Patent Application
20150276926
If an Application Data Sheet (ADS) has been filed on the filing date of this application, it is incorporated by reference herein. Any applications claimed on the ADS for priority under 35 U.S.C. §§119, 120, 121, or 365(c), and any and all parent, grandparent, great-grandparent, etc. applications of such applications, are also incorporated by reference, including any priority claims made in those applications and any material incorporated by reference, to the extent such subject matter is not inconsistent herewith.
The present application claims the benefit of the earliest available effective filing date(s) from the following listed application(s) (the “Priority Applications”), if any, listed below (e.g., claims earliest available priority dates for other than provisional patent applications or claims benefits under 35 USC §119(e) for provisional patent applications, for any and all parent, grandparent, great-grandparent, etc. applications of the Priority Application(s)).
None.
If the listings of applications provided above are inconsistent with the listings provided via an ADS, it is the intent of the Applicant to claim priority to each application that appears in the Domestic Benefit/National Stage Information section of the ADS and to each application that appears in the Priority Applications section of this application.
All subject matter of the Priority Applications and of any and all applications related to the Priority Applications by priority claims (directly or indirectly), including any priority claims made and subject matter incorporated by reference therein as of the filing date of the instant application, is incorporated herein by reference to the extent such subject matter is not inconsistent herewith.
In one embodiment, an apparatus comprises: a scattering antenna having a first plurality of scattering elements, each of the scattering elements in the first plurality of scattering elements having an individual electromagnetic response to an incident electromagnetic wave, and wherein the scattering antenna is configured to produce a first radiation field responsive to the incident electromagnetic wave; a reflector antenna arranged to receive at least a portion of the first radiation field, the reflector antenna having a second plurality of scattering elements, wherein the reflector antenna is responsive to reflect a portion of the first radiation field to produce a second radiation field different from the first radiation field; and a detector configured to receive at least a portion of the second radiation field.
In another embodiment, an apparatus comprises: a source configured to produce an incident electromagnetic wave; a reflector antenna arranged to receive the incident electromagnetic wave, the reflector antenna having a first plurality of scattering elements, wherein the reflector antenna is responsive to reflect a portion of the incident electromagnetic wave to produce a first radiation field; and a scattering antenna configured to receive at least a portion of the first radiation field, the scattering antenna having a second plurality of scattering elements, each of the scattering elements in the second plurality of scattering elements having an individual electromagnetic response to an incident electromagnetic wave.
In another embodiment, a system comprises: a source configured to produce electromagnetic energy and operably connected to a scattering antenna to radiate the electromagnetic energy in a field of view; a reflector antenna arranged relative to the scattering antenna to receive the electromagnetic energy and to produce a set of beam patterns in the field of view, the set of beam patterns being at least partially determined by at least one of a set of scattering antenna patterns, a set of reflector antenna patterns, and a set of frequencies of the electromagnetic energy produced by the source; a detector configured to receive electromagnetic energy from the set of beam patterns; and circuitry coupled to the detector and configured to reconstruct an image of a scene within the field of view using a compressive imaging algorithm based on the set of beam patterns.
In another embodiment, a method comprises: producing a first series of radiation fields; reflecting at least a portion of the first series of radiation fields to produce a second series of radiation fields different from the first series of radiation fields; reflecting at least a portion of the first series of radiation fields to produce a second series of radiation fields different from the first series of radiation fields; detecting at least a portion of each radiation field in the second series of radiation fields; and reconstructing an image of a scene that is illuminated by the first and second series of radiation fields using a compressive imaging algorithm.
The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.
In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented here.
In the embodiment in
A portion of the first radiation field 118 is then received by the reflector antenna 104 having scattering elements 116, which re-radiates a portion of the energy to produce the second radiation field 119. The first and second radiation fields 118, 119 combine to form a beam pattern 120 in the location of an object 108 to be imaged. The beam pattern 120 depends on many factors, including but not limited to: the frequency of the electromagnetic energy, the pattern of the scattering elements 112 in the scattering antenna 102, the pattern of the scattering elements 116 in the reflector antenna 104, and the physical locations of each of the scattering elements 112, 116 in the scattering antenna 102 and the reflector antenna 104, which may be determined by the relative positions and orientations of the scattering antenna 102 and the reflector antenna 104. As is described in Bily1, Bily2, and Bowers, the scattering elements 112, 116 may in some embodiments be adjustable such that the first and second radiation fields 118, 119 are adjustable, and therefore the beam pattern 120 is adjustable responsive to the adjustment(s) to the scattering elements 112, 116.
The system further comprises a detector 122 that is configured to receive electromagnetic energy, where in
As described above, the beam pattern 120 is variable according to a number of factors. The circuitry 106 is configured with a compressive imaging algorithm (compressive imaging systems that incorporate surface scattering antennas were described in Smith1) to produce an image of an object 108 by determining a signal from the detector 122 for a known set of beam patterns 120.
In some embodiments the waveguide 110 is configured to allow a discrete set of modes to propagate, wherein each mode in the discrete set of modes corresponds to a frequency. Each mode may then correspond to first and second radiation fields 118, 119.
In some embodiments the circuitry 106 may be operably connected to one or more elements of the system in order to change the beam pattern 120. For example, the beam pattern 120 may be varied by varying the frequency of the electromagnetic energy, and the source 114 may be operably connected to the circuitry 106 to receive a signal to vary the frequency of the electromagnetic energy produced by the source 114. Further, the beam pattern 120 may be varied according to the configuration of the scattering elements 112 in the scattering antenna 102. This is explained in detail in Bily1. In such an embodiment, the circuitry 106 may be operably connected to the scattering antenna 102 to change the configuration of the scattering elements 102. Further, the beam pattern 120 may be varied according to the configuration of the scattering elements 116 in the reflector antenna 104. This is explained in detail in Bowers. In such an embodiment, the circuitry 106 may be operably connected to the reflector antenna 104 to change the configuration of the scattering elements 116. The scattering antenna 102 and the reflector antenna 104 each has a position and an orientation, and the relative position and orientation of each of these antennas with respect to the other can also change the beam pattern. In some embodiments the scattering antenna 102 and/or the reflector antenna 104 may be mounted on a moveable device such that the relative position and/or orientation of the antennas may be varied, and in such an embodiment the circuitry may be operably connected to control the position(s) and/or the orientation(s) of one or more of the antennas. Further, the beam pattern can be changed by changing more than one of the above described parameters. For example, the frequency of the electromagnetic energy and the configuration of the scattering elements in the scattering antenna 102 may be changed.
The frequency range of the electromagnetic energy may depend on the particular application, and may, for example, include RF frequencies and/or millimeter wave frequencies.
In one embodiment, the scattering antenna 102 may be replaced by another reflector antenna 104, as shown in
Similar to what was described for
Although the embodiments in
A schematic illustration of a surface scattering reflector antenna 400 is depicted in
The surface scattering reflector antenna 400 may also include a component 406 configured to produce the incident electromagnetic wave 408. The component 406 may be an antenna such as a dipole and/or monopole antenna.
When illuminated with the component 406, the surface scattering reflector antenna 400 produces beam patterns dependent on the pattern formed by the scattering elements 402a, 402b and the frequency and/or wave vector of the radiation. The scattering elements 402a, 402b each have an adjustable individual electromagnetic response that is dynamically adjustable such that the reflected beam pattern is adjustable responsive to changes in the electromagnetic response of the elements 402a, 402b. In some embodiments the scattering elements 402a, 402b include metamaterial elements that are analogous to the adjustable complementary metamaterial elements described in Bily1, previously cited.
The scattering elements 402a, 402b are adjustable scattering elements having electromagnetic properties that are adjustable in response to one or more external inputs. Various embodiments of adjustable scattering elements are described, for example, in D. R. Smith et al., “Metamaterials for surfaces and waveguides”, U.S. Patent Application Publication No. 2010/0156573, which is incorporated herein by reference, and in Bily1, and further in this disclosure. Adjustable scattering elements can include elements that are adjustable in response to voltage inputs (e.g. bias voltages for active elements (such as varactors, transistors, diodes) or for elements that incorporate tunable dielectric materials (such as ferroelectrics)), current inputs (e.g. direct injection of charge carriers into active elements), optical inputs (e.g. illumination of a photoactive material), field inputs (e.g. magnetic fields for elements that include nonlinear magnetic materials), mechanical inputs (e.g. MEMS, actuators, hydraulics), etc. In the schematic example of
In the example of
The emergence of the plane wave 410 may be understood by regarding the particular pattern of adjustment of the scattering elements (e.g. an alternating arrangement of the first and second scattering elements in
Because the spatial resolution of the interference pattern is limited by the spatial resolution of the scattering elements, the scattering elements may be arranged along the substrate 404 with inter-element spacings that are much less than a free-space wavelength corresponding to an operating frequency of the device (for example, less than one-third or one-fourth of this free-space wavelength). In some approaches, the operating frequency is a microwave frequency, selected from frequency bands such as Ka, Ku, and Q, corresponding to centimeter-scale free-space wavelengths. This length scale admits the fabrication of scattering elements using conventional printed circuit board technologies, as described below.
In some approaches, the surface scattering reflector antenna 400 includes a substantially one-dimensional arrangement of scattering elements, and the pattern of adjustment of this one-dimensional arrangement may provide, for example, a selected antenna radiation profile as a function of zenith angle (i.e. relative to a zenith direction that is parallel to the one-dimensional wave-propagating structure). In other approaches, the surface scattering reflector antenna includes a substantially two-dimensional arrangement of scattering elements, and the pattern of adjustment of this two-dimensional arrangement may provide, for example, a selected antenna radiation profile as a function of both zenith and azimuth angles (i.e. relative to a zenith direction that is perpendicular to the substrate 404).
In some approaches, the substrate 404 is a modular substrate 404 and a plurality of modular substrates may be assembled to compose a modular surface scattering antenna. For example, a plurality of substrates 404 may be assembled to produce a larger aperture having a larger number of scattering elements; and/or the plurality of substrates may be assembled as a three-dimensional structure (e.g. forming an A-frame structure, a pyramidal structure, a wine crate structure, or other multi-faceted structure).
In some applications of the modular approach, the number of modules to be assembled may be selected to achieve an aperture size providing a desired telecommunications data capacity and/or quality of service, and or a three-dimensional arrangement of the modules may be selected to reduce potential scan loss. Thus, for example, the modular assembly could comprise several modules mounted at various locations/orientations flush to the surface of a vehicle such as an aircraft, spacecraft, watercraft, ground vehicle, etc. The modules need not be contiguous. In these and other approaches, the substrate may have a substantially non-linear or substantially non-planar shape whereby to conform to a particular geometry, therefore providing a conformal surface scattering reflector antenna (conforming, for example, to the curved surface of a vehicle).
More generally, a surface scattering reflector antenna is a reconfigurable antenna that may be reconfigured by selecting a pattern of adjustment of the scattering elements so that a corresponding scattering of the incident electromagnetic wave 408 produces a desired output wave. Thus, embodiments of the surface scattering reflector antenna may provide a reconfigurable antenna that is adjustable to produce a desired output wave by adjusting a plurality of couplings.
In some approaches, the reconfigurable antenna is adjustable to provide a desired polarization state of the output wave. Suppose, for example that first and second subsets of the scattering elements provide electric field patterns that are substantially linearly polarized and substantially orthogonal (for example, the first and second subjects may be scattering elements that are perpendicularly oriented on a surface of the substrate 404). Then the antenna output wave EOM may be expressed as a sum of two linearly polarized components.
Accordingly, the polarization of the output wave may be controlled by adjusting the plurality of couplings, e.g. to provide an output wave with any desired polarization (e.g. linear, circular, or elliptical).
A CELC element such as that depicted in
Noting that the shaped aperture 506 also defines a conductor island 508 which is electrically disconnected from outer regions of the conductor layer 604, in some approaches the scattering element can be made adjustable by providing an adjustable material within and/or proximate to the shaped aperture 506 and subsequently applying a bias voltage between the conductor island 508 and the outer regions of the conductor layer 604. For example, as shown in
For a nematic phase liquid crystal, wherein the molecular orientation may be characterized by a director field, the material may provide a larger permittivity ∈1 for an electric field component that is parallel to the director and a smaller permittivity ∈2 for an electric field component that is perpendicular to the director. Applying a bias voltage introduces bias electric field lines that span the shaped aperture and the director tends to align parallel to these electric field lines (with the degree of alignment increasing with bias voltage). Because these bias electric field lines are substantially parallel to the electric field lines that are produced during a scattering excitation of the scattering element, the permittivity that is seen by the biased scattering element correspondingly tend towards ∈1 (i.e. with increasing bias voltage). On the other hand, the permittivity that is seen by the unbiased scattering element may depend on the unbiased configuration of the liquid crystal. When the unbiased liquid crystal is maximally disordered (i.e. with randomly oriented micro-domains), the unbiased scattering element may see an averaged permittivity ∈ave˜(∈1+∈2)/2. When the unbiased liquid crystal is maximally aligned perpendicular to the bias electric field lines (i.e. prior to the application of the bias electric field), the unbiased scattering element may see a permittivity as small as ∈2. Accordingly, for embodiments where it is desired to achieve a greater range of tuning of the permittivity that is seen by the scattering element, the unit cell 500 may include positionally-dependent alignment layer(s) disposed at the top and/or bottom surface of the liquid crystal layer 510, the positionally-dependent alignment layer(s) being configured to align the liquid crystal director in a direction substantially perpendicular to the bias electric field lines that correspond to an applied bias voltage. The alignment layer(s) may include, for example, polyimide layer(s) that are rubbed or otherwise patterned (e.g. by machining or photolithography) to introduce microscopic grooves that run parallel to the channels of the shaped aperture 506.
Alternatively or additionally, the unit cell may provide a first biasing that aligns the liquid crystal substantially perpendicular to the channels of the shaped aperture 506 (e.g. by introducing a bias voltage between the conductor island 508 and the outer regions of the conductor layer 604), and a second biasing that aligns the liquid crystal substantially parallel to the channels of the shaped aperture 506 (e.g. by introducing electrodes positioned above the outer regions of the conductor layer 604 at the four corners of the unit cell, and applying opposite voltages to the electrodes at adjacent corners); tuning of the scattering element may then be accomplished by, for example, alternating between the first biasing and the second biasing, or adjusting the relative strengths of the first and second biasings. Examples of types of liquid crystals that may be used are described in Bily1.
Turning now to approaches for providing a bias voltage between the conductor island 508 and the outer regions of the conductor layer 604, it is first noted that the outer regions of the conductor layer 604 extends contiguously from one unit cell to the next, so an electrical connection to the outer regions of the conductor layer 604 of every unit cell may be made by a single connection to this contiguous conductor. As for the conductor island 508,
The cross sectional shape of the complementary metamaterial element 504 shown in
In some approaches the control circuitry 704 includes circuitry configured to provide control inputs that correspond to a selected or desired radiation pattern. For example, the control circuitry 704 may store a set of configurations of the antenna, e.g. as a lookup table that maps a set of desired antenna radiation patterns (corresponding to various beam directions, beam widths, polarization states, etc. as described previously herein) to a corresponding set of values for the control input(s). This lookup table may be previously computed, e.g. by performing full-wave simulations of the antenna for a range of values of the control input(s) or by placing the antenna in a test environment and measuring the antenna radiation patterns corresponding to a range of values of the control input(s). In some approaches control circuitry may be configured to use this lookup table to calculate the control input(s) according to a regression analysis; for example, by interpolating values for the control input(s) between two antenna radiation patterns that are stored in the lookup table (e.g. to allow continuous beam steering when the lookup table only includes discrete increments of a beam steering angle). The control circuitry 704 may alternatively be configured to dynamically calculate the control input(s) corresponding to a selected or desired antenna radiation pattern, e.g. by, for example, computing a holographic pattern (as previously described herein). Further, the control circuitry 704 may be configured with one or more feedback loops configured to adjust parameters until a selected radiation pattern is achieved.
The foregoing detailed description has set forth various embodiments of the devices and/or processes via the use of block diagrams, flowcharts, and/or examples. Insofar as such block diagrams, flowcharts, and/or examples contain one or more functions and/or operations, it will be understood by those within the art that each function and/or operation within such block diagrams, flowcharts, or examples can be implemented, individually and/or collectively, by a wide range of hardware, software, firmware, or virtually any combination thereof. In one embodiment, several portions of the subject matter described herein may be implemented via Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), digital signal processors (DSPs), or other integrated formats. However, those skilled in the art will recognize that some aspects of the embodiments disclosed herein, in whole or in part, can be equivalently implemented in integrated circuits, as one or more computer programs running on one or more computers (e.g., as one or more programs running on one or more computer systems), as one or more programs running on one or more processors (e.g., as one or more programs running on one or more microprocessors), as firmware, or as virtually any combination thereof, and that designing the circuitry and/or writing the code for the software and or firmware would be well within the skill of one of skill in the art in light of this disclosure. In addition, those skilled in the art will appreciate that the mechanisms of the subject matter described herein are capable of being distributed as a program product in a variety of forms, and that an illustrative embodiment of the subject matter described herein applies regardless of the particular type of signal bearing medium used to actually carry out the distribution. Examples of a signal bearing medium include, but are not limited to, the following: a recordable type medium such as a floppy disk, a hard disk drive, a Compact Disc (CD), a Digital Video Disk (DVD), a digital tape, a computer memory, etc.; and a transmission type medium such as a digital and/or an analog communication medium (e.g., a fiber optic cable, a waveguide, a wired communications link, a wireless communication link (e.g., transmitter, receiver, transmission logic, reception logic, etc.), etc.).
In a general sense, those skilled in the art will recognize that the various embodiments described herein can be implemented, individually and/or collectively, by various types of electro-mechanical systems having a wide range of electrical components such as hardware, software, firmware, and/or virtually any combination thereof; and a wide range of components that may impart mechanical force or motion such as rigid bodies, spring or torsional bodies, hydraulics, electro-magnetically actuated devices, and/or virtually any combination thereof. Consequently, as used herein “electro-mechanical system” includes, but is not limited to, electrical circuitry operably coupled with a transducer (e.g., an actuator, a motor, a piezoelectric crystal, a Micro Electro Mechanical System (MEMS), etc.), electrical circuitry having at least one discrete electrical circuit, electrical circuitry having at least one integrated circuit, electrical circuitry having at least one application specific integrated circuit, electrical circuitry forming a general purpose computing device configured by a computer program (e.g., a general purpose computer configured by a computer program which at least partially carries out processes and/or devices described herein, or a microprocessor configured by a computer program which at least partially carries out processes and/or devices described herein), electrical circuitry forming a memory device (e.g., forms of memory (e.g., random access, flash, read only, etc.)), electrical circuitry forming a communications device (e.g., a modem, communications switch, optical-electrical equipment, etc.), and/or any non-electrical analog thereto, such as optical or other analogs. Those skilled in the art will also appreciate that examples of electro-mechanical systems include but are not limited to a variety of consumer electronics systems, medical devices, as well as other systems such as motorized transport systems, factory automation systems, security systems, and/or communication/computing systems. Those skilled in the art will recognize that electro-mechanical as used herein is not necessarily limited to a system that has both electrical and mechanical actuation except as context may dictate otherwise.
All of the above U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications and non-patent publications referred to in this specification and/or listed in any Application Data Sheet are incorporated herein by reference, to the extent not inconsistent herewith.
One skilled in the art will recognize that the herein described components (e.g., operations), devices, objects, and the discussion accompanying them are used as examples for the sake of conceptual clarity and that various configuration modifications are contemplated. Consequently, as used herein, the specific exemplars set forth and the accompanying discussion are intended to be representative of their more general classes. In general, use of any specific exemplar is intended to be representative of its class, and the non-inclusion of specific components (e.g., operations), devices, and objects should not be taken limiting.
With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations are not expressly set forth herein for sake of clarity.
While particular aspects of the present subject matter described herein have been shown and described, it will be apparent to those skilled in the art that, based upon the teachings herein, changes and modifications may be made without departing from the subject matter described herein and its broader aspects and, therefore, the appended claims are to encompass within their scope all such changes and modifications as are within the true spirit and scope of the subject matter described herein. It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to claims containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that typically a disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms unless context dictates otherwise. For example, the phrase “A or B” will be typically understood to include the possibilities of “A” or “B” or “A and B.”
With respect to the appended claims, those skilled in the art will appreciate that recited operations therein may generally be performed in any order. Also, although various operational flows are presented in a sequence(s), it should be understood that the various operations may be performed in other orders than those which are illustrated, or may be performed concurrently. Examples of such alternate orderings may include overlapping, interleaved, interrupted, reordered, incremental, preparatory, supplemental, simultaneous, reverse, or other variant orderings, unless context dictates otherwise. Furthermore, terms like “responsive to,” “related to,” or other past-tense adjectives are generally not intended to exclude such variants, unless context dictates otherwise.
While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.
