Patent Application
20160172732
The present disclosure relates generally to antennas and, in particular, to wave guide polarizers for antennas. Still more particularly, the present disclosure relates to circular polarizers for antennas.
A phased array antenna is a group of antennas in which the relative phases of the respective signals feeding the antennas may be varied in a way that the effect of radiation pattern of the array is reinforced in a desired direction and suppressed in undesired directions. In other words, one or more beams may be generated that may be pointed in or steered into different directions. A beam pointing in a transmitting or receiving phased array antenna is achieved by controlling the phasing timing of the transmitted or received signal from each antenna element in the array.
The individual radiated signals are combined to form the constructive and destructive interference patterns of the array. A phased array antenna may be used to point one or more fixed beams or to scan one or more beams rapidly in azimuth or elevation.
Each antenna element in a phased array antenna may employ a polarizer. This polarizer converts a signal in a circular polarized form to a linearly polarized form or vice versa. Signals that are transmitted from an antenna may be converted from a linear polarized form to a circular polarized form for transmission. The conversion for an array receiving a signal is converted from circular to linear polarization. This conversion can be accomplished by these same devices. Further discussion is limited to the transmit case for brevity but inversely (conversion from circular to linear) also applies for the receive case. A polarizer may be placed within a waveguide and may be formed using different dielectric materials.
It is desirable to transform a linear polarized signal in a circular waveguide into a circular polarized signal in a manner with low loss, good matching, and a good fit within the cross section of the waveguide. Existing solutions for polarizers may involve a non-circular cross section in the waveguide to obtain the desired polarization of signals. These types of waveguides may require expensive manufacturing techniques. Further, these types of polarizers also may be more difficult to match.
Illustrative examples of the present disclosure include, without limitation, methods, structures, and systems. In one aspect, a circular dielectric polarizer can have a cylindrical shape and include a dielectric slab, a dielectric core, and at least one air cutouts portions of the dielectric core. The dielectric slab can include a first dielectric material and have a thickness centered about an axis of the cylindrical shape. The dielectric core can include a second dielectric material. Portions of the dielectric core can be located on different sides of the dielectric slab. The dielectric core and the dielectric slab can form the cylindrical shape. The dielectric constant of the first dielectric material can be higher than a dielectric constant of the second dielectric material. Parameters of the circular dielectric polarizer, the dielectric slab, the dielectric core, and the at least one air cutout are selected to obtain approximately a 90 degree difference in phase in a signal passing through the circular dielectric polarizer at a target frequency.
In one example, the air cutout can have a substantially uniform cross section throughout a length of the circular dielectric polarizer. The cross section can include an arc-shaped cross section with a constant radius. An air cutout in the first portion of the dielectric core and the second portion of the dielectric core can be located symmetrically about the axis of the circular dielectric polarizer.
In another example, the parameters of the circular dielectric polarizer, the dielectric slab, the dielectric core, and the at least one air cutout can include one or more of a thickness of the dielectric slab, a diameter of the circular dielectric polarizer, a length of the circular dielectric polarizer, a width of the at least one air cutout, and an air cutout diameter. In another example, the parameters of the circular dielectric polarizer, the dielectric slab, the dielectric core, and the at least one air cutout can include one or more of a dielectric constant of the first dielectric material and a dielectric constant of the second dielectric material.
In another example, the circular dielectric polarizer can also include a container located around the dielectric slab and the dielectric core. The container can be configured to hold the dielectric core and the dielectric slab in the cylindrical shape. The container can include a metal tube. In yet another example, the target frequency can be 44.5 GHz with a bandwidth of 2 GHz.
In another aspect, a circular dielectric polarizer can have a cylindrical shape and include a tapered dielectric slab and a dielectric core. The tapered dielectric slab can include a first dielectric material and have a thickness centered about an axis of the cylindrical shape. The tapered dielectric slab can include at least a first tapered side. The dielectric core can include a second dielectric material. A first portion of the dielectric core can be located on a first side of the tapered dielectric slab and a second portion of the dielectric core can be located on a second side of the tapered dielectric slab. The first portion of the dielectric core, the tapered dielectric slab and the second portion of the dielectric core can form the cylindrical shape. The dielectric constant of the first dielectric material can be higher than a dielectric constant of the second dielectric material. Parameters of the circular dielectric polarizer, the tapered dielectric slab, and the dielectric core can be selected to obtain approximately a 90 degree difference in phase in a signal passing through the circular dielectric polarizer at a target frequency.
In one example, the tapered dielectric slab can include a second tapered side. The first and second tapered sides can be symmetrical about the axis of the cylindrical shape. At least one portion of the dielectric core can include protrusions. The protrusions can be configured to fill at least one void of a taper of the tapered dielectric slab.
In another example, the parameters of the circular dielectric polarizer, the tapered dielectric slab and the dielectric core can include one or more of a thickness of the tapered dielectric slab, a diameter of the circular dielectric polarizer, a length of the circular dielectric polarizer, and a depth of a taper on the first tapered side. In another example, the parameters of the circular dielectric polarizer, the tapered dielectric slab and the dielectric core can include one or more of a dielectric constant of the first dielectric material and a dielectric constant of the second dielectric material.
In another example, the circular dielectric polarizer can also include a container located around the tapered dielectric slab and the dielectric core. The container can be configured to hold the first portion of the dielectric core, the tapered dielectric slab and the second portion of the dielectric core in the cylindrical shape. The container can include a metal tube.
Other features of the methods, structures, and systems are described below. The features, functions, and advantages can be achieved independently in various examples or may be combined in yet other examples, further details of which can be seen with reference to the following description and drawings.
Throughout the drawings, reference numbers may be re-used to indicate correspondence between referenced elements. The drawings are provided to illustrate examples described herein and are not intended to limit the scope of the disclosure.
With reference now to the figures and, in particular, with reference to
Control unit 106 controls the array pointing angle for antenna array 108. Antenna array 108 may be either a single- or multi-beam antenna. Antenna array 108 also may be a transmit antenna and/or receive antenna in these illustrative examples.
Control unit 106 takes data from antenna array 108 and sends that data to temperature readout 104 for presentation to an operator and for automatic power down features. In the different embodiments, antenna array 108 may employ circular polarizers according to one or more different embodiments.
With reference now to
Signal input 202 may receive a radio frequency (RF) signal for transmission. Phase shifter 204 performs phase shifting of signals in accordance with instructions from control unit 106 in
With reference now to
The different embodiments may be implemented in polarizer 300 to provide for polarization in a manner that may include low loss, good matching, and a good fit to a round cross section for antenna element 210. Antenna element 210 may receive a linear signal from coaxed waveguide interface 208. This linear signal can be described as two equal orthogonal vectors that, when summed together, equal the input linear signal. The linear signal may be circularly polarized by delaying one vector by around 90 degrees using polarizer 300. This delay may be referred to as shifting the vector relative to the other vector.
Referring now to
In
A number of factors may affect the performance of the circular dielectric polarizer 402, such as the width of the dielectric slab, the size or sizes of the one or more air cutouts, the type of dielectric material in the dielectric core 410, the type of dielectric material in the dielectric slab 412, the diameter of the circular dielectric polarizer 402, and the like. Each of these factors can be determined such that a phase shift occurs as signal 422 passes through circular dielectric polarizer 402. Signal 422 may have two equal orthogonal vectors. Signal 422 may be circular polarized by shifting one of these vectors by around 90 degrees. The phase shift obtained using the circular dielectric polarizer 402 can be about a 90 degree difference in phase as signal 422 passes through dielectric polarizer 402. The circular dielectric polarizer 402 can be used to convert a circular polarized signal to a linear polarized signal, and to convert a linear polarized signal to a circular polarized signal.
In some examples, the polarizer 400 may have a waveguide 436. The waveguide 436 may be in the form of a metal tube or any other form. The waveguide 436 may be formed as an integral part of the polarizer 400 so that a separate waveguide may not need to be used with polarizer 400. Such a design may reduce the weight and complexity for creating antenna elements.
Referring now to
In
A number of factors may affect the performance of the circular dielectric polarizer 502, such as the width of the tapered dielectric slab 516, the depth of the taper of the tapered dielectric slab 516, the type of dielectric material in the dielectric core 510, the type of dielectric material in the tapered dielectric slab 516, the diameter of the circular dielectric polarizer 502, and the like. Each of these factors can be determined such that a phase shift occurs as signal 522 passes through circular dielectric polarizer 502. Signal 522 may have two equal orthogonal vectors. Signal 522 may be circular polarized by shifting one of these vectors by around 90 degrees. The phase shift obtained using the circular dielectric polarizer 502 can be about a 90 degree difference in phase as signal 522 passes through dielectric polarizer 502. The circular dielectric polarizer 502 can be used to convert a circular polarized signal to a linear polarized signal, and to convert a linear polarized signal to a circular polarized signal.
In some examples, the polarizer 500 may have a waveguide 536. The waveguide 536 may be in the form of a metal tube or any other form. The waveguide 536 may be formed as an integral part of the polarizer 500 so that a separate waveguide may not need to be used with polarizer 500. Such a design may reduce the weight and complexity for creating antenna elements.
Referring now to
The dielectric core 602 can be in two parts, as shown in
The various parameters (e.g., sizes and materials) of the dielectric core 602, the dielectric slab 604, and the air cutouts 606 can be selected to tune the circular dielectric polarizer 600 to a particular frequency. For example, as the thickness 610 of the dielectric slab 604 increases, the slower the phase velocity of a signal passing through the dielectric slab 604. In another example, the greater the width 612 of the cutout 606 and/or the air cutout diameter 614 of the cutout 606, the lower the effective dielectric constant of the dielectric core 602. In another example, the greater the length 616 of the circular dielectric polarizer 600, the longer that signals will pass through the materials of the dielectric core 602 and the dielectric slab 604. In operation, a signal can be received via one end of the circular dielectric polarizer 600, the signal can pass through the circular dielectric polarizer 600, and the signal can be emitted from the other end of the circular dielectric polarizer 600. As the signal passes through the circular dielectric polarizer 600, the parameters of the circular dielectric polarizer 600, the dielectric slab 604, the dielectric core 602, and the air cutouts 606 cause approximately a 90 degree difference in phase of the signal.
In one particular example, the circular dielectric polarizer 600 can be tuned to a center frequency of 44.5 GHz with a bandwidth of 2 GHz. The dielectric core 602 can be made of a material with a dielectric constant of K=2.54 and a loss tangent of 0.0005. The dielectric slab 604 can be made of a material with a dielectric constant of K=4 and a loss tangent of 0.0005. The thickness 610 of the dielectric slab 604 can be 19.4 mils, the width 612 of the air cutouts 606 can be 51.2 mils, the diameter 608 of the circular dielectric polarizer 600 can be 114 mils, the air cutout diameter 614 between the air cutouts 606 can be 73.2 mils, and the circular dielectric polarizer 600 can have a length 616 of 242.5 mils.
In the embodiment shown in
Referring now to
The tapered dielectric slab 804 can have a width 812 that is centered about the axis of the circular dielectric polarizer 800. The tapered dielectric slab 804 can have two, symmetrical tapers 806. Each of the tapers 806 can come to a taper point 808. The taper point 808 can be a depth 814 inward from the edge of the circular dielectric polarizer 800. The area between the taper 806 and the edge of the circular dielectric polarizer 800 can be filled by the dielectric core 802. The tapers 806 of the tapered dielectric slab 804 can be linear, as shown in
The various parameters (e.g., sizes and materials) of the dielectric core 802 and the tapered dielectric slab 804 can be selected to tune the circular dielectric polarizer 800 to a particular frequency. For example, as the width 812 of the tapered dielectric slab 804 increases, the slower the phase velocity of a signal passing through the tapered dielectric slab 804. In another example, the deeper the depth 814 of the taper 806, the faster the phase velocity of a signal passing through the tapered dielectric slab 804. In another example, the greater the length 816 of the circular dielectric polarizer 800, the longer that signals will pass through the materials of the dielectric core 802 and the dielectric slab 804.
In one particular example, the circular dielectric polarizer 800 can be tuned to a center frequency of 44.5 GHz with a bandwidth of 2 GHz. The dielectric core 802 can be made of a material with a dielectric constant of K=2.54 and a loss tangent of 0.0005. The tapered dielectric slab 804 can be made of a material with a dielectric constant of K=5.4 and a loss tangent of 0.0005. The width 812 of the tapered dielectric slab 804 can be 20.5 mils, the depth 814 of the tapers 806 can be 15.8 mils, the diameter 810 of the circular dielectric polarizer 90 can be 114 mils, and the circular dielectric polarizer 800 can have a length 816 of 289 mils.
In the embodiment shown in
Conditional language used herein, such as, among others, “can,” “could,” “might,” “may,” “e.g.,” and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain examples include, while other examples do not include, certain features, elements, and/or steps. Thus, such conditional language is not generally intended to imply that features, elements and/or steps are in any way required for one or more examples or that one or more examples necessarily include logic for deciding, with or without author input or prompting, whether these features, elements and/or steps are included or are to be performed in any particular example. The terms “comprising,” “including,” “having,” and the like are synonymous and are used inclusively, in an open-ended fashion, and do not exclude additional elements, features, acts, operations, and so forth. Also, the term “or” is used in its inclusive sense (and not in its exclusive sense) so that when used, for example, to connect a list of elements, the term “or” means one, some, or all of the elements in the list.
In general, the various features and processes described above may be used independently of one another, or may be combined in different ways. All possible combinations and subcombinations are intended to fall within the scope of this disclosure. In addition, certain method or process blocks may be omitted in some implementations. The methods and processes described herein are also not limited to any particular sequence, and the blocks or states relating thereto can be performed in other sequences that are appropriate. For example, described blocks or states may be performed in an order other than that specifically disclosed, or multiple blocks or states may be combined in a single block or state. The example blocks or states may be performed in serial, in parallel, or in some other manner. Blocks or states may be added to or removed from the disclosed examples. The example systems and components described herein may be configured differently than described. For example, elements may be added to, removed from, or rearranged compared to the disclosed examples.
While certain example or illustrative examples have been described, these examples have been presented by way of example only, and are not intended to limit the scope of the inventions disclosed herein. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of certain of the inventions disclosed herein.
