and a mechanical connection configured to couple the first waveguide component and the second waveguide component and configured to force a first gap between the first waveguide component and the second waveguide component. A spanning distance of the first gap may be selected to reduce a size of a second gap due to tolerances within the microwave antenna assembly between the waveguide and radio equipment. The radio equipment may be configured to provide the waveguide with microwave radiofrequency (RF) signals.
Another example of a microwave antenna assembly provided herein may include a waveguide arrangeable between radio equipment and a parabolic reflector antenna, where the waveguide includes a first waveguide portion and a second waveguide portion; a first gap between the first waveguide portion and the second waveguide portion; and a first radiofrequency (RF) choke concentric with the first gap. A spanning distance of the first gap may be selected to reduce a size of a second gap due to tolerances within the microwave antenna assembly in a direction of signal propagation.
Another example of a microwave antenna assembly provided herein may include a waveguide boom arrangeable between radio equipment and a parabolic reflector antenna; a first gap between the waveguide boom and a waveguide component different than the waveguide boom; and a first radiofrequency (RF) choke concentric with the first gap, where the first RF choke is at an undercut region formed in an end of the waveguide boom.
Some aspects of the present disclosure provide methods of using and/or assembling microwave antenna equipment, antenna equipment, and/or microwave antenna assemblies. For example a method may include: providing a plurality of components that form a waveguide between an antenna and radio equipment, each component having a tolerance associated therewith, the tolerances summing to a total tolerance stack; and forcing, via a mechanical connection, a gap between first and second components of the plurality components, wherein a location and a spanning distance of the gap are selected to divide the total tolerance stack into a first tolerance stack and a second tolerance stack.
The present disclosure is not limited to those aspects provided above, and other aspects will be apparent in view of the description of the inventive concepts provided herein and the accompanying drawings.
The microwave source 70 may be or may include one or more radios. In some embodiments, the microwave source 70 may include additional elements such as, for example, an orthomode transducer (“OMT”) that connects a pair of radios that transmit orthogonally polarized signals to the coaxial feed assembly. An interface port 72 of the microwave source 70 may be aligned coaxially with the interface port 58 of the transition element 56.
Ideally, to avoid performance loss in the transmission of signals between the microwave source 70 and the transition element 56, the components would be butted together with perfect or near-perfect ohmic contact, resulting in at most negligible reflections and negligible signal leakage. However, such an ohmic contact would require alignment and surface contact that would be both difficult to achieve and maintain in real-world conditions. For example, the microwave equipment of
To avoid damage to the microwave source 70 and/or the components of the microwave antenna system 10, there may be a site or customer requirement that there be no hard contact or flush mounting between the microwave source 70 and the hub adapter 52. In other words, to avoid damage, the mounting elements 60 may be configured to produce an unavoidable gap G between the interface port 72 of the microwave source 70 and the interface port 58 of the transition element 54. This unavoidable gap G, if sufficiently large, may result in degraded performance of the microwave system, for example due to microwave signals from the microwave source 70 not being received at the port 58, and instead propagating into free space. In contrast, the transition element 56, waveguide boom 32, and dielectric block 34 are typically manufactured to have no gaps and direct abutment therebetween to improve performance of the coaxial feed assembly.
Managing and designing microwave systems with a sufficiently small unavoidable gap G that nevertheless have acceptable microwave performance is made difficult in part due to two complications. A first complication is the concept of tolerance, which is present in all real-world mechanical structures. Tolerance recognizes that there may be some deviation in a dimension, property, or condition of a component resulting from manufacturing processes. For example, each component of the coaxial feed assembly 30 (e.g., the transition element 54, the waveguide boom 32, the low-loss dielectric block 34) may have a specified linear length Xi in a first direction that is parallel with the direction of microwave communication. In addition, each component may have a stated tolerance Yi that the component may deviate from the specified length while still being compliant with the specification. In other words, the length of the waveguide boom 32 in compliance with a specification thereof may be in the range X2+/−Y2. Waveguide booms 32 having lengths outside this specified range are not in compliance with the specified length. The tightness of the tolerance may be increased, and the size of the range (i.e., the value of Y) may be reduced, albeit typically at increased cost or complexity in manufacturing or at an increased rejection rate of manufactured components.
A second complication, related to tolerance, is that of tolerance stackup, or a cumulation or sum of the tolerances Yi in the first direction. Stated differently, each of the tolerances Yi shown in
It is known to use flanges having choke arrangements at waveguide joints, as discussed in U.S. Pat. No. 7,592,887 the entire content of which is incorporated herein by reference. For example, a circular groove (which can be formed, for example, in the back face of the hub adapter 52), having both a depth and a radius of a quarter wavelength (i.e., λ/4) may be coaxial with the interface port 58. Such a groove acts as an RF choke to cancel signals via destructive interference, thereby improving RF performance. However, when the size of the gap G is sufficiently large, or if during design it becomes evident that the gap G may be sufficiently large in view of the cumulative tolerance, a single groove may be insufficient. Thus, one or more additional grooves having a larger radius (e.g., three-quarter wavelengths (i.e., 3λ/4)) may be used. This results in an increase in both the manufacturing complexity of the component, as well as an increase in the overall size of the transition element 54 to accommodate the additional choke
The present disclosure is based on the recognition that, rather than providing these additional chokes at the gap G, one way to reduce the size of the gap G may be to split up the gap into multiple smaller gaps throughout the coaxial feed assembly. Each gap may accommodate a portion of the tolerance stack up. While more than one gap is provided, the size of the gaps may be reduced. If provided in a controlled manner, such smaller gaps may improve performance of the microwave antenna system, because the cumulative degradation to RF performance caused by the smaller gaps may be less than the degradation in RF performance caused by one large gap.
The transition element 154 may include a bore 156 that receives the waveguide boom 132. The waveguide boom 132 may have at least two components or sections 132-1 and 132-2 that are coupled together via mounting components 161. The waveguide boom 132 may have, for example, a circular cross-sectional shape and be substantially tubular. The waveguide boom 132 may be formed of a metal such as, for example, aluminum. When the waveguide boom 132 or a section thereof is mounted in the hub adapter 152 and the hub adapter 152 is received within the feed bore, a base of the waveguide boom 132 may be proximal the feed bore, and a distal end of the waveguide boom 132 may be in the interior of the parabolic reflector antenna. The dielectric block 134 may be coupled to or inserted into the waveguide boom 132 in a manner similar to that discussed above.
In contrast to
Coaxial chokes 133 may be provided in the first section 132-1 of the waveguide boom 132, the second section 132-2 of the waveguide boom 132, and/or the transition element 152. As described above, the coaxial chokes 133 may be grooves having a size and a depth corresponding to the wavelength of a transmission frequency of the microwave system.
As can be seen from comparison of
The inventive concepts described above with reference to
The waveguide 242 may be segmented into a plurality of portions 242-1, 242-2, . . . , 242-N, due to gaps G1, G2, . . . , GN-1 between the components of the coaxial feed assembly 210. The spanning distances of each of the gaps G1, G2, . . . , GN-1 in the first direction (e.g., the direction of microwave signal propagation within the waveguide 242) may be selected to reduce a size of a gap GN that results from tolerances or from a cumulative tolerance within the microwave antenna assembly in a first direction. The gap GN is between the microwave source 70 and an end of the waveguide 242 proximal to the microwave source 70.
Each gap G1, G2, . . . , GN-1 may have one or more than one concentric or coaxial choke 233 present in either a first waveguide component 230 on a first side of the gap G1, G2, . . . , GN-1, and/or in a second waveguide component 230 on a second side of the gap G1, G2, . . . , GN-1. Each of the coaxial chokes 133 may be grooves having a size and a depth corresponding to the wavelength of a transmission frequency of the microwave antenna system.
Each gap 435 and 437 may have one or more than one coaxial choke 433 present in either a first waveguide component on a first side of the gap 435 or 437 and/or in a second waveguide component on a second side of the gap 435 or 437. Each of the coaxial chokes 433 may be grooves having a size and a depth corresponding to the wavelength of a transmission frequency of the microwave antenna system. As can be seen in
In view of the above, the performance of the microwave antenna system 410, because a size of the gap 437 may be reduced due to the presence of gaps 435. Stated differently, by splitting up the gap 437 into multiple smaller gaps 435 throughout the coaxial feed assembly 410, RF signal performance may be improved.
The terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated operations, elements, and/or components, but do not preclude the presence or addition of one or more other operations, elements, components, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Like reference numbers signify like elements throughout the description of the figures.
The thicknesses of elements in the drawings may be exaggerated for the sake of clarity. Further, it will be understood that when an element is referred to as being “on,” “coupled to” or “connected to” another element, the element may be formed directly on, coupled to or connected to the other element, or there may be one or more intervening elements therebetween.
Terms such as “top,” “bottom,” “upper,” “lower,” “above,” “below,” and the like are used herein to describe the relative positions of elements or features. For example, when an upper part of a drawing is referred to as a “top” and a lower part of a drawing is referred to as a “bottom” for the sake of convenience, in practice, the “top” may also be called a “bottom” and the “bottom” may also be a “top” without departing from the teachings of the inventive concept.
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. Thus, a first element could be termed a second element without departing from the teachings of the inventive concept.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this inventive concept belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and this specification and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
The description of the present disclosure has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the disclosure in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the disclosure. The aspects of the disclosure herein were chosen and described in order to best explain the principles of the disclosure and the practical application, and to enable others of ordinary skill in the art to understand the disclosure with various modifications as are suited to the particular use contemplated.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202210493918.9 | Apr 2022 | CN | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2023/066282 | 4/27/2023 | WO |
