Patent Application
20170062946
The present application relates to antenna systems and, more particularly, although not exclusively, to microwave antenna systems that have beam widths that may be varied.
Microwave antennas are used for transmission and reception of microwave electromagnetic-radiation signals. A microwave antenna will have a particular characteristic beam pattern. This beam pattern typically includes a main lobe. The dimensions of the main lobe define the beam width for the principle transmission/reception beam for the antenna. A typical beam pattern also includes a number of side lobes. These side lobes reduce the transmission efficiency (as they typically represent lost signal power), but generally do not significantly impact alignment of the microwave antenna. The beam width of the main lobe—which is typically measured in terms of the angle subtended by the main lobe—is inversely proportional to the frequency of the signals transmitted by the antenna and to the effective size of the antenna. In other words, (a) the higher the operating frequency, the narrower the beam width, and (b) the larger the antenna, the narrower the beam width.
A microwave transmission link comprises a pair of distant antennas, namely a first antenna that transmits a microwave signal and a second antenna that receives the microwave signal. A thin—in other words, narrow or pencil—beam between the two antennas is more useful than a fat—in other words, wide—beam for efficiently transmitting signals between those two antennas since much more of the signal energy is directed from the transmitter to the receiver with a thin beam than with a fat beam. When setting up the two antennas for the transmission link, however, using a thin beam is more challenging than using a fat beam for alignment of the boresights of the respective antennas since a thin beam is more difficult to acquire and pinpoint than a fat beam.
Pursuant to embodiments of the present invention, methods of operating microwave antenna systems that include a microwave antenna are provided. Pursuant to these methods, the microwave antenna is operated in a first operating state during an alignment operation for the microwave antenna system where the microwave antenna is configured to have a first beam width. Subsequent to the alignment operation, the microwave antenna is operated in a second operating state where the microwave antenna is configured to have a second beam width that is narrower than the first beam width.
In some embodiments, the microwave antenna may comprise a flat panel array that has a plurality of antenna elements. A first subset of the antenna elements are used when the microwave antenna is operating in the first operating state and a second subset of the antenna elements are used when the microwave antenna is operating in the second operating state. The second subset of the antenna elements includes more antenna elements than the first subset of the antenna elements. For example, the second subset of the antenna elements may include all of the antenna elements.
In some embodiments, the microwave antenna may comprise a central reflector and the microwave antenna system may comprise the central reflector and a ring that circumferentially surrounds the central reflector. The first beam width may correspond to a beam width of a beam formed by the central reflector, and the second beam width may correspond to a beam width of a beam formed by the combination of the central reflector and the ring. The ring may comprise, for example, a plurality of petals that extend radially outwardly from the central reflector. The petals may be foldable petals. The ring may be removably attached to the central reflector.
In some embodiments, the microwave antenna may comprise a reflector antenna and the microwave antenna system may comprise the reflector antenna and a polarizer that has a polarization region and a central opening. The polarization region of the polarizer may be configured to pass signals having a first polarization and may be configured to block signals having a second polarization that is orthogonal to the first polarization. A first signal that is transmitted through the microwave antenna during operation in the first operating state may have the second polarization. Consequently, the first beam width may correspond to a beam width of a signal transmitted through the central opening of the polarizer. A second signal that is transmitted through the microwave antenna during operation in the second operating state may have the first polarization. The polarizer may be a removable polarizer or a rotatable polarizer.
In some embodiments, a pointing direction of the microwave antenna while operating in the first operating state may be the same as a pointing direction of the microwave antenna while operating in the second operating state, and a frequency of a signal transmitted in the first operating state may be the same as a frequency of a signal transmitted in the second operating state.
In some embodiments, the microwave antenna system may comprise the microwave antenna and a removable microwave lens. The removable microwave lens may be mounted on the microwave antenna when the microwave antenna is operating in the first operating state and may be removed from the microwave antenna when the microwave antenna is operating in the second operating state.
In some embodiments, the microwave antenna may comprise an elliptical reflector antenna, where the elliptical reflector antenna is positioned at a first orientation when the microwave antenna is operating in the first operating state and is positioned at a second, different, orientation when the microwave antenna is operating in the second operating state.
In some embodiments, the microwave antenna may comprise a reflector antenna, a feed and a blinker. The blinker may be placed over an end of the feed when the microwave antenna is operating in the first operating state and the blinker may be removed when the microwave antenna is operating in the second operating state.
In some embodiments, the microwave antenna may comprise a reflector antenna having a movable feed system, where the movable feed system is at a first position when the microwave antenna is operating in the first operating state and is at a second, different, position when the microwave antenna is operating in the second operating state.
In some embodiments, the microwave antenna may comprise a reflector antenna having a waveguide tube that has a mouth and a sub-reflector, where the sub-reflector is positioned away from the mouth when the microwave antenna is operating in the first operating state and is positioned atop the mouth when the microwave antenna is operating in the second operating state.
Pursuant to further embodiments of the present invention, methods of operating microwave antenna systems are provided. Pursuant to these methods, a microwave antenna is used to generate a first antenna beam having a first beam width when the microwave antenna system is operating in a first operating state, and the microwave antenna is used to generate a second antenna beam having a second beam width when the microwave antenna is operating in a second operating state. The second beam width is narrower than the first beam width.
In some embodiments, a pointing direction of the microwave antenna while operating in the first operating state may be the same as a pointing direction of the microwave antenna while operating in the second operating state, and a frequency of a signal transmitted in the first operating state may be the same as a frequency of a signal transmitted in the second operating state. In some embodiments, the microwave antenna may comprise a reflector antenna and one of a polarizer having a central opening, a microwave lens, a ring that circumferentially surrounds the reflector antenna, a laterally movable feed, a feed with a removable blinker or a feed with a removable or repositionable sub-reflector. In other embodiments, the microwave antenna may comprise a flat panel array having a plurality of antenna elements, and a first subset of the antenna elements are used when the microwave antenna is operating in the first operating state and a second subset of the antenna elements are used when the microwave antenna is operating in the second operating state, where the second subset of the antenna elements includes more antenna elements than the first subset of the antenna elements.
Pursuant to still further embodiments of the present invention, microwave antenna systems are provided that include a microwave antenna that is configured to have a first aperture size when operating in a first operating state during an alignment operation for the microwave antenna system and a second aperture size when operating in a second operating state subsequent to completion of the alignment operation, where the second aperture size exceeds the first aperture size.
Pursuant to embodiments of the present invention, microwave antenna systems are provided that can operate in at least first and second operating states where the microwave antenna has different beam widths. When operating in the first operating state, the microwave antenna system may be configured so that a microwave antenna thereof will have a relatively wide beam width. The microwave antenna may be operating in the first operating state when the microwave antenna is being physically aligned to point at a distant antenna. The use of the wider beam width antenna beam may make it easier to align the antenna to point at the distant antenna. Once the antenna is properly aligned to point in a desired direction, the microwave antenna may be configured to operate in the second operating state that has the narrower beam width. The narrower beam width may have a higher gain and hence provide for improved transmission efficiency.
An antenna whose beam width may be varied allows the use of (i) a wider beam during the setup or reconfiguration of a communication link to align the boresights of the respective antennas and (ii) a narrower beam during normal operation, after the setup, for more-efficient signal transmission. Typically, the active radio device that generates the signals that are fed to the microwave antenna for transmission operates at a fixed frequency. Consequently, the exemplary embodiments described below vary the beam width by varying the actual or effective size of the antenna while keeping the operating frequency fixed.
In an alternative implementation, the petals 24 are removably connected to the central reflector 20 with fasteners that allow for the rapid removal and re-attachment of the petals 24 to the central reflector 20. In another alternative implementation, microwave antenna system 10 is aligned with a distant antenna with only the central reflector 20 in place and, subsequently, the petals 24 are fixedly or removably attached to the central reflector 20 for regular operation. Fixed attachment refers to an attachment that does not allow for a rapid removal—for example, using screws, bolts, glue, or solder. In another alternative implementation, the entire ring formed by all of the petals 24 together is removably attached, as a unitary ring, to the central reflector 20. In such embodiments, the ring may be a monolithic structure as opposed to a plurality of petals 24 that are attached together to form the unitary ring.
Microwave antenna system 100 is a flat-panel antenna comprising a 16×16 array of antenna elements 110. In the first operating state, shown in
The antenna array may have more or fewer than 256 elements and the sub-array may have fewer or more than 16 elements. Further note that the flat-panel antenna is not limited to a square shape and may be any other suitable shape, including, for example, triangle, rectangle, pentagon, hexagon, octagon, and circle.
In an alternative implementation, some antenna elements 110 may be inactive in the second operating state as long as more antenna elements 110 are active in the second operating state than are active in the first operating state. In one alternative implementation, the elements 110 of subarray 120 might not all be located substantially in the center of the array of flat panel microwave antenna system 100.
Similar to the microwave antenna system 100 of
In the first operating state, the microwave antenna system 200 generates beam 240, which has a relatively wide beam width, by using a suitable non-uniform excitation pattern 242—referred to as a taper pattern—for the antenna elements 210. Suitable taper patterns may, for example, include patterns in accordance with distributions such as Taylor, Dolph-Chebyshev, and Hansen. Note that the taper pattern 242 may vary (i) the phase but not the amplitude, (ii) the amplitude but not the phase, or (iii) both phase and amplitude of the elements 210.
In the second operating state, the microwave antenna system 200 generates beam 250, which has a relatively narrow beam width, by using a uniform excitation pattern 252 for the antenna elements 210. In other words, in the second operating state, all of the elements 210 transmit the signal at the same phase and amplitude. Note that the wide beam 240 and the narrow beam 250 have the same spatial orientation. Also note that the microwave antenna system 200 may have alternative implementations similar to the alternative implementations described above for the microwave antenna system 100 of
The microwave antenna system 300 is a dual-polarization antenna system adapted to transmit signals in either of two polarizations orthogonal to each other. Specifically, the microwave antenna system 300 is adapted to transmit a horizontally polarized signal 340 in a first operating state and a vertically polarized signal 350 in a second operating state. Note that the microwave antenna system 300 includes additional components (not shown) for the generation and transmission of the signals, such as, for example, a feed element.
Polarizing grille 360, a form of a wire-grid polarizer, comprises horizontal metallic lines 362 in the perimeter ring 364, which is the area between outer perimeter 366 and inner perimeter 368. Outer perimeter 366 substantially coincides with the periphery of the reflector 320. Inner perimeter 368 defines aperture 370, a metal-line-free area in the center of metal-lined ring 364. Horizontal metallic lines 362 substantially absorb, block, and/or reflect horizontally polarized electro-magnetic (EM) radiation, such as signal 340, while leaving substantially unaffected vertically polarized EM radiation, such as signal 350. Preferably, the horizontal metallic lines 362 are dimensioned and arrayed such that there are ten or more horizontal lines 362 per unit of wavelength of the signal transmitted by the microwave antenna system 300. For example, for a 10 GHz signal, whose wavelength is 3 cm, two adjacent metal lines 362 would be separated by less than a third of a centimeter.
In the first operating state, as shown in
Grille 360 may be formed by any suitable means. Metal lines 362 may be, for example, printed, glued, woven, embedded or otherwise fixed in or on a fiber, paper, polymer, or any suitable microwave-permeable substrate. Aperture 370 may comprise the substrate or may be open. In an alternative implementation, metal lines 362 may be suspended in air between corresponding attachment endpoints in rings corresponding to outer perimeter 366 and/or inner perimeter 368. The supporting rings may be metallic or insulating. Preferably, the inner ring, corresponding to inner perimeter 368, is non-conductive to minimize the impact on the radiation pattern of the beams 372 and 374. In alternative embodiments, the microwave antenna system 300 may generate signals polarized in two orthogonal directions other than horizontal and vertical, where the orientation of metal lines 362 is correspondingly adjusted to be parallel to the signal in the first operating state.
In a first operating state, as shown in
In a first operational state, as shown in
In the first operating state, lens 660 of
In some alternative embodiments of antenna system 600, the lens 660 is a polarized lens that affects only radiation polarized in a particular direction. In one implementation, the antenna system 600 generates a signal polarized in the first direction and the lens 660 is rotated or repositioned to generate either a narrow beam—when the lens 660 does not significantly affect the signal generated—or a wide beam—when the lens 660 diverges the signal generated. In another implementations, the lens 660 remains stationary and in place, but the antenna system 600 is configured to generate one of two differently polarized signals, where one is not significantly affected by the lens 660 and the other is refracted to diverge by the lens 660.
It should be noted that, in alternative implementations, the orientations of the signals (not shown) generated by the antenna system 800 may be polarized vertically, horizontally, or in any other suitable direction. It should also be noted that, in alternative implementations, the reflector 820 may have a non-circular shape other than elliptical where, depending on orientation, beams of different widths would result from the same signal.
Embodiments of the disclosure have been described that use ring-shaped grilles as polarizing rings, where the polarizing ring allows passage of microwaves oriented in one direction and blocks passage of microwaves oriented in any other direction. It should be noted, however, that polarizing rings are not limited to metallic grilles. In some alternative embodiments, an alternative polarizing ring may be used, which polarizes microwaves by means other than parallel metal lines.
Embodiments of the disclosure have been described where the antennas are generating signals for transmission. It should be noted, however, that the embodiments are equally applicable for receiving antennas, which may similarly operate in two states for reception, where the antenna has a wide-beam reception in a first operating state and a narrow-beam reception in a second operating state.
Embodiments of the present invention have been described above with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, the embodiments disclosed above 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 numbers refer to like elements throughout.
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, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present invention. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
It will be understood that when an element is referred to as being “on” or “connected to” another element, it can be directly on or connected to the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” or “directly connected to” another element, there are no intervening elements present. Other words used to describe the relationship between elements should be interpreted in a like fashion (i.e., “between” versus “directly between”, “adjacent” versus “directly adjacent”, etc.).
Relative terms such as “below” or “above” or “upper” or “lower” or “horizontal” or “vertical” may be used herein to describe a relationship of one element, layer or region to another element, layer or region as illustrated in the figures. It will be understood that these terms are intended to encompass different orientations of the device in addition to the orientation depicted in the figures.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. 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” “comprising,” “includes” and/or “including” when used herein, 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.
In the drawings and specification, there have been disclosed typical embodiments of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention being set forth in the following claims.
This application claims priority under 35 U.S.C. §119 from U.S. Provisional Patent Application Ser. No. 62/212,184, filed on Aug. 31, 2015, the disclosure of which is hereby incorporated by reference herein as if set forth in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 62212184 | Aug 2015 | US |
