HK1187450B - Surface scattering antennas - Google Patents

Description

Surface scattering antenna

Cross Reference to Related Applications

This application is related to the following listed applications ("related applications") and claims benefit from the earliest available valid filing date of the following listed applications ("related applications") (e.g., claims the earliest available priority date other than provisional patent applications or claims benefit under 35USC § 119(e) for any and all parent applications, grandparent applications, great grandparent applications, etc. of the related applications). All subject matter including any priority claims related applications and any and all parent, grandparent and great-grandparent applications of related applications, etc. is incorporated herein by reference to the extent such subject matter is not inconsistent herewith.

Related applications:

for the purpose of satisfying USPTO non-statutory requirements, the present application constitutes a partial continuation of U.S. patent application No.61/455,171 entitled "SURFACE SCATTERING ANTENNAS" filed on 15.10.2010 by inventor natran kundz et al, which is currently pending or which grants the currently pending application the right to benefit from the filing date.

The united states patent office (USPTO) has published a computer program for the USPTO that requires a patent application to both reference the serial number of the parent application and to indicate a notification of the effect of the application as to whether it is a continuation, partial continuation, or divisional application of the parent application. Kunin, Benefit of price-Filed Application, USPTO official gazette, 3/18/2003. The applicant entity (hereinafter referred to as "applicant") has provided hereinabove specific references to applications to claim priority from those applications as regulated by the regulations. Applicants understand that regulations are clear in their specific cited language and do not require a serial number or any characteristic description, such as "continuation" or "partial continuation," in order to claim priority to U.S. patent applications. Nevertheless, the applicant understands that the computer program of the USPTO has some data input requirements, and therefore the applicant has provided indications of the relationship between the present application and its parent application as set forth above, but explicitly states that these indications should not be construed in any way as any type of comment and/or permission as to whether the present application contains any new subject matter other than that of its parent application.

Drawings

Fig. 1 is a schematic depiction of a surface scattering antenna.

Fig. 2A and 2B depict exemplary tuning patterns and corresponding beam patterns, respectively, for a surface scattering antenna.

Fig. 3A and 3B depict another exemplary tuning pattern and corresponding beam pattern, respectively, for a surface scattering antenna.

Fig. 4A and 4B depict another exemplary adjustment pattern and corresponding field pattern, respectively, for a surface scattering antenna.

Fig. 5 and 6 depict unit cells of a surface scattering antenna.

Fig. 7 depicts an example of a metamaterial element.

Figure 8 depicts a microstrip embodiment of a surface scattering antenna.

Fig. 9 depicts a coplanar waveguide embodiment of a surface scattering antenna.

Fig. 10 and 11 depict closed waveguide embodiments of surface scattering antennas.

Fig. 12 depicts a surface scattering antenna with direct addressing of scattering elements.

Fig. 13 depicts a surface scattering antenna with matrix addressing of scattering elements.

FIG. 14 depicts a system block diagram.

Fig. 15 and 16 depict flowcharts.

Detailed Description

In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, like reference numerals generally refer to like parts throughout the various views unless the context indicates otherwise. The exemplary embodiments illustrated in the detailed description, drawings, and claims are not intended 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 herein.

A schematic illustration of a surface scattering antenna is depicted in fig. 1. The surface scattering antenna 100 comprises a plurality of scattering elements 102a, 102b distributed along a wave propagating structure 104. The wave propagating structure 104 may be a microstrip, a coplanar waveguide, a parallel plate waveguide, a dielectric slab, a closed or tubular waveguide, or any other structure capable of supporting the propagation of guided waves or surface waves 105 along or within the structure. The wavy line 105 is a symbolic depiction of the guided wave or surface wave, and the symbolic depiction is not intended to represent the actual wavelength or amplitude of the guided wave or surface wave; also, while the wavy line 105 is depicted as being located within the wave-propagating structure 104 (e.g., for guided waves in a metal waveguide), for surface waves, the wave may be located substantially outside of the wave-propagating structure (e.g., for TM modes on a single-wire transmission line or "spurious plasmons" on an artificial impedance surface). The scattering elements 102a, 102b may comprise metamaterial elements that may be embedded within the wave-propagating structure 104, located on a surface of the wave-propagating structure 104, or located within the evanescent vicinity of the wave-propagating structure 104; for example, the scattering elements can comprise complementary metamaterial elements, such as those set forth in U.S. patent application publication No. 2010/0156573 entitled "materials for surfaces and waveguides," to d.r. smith et al, which is incorporated herein by reference.

The surface scattering antenna further comprises at least one feed connector 106, the at least one feed connector 106 being configured to couple the wave propagating structure 104 with a feed structure 108. The feed structure 108 (schematically depicted as a coaxial cable) may be a transmission line, a waveguide, or any other structure capable of providing an electromagnetic signal that may be launched into a guided wave or surface wave 105 of the wave propagating structure 104 via the feed connector 106. The feed connector 106 may be, for example, a coaxial to microstrip connector (e.g., an SMA to PCB adapter), a coaxial to waveguide connector, a mode matching transition, or the like. Although fig. 1 depicts a feed connector configured for "end launch," whereby the guided wave or surface wave 105 may be launched from a peripheral region of the wave propagating structure (e.g., from an end of a microstrip or from an edge of a parallel plate waveguide), in other embodiments, the feed structure may be attached to a non-peripheral portion of the wave propagating structure, whereby the guided wave or surface wave 105 may be launched from the non-peripheral portion of the wave propagating structure (e.g., from a midpoint of a microstrip or through a hole drilled in a top or bottom plate of a parallel plate waveguide); and other embodiments may provide multiple feed connectors attached to the wave-propagating structure at multiple locations (peripheral and/or non-peripheral).

The scattering elements 102a, 102b 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 the previously cited d.r.smith et al patents, and are further described in this disclosure. The adjustable scattering element may comprise an element that is adjustable in response to a voltage input (e.g., a bias voltage for an active element (such as a varactor, a transistor, a diode) or for an element incorporating a tunable dielectric material (such as a ferroelectric)), a current input (e.g., direct injection of charge carriers into the active element), a light input (e.g., illumination of a photosensitive material), a field input (e.g., a magnetic field for an element comprising a nonlinear magnetic material), a mechanical input (e.g., MEMS, an actuator, a hydraulic system), etc. In the schematic example of fig. 1, a scattering element that has been adjusted to a first state having first electromagnetic properties is depicted as first element 102a, while a scattering element that has been adjusted to a second state having second electromagnetic properties is depicted as second element 102 b. Depiction of scattering elements having first and second states corresponding to first and second electromagnetic properties is not intended to be limiting: embodiments may provide a scattering element that is discretely adjustable to be selected from a plurality of discrete states corresponding to a plurality of different discrete electromagnetic properties or that is continuously adjustable to be selected from a continuum of states corresponding to different continuous electromagnetic properties. Moreover, the particular adjustment pattern depicted in fig. 1 (i.e., the alternating arrangement of elements 102a and 102 b) is merely an exemplary configuration and is not intended to be limiting.

In the example of fig. 1, the scattering elements 102a, 102b have first and second coupling coefficients (coupling) for the guided wave or surface wave 105 as a function of the first and second electromagnetic properties, respectively. For example, the first and second coupling coefficients may be first and second degrees of polarization of the scattering element at a frequency or frequency band of the guided wave or surface wave. In one approach, the first coupling coefficient is a substantially non-zero coupling coefficient and the second coupling coefficient is a substantially zero coupling coefficient. In another approach, the two coupling coefficients are substantially non-zero, but the first coupling coefficient is substantially greater (or less) than the second coupling coefficient. Due to the first and second coupling coefficients, the first and second scattering elements 102a, 102b may generate a plurality of scattered electromagnetic waves having amplitudes that are a function (e.g., proportional) of the respective first and second coupling coefficients in response to the guided wave or surface wave 105. The superposition of the scattered electromagnetic waves includes the electromagnetic waves described in this example as plane waves 110 radiated from the surface scattering antenna 100.

The occurrence of a plane wave can be understood by considering a particular tuning pattern of scattering elements (e.g., an alternating arrangement of first and second scattering elements in fig. 1) as defining a pattern of a grating that scatters the guided or surface wave 105 to generate the plane wave 110. Because the pattern is adjustable, some embodiments of surface scattering antennas may provide adjustable gratings or more generally holograms, where the adjustment pattern of the scattering element may be selected according to holographic principles. It is assumed that, for example, a guided wave or surface wave can be formed from a complex scalar input wave ψ as a function of position along the wave propagation structure 104_inIs shown and it is desirable that the surface scattering antenna generation can be made by another complex scalar wave psi_outThe output wave is shown. Then, an adjustment pattern of the scattering elements corresponding to an interference pattern of the input and output waves along the wave propagation structure may be selected. For example, the scattering element may be tuned to provide a guided or surface wave as a wave consisting of Re [ psi ]_outψ_in ^*]The coupling coefficient of a function of (e.g., proportional to, or a step function of) a given interference term. In this way, embodiments of surface scattering antennas may be tuned to pass identificationOutput wave psi corresponding to the selected beam pattern_outAnd then adjust the scattering elements accordingly as described above to provide an arbitrary antenna radiation pattern. Embodiments of the surface scattering antenna may thus be adjusted to provide, for example, a selected beam direction (e.g., beam steering), a selected beam width or shape (e.g., fan or pencil beams with wide or narrow beam widths), a selected null arrangement (e.g., null steering), a selected multi-beam arrangement, a selected polarization state (e.g., linear, circular, or elliptical polarization), a selected overall phase, or any combination thereof. Alternatively or additionally, embodiments of the surface scattering antenna may be tuned to pass a selected near-field radiation profile, for example, to provide near-field focusing and/or near-field nulling.

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 wave-propagating structure with inter-element spacing much smaller than (e.g., less than one-fourth or one-fifth of) the free-space wavelength corresponding to the operating frequency of the device. In some approaches, the operating frequency is a microwave frequency selected from frequency bands such as Ka, Ku, and Q corresponding to centimeter-sized free-space wavelengths. This length scale allows the fabrication of the scattering element using conventional printed circuit board technology as described below.

In some approaches, the surface scattering antenna includes a substantially one-dimensional wave-propagating structure 104 having a substantially one-dimensional scattering element arrangement, and the tuning pattern of the one-dimensional arrangement may provide a selected antenna radiation distribution, for example, as a function of zenith angle (i.e., with respect to a zenith direction parallel to the one-dimensional wave-propagating structure). In other approaches, the surface scattering antenna includes a substantially two-dimensional wave-propagating structure 104 having a substantially two-dimensional arrangement of scattering elements, and the adjustment pattern of the two-dimensional arrangement may provide a selected antenna radiation distribution as a function of, for example, zenith and azimuth angles (i.e., with respect to a zenith direction perpendicular to the two-dimensional wave-propagating structure). Exemplary tuning patterns and beam patterns for a surface scattering antenna comprising a two-dimensional array of scattering elements distributed over a planar, rectangular wave-propagating structure are shown in fig. 2A-4B. In these exemplary embodiments, a planar rectangular wave propagating structure includes a monopole antenna feed located at the geometric center of the structure. Fig. 2A shows an adjustment pattern corresponding to a narrow beam having a selected zenith and azimuth as shown in the beam pattern diagram of fig. 2B. Fig. 3A shows an adjustment pattern corresponding to a dual beam far field distribution as shown in the beam pattern diagram of fig. 3B. Fig. 4A represents an adjustment pattern that provides near field focusing as shown by the field intensity map of fig. 4B (which shows the field intensity along a plane perpendicular to and bisecting the long dimension of the rectangular wave propagating structure).

In some approaches, the wave-propagating structure is a modular wave-propagating structure, and a plurality of modular wave-propagating structures may be assembled to constitute a modular surface-scattering antenna. For example, a plurality of generally one-dimensional wave-propagating structures may be arranged, e.g., in an interdigitated pattern, to generate an effective two-dimensional arrangement of scattering elements. The interdigitated arrangement may include, for example, a series of adjacent linear structures (i.e., sets of parallel straight lines) or a set of adjacent curvilinear structures (i.e., sets of continuous offset curves, such as sinusoids) that substantially fill the two-dimensional surface area. As another example, a plurality of generally two-dimensional wave-propagating structures (each of which may itself comprise a series of one-dimensional structures, as described above) may be assembled to create a larger aperture with a larger number of scattering elements; and/or a plurality of generally two-dimensional wave-propagating structures may be assembled into a three-dimensional structure (e.g., forming an a-frame structure, a pyramid structure, or other multi-faceted structure). In these modular assemblies, each of the plurality of modular wave propagating structures may have its own feed connector 106, and/or the modular wave propagating structures may be configured to couple a guided wave or surface wave of a first modular wave propagating structure into a guided wave or surface wave of a second modular wave propagating structure through a connection between the two structures.

In some applications of the modular approach, the number of modules to be assembled may be selected to achieve an aperture size that provides a desired telecommunications data capacity and/or quality of service, and/or the three-dimensional arrangement of the modules may be selected to reduce possible scan losses. Thus, for example, a modular assembly may include a plurality of modules (the modules need not be contiguous) mounted at various locations/orientations flush with a surface of a vehicle, such as an aircraft, spacecraft, ship, ground vehicle, or the like. In these and other approaches, the wave-propagating structure may have a generally non-linear or generally non-planar shape, thereby conforming to a particular geometry, thereby providing a conformal surface-scattering antenna (e.g., conforming to a curved surface of a vehicle).

More generally, surface scattering antennas are reconfigurable antennas that can be reconfigured by selecting an adjustment pattern of scattering elements to cause corresponding scattering of a guided wave or surface wave to generate a desired output wave. Assume, for example, that a surface scattering antenna includes locations r distributed along a wave-propagating structure 104 (or along multiple wave-propagating structures for a modular embodiment) as in fig. 1_jAnd has a corresponding plurality of adjustable coupling coefficients { α } for the guided wave or surface wave 105_jA plurality of scattering elements of. Guided wave or surface wave 105 presents a wave amplitude a to the jth scattering element while propagating along or within the wave propagating structure(s)_jAnd phaseSubsequently, an output wave is generated as a superposition of the waves scattered from the plurality of scattering elements:

where E (θ, φ) represents the electric field component of the output wave over the far field radiation range, R_j(θ, φ) represents the response of the jth scattering element to the coupling coefficient α_jThe resulting excitation produces a (normalized) electric field pattern of scattered waves, and k (θ, φ) represents a wave vector of magnitude ω/c at (θ, φ) perpendicular to the radiation range embodiments of the surface scattering antenna may therefore provide for adjustment to adjust a plurality of coupling coefficients { α { by adjusting a plurality of coupling coefficients according to equation (1) }_jIs generated as desiredA reconfigurable antenna outputting a wave E (theta, phi).

Amplitude A of guided or surface waves_jAnd phaseAs a function of the propagation characteristics of the wave propagating structure 104. These propagation characteristics may include, for example, an effective refractive index and/or an effective wave impedance, and these effective electromagnetic characteristics may be determined, at least in part, by the placement and adjustment of scattering elements along the wave-propagating structure. In other words, the wave propagation structure in combination with the adjustable scattering element may provide an adjustable effective medium for propagation of guided or surface waves, for example as described in the previously cited d.r. smith et al patents. Thus, the amplitude A of the wave despite the guided or surface wave_jAnd phaseMay depend on the adjustable scattering element coupling coefficient α_j} (i.e., A_j＝A_j({α_j})，({α_j}), in some embodiments these dependencies may be predicted substantially from the effective medium description of the wave propagation structure.

In some approaches, the reconfigurable antenna is adjustable to provide a desired polarization state of the output wave E (θ, φ). Suppose for example that the first and second subsets LP of scattering elements⁽¹⁾And LP⁽²⁾Providing respective substantially linearly polarized and substantially perpendicular (normalized) electric field patterns R⁽¹⁾(theta, phi) and R⁽²⁾(θ, φ) (e.g., the first and second objects may be scattering elements oriented perpendicularly on the surface of the wave propagating structure 104). The antenna output wave E (θ, φ) may then be expressed as the sum of two linearly polarized components:

E(θ,φ)＝E⁽¹⁾(θ,φ)+E⁽²⁾(θ,φ)＝Λ⁽¹⁾R⁽¹⁾(θ,φ)+Λ⁽²⁾R⁽²⁾(θ,φ) (2)

wherein the content of the first and second substances,

is the complex magnitude of the two linearly polarized components, therefore, the polarization E (θ, φ) of the output wave may be adjusted by adjusting a plurality of coupling coefficients { α) according to equations (2) - (3)_jFor example to provide an output wave of any desired polarization (e.g. linear, circular or elliptical).

Alternatively or additionally, for embodiments in which the wave-propagating structure has multiple feeds (e.g., one feed for each "finger" of an interdigitated arrangement of one-dimensional wave-propagating structures, as described above), the desired output wave E (θ, φ) may be controlled by adjusting the gain of the individual amplifiers for the multiple feeds. Adjusting the gain for a particular feeder will correspond to having A_j' s is multiplied by the gain factor G of those elements j fed by a particular feeder. In particular, a first wave propagating structure with a first feed (or a first set of such structures/feeds) is selected from LP⁽¹⁾And a second wave-propagating structure having a second feed (or a second set of such structures/feeds) coupled to the element selected from LP⁽²⁾The method of coupling elements of (a), may compensate for depolarization losses (e.g., when deviating from a broadside scanning beam) by adjusting the relative gain between the first feed and the second feed.

As previously mentioned in the context of fig. 1, in some approaches, the surface scattering antenna 100 includes a wave-propagating structure 104 that may be implemented as a microstrip or a parallel plate waveguide (or multiple such elements); and in these approaches, the scattering elements may comprise complementary metamaterial elements such as those set forth in the previously referenced d.r. smith et al patents. Turning now to fig. 5, an exemplary unit cell 500 of a microstrip or parallel plate waveguide is shown, which includes a lower conductor or ground plane 502 (made of copper or similar material), a dielectric substrate 504 (made of Duriod, FR4, or similar material), and an upper conductor 506 (made of copper or similar material) embedded with a complementary metamaterial element 510, in this case, the complementary metamaterial element 510 is a complementary electrical lc (celc) metamaterial element defined by shaped apertures 512 that have been etched or patterned (e.g., by PCB processing) in the upper conductor.

A CELC element such as that shown in fig. 5 is substantially responsive to a plane parallel to the CELC element and perpendicular to the CELC gap (i.e., in the orientation for fig. 5)Direction) Applied by the supplement (see t.h. hand et al, "characteristics of compensated electric field coupled magnetic sources surfaces," Applied Physics Letters 93,212504(2008), incorporated herein by reference). Thus, a magnetic field component of a guided wave (as exemplified by guided wave or surface wave 106 of FIG. 1) propagating along a microstrip or parallel plate waveguide may induce a magnetic excitation of element 510 that is substantially characterized alongThe directionally oriented magnetic dipoles excite, thereby generating a scattered electromagnetic wave that is essentially a magnetic dipole radiation field.

It should be noted that the shaped aperture 512 also defines a conductor island 514 that is electrically separated from the upper conductor 506, and in some approaches the scattering element can be made adjustable by disposing an adjustable material within the shaped aperture 512 and/or proximate to the shaped aperture 512 and then applying a bias between the conductor island 514 and the upper conductor 506. For example, as shown in FIG. 5, the unit cells may be immersed in a layer of liquid crystal material 520. Liquid crystals have a dielectric constant that is a function of the orientation of the molecules that make up the liquid crystal; and the orientation can be controlled by applying a bias (equivalent to a bias electric field) across the liquid crystal; thus, the liquid crystal can provide a voltage tunable dielectric constant for electromagnetic characteristic adjustment of the scattering element.

For example, by providing a liquid crystal containment structure on the upper surface of the wave-propagating structure, the liquid crystal material 520 may be held in close proximity to the scattering element. An exemplary configuration of a liquid crystal containment structure is shown in fig. 5, which illustrates a liquid crystal containment structure including a cover 532 and optionally one or more supports or spacers 534, the one or more supports or spacers 534 providing separation between the upper conductor 506 and the cover 532. In some approaches, the liquid crystal containment structure is a machined or injection molded plastic part having a planar surface engageable with an upper surface of the wave propagating structure, the planar surface including one or more recesses (e.g., grooves or recesses) that can overlie the scattering element; and these recesses may be filled with liquid crystal by, for example, a vacuum injection process. In other methods, the support 534 is a spherical spacer (e.g., spherical resin particles); or walls or pillars formed by a photolithographic process (e.g., as described in Sato et al, U.S. Pat. No. 4,874,461, "Method for manufacturing liquid crystal device with space for by photolithography", which is incorporated herein by reference); cover 532 is then affixed to support 534, followed by mounting of the liquid crystal (e.g., by vacuum injection).

For nematic liquid crystals in which the molecular orientation is characterized by a director field, the material provides a large dielectric constant for the electric field component parallel to the directorAnd the material can provide a smaller dielectric constant for the electric field component perpendicular to the director_⊥. The application of a bias voltage introduces bias field lines across the shaped aperture and the director tends to align parallel to these field lines (the degree of alignment increases with the bias voltage). Because these biased electric field lines are substantially parallel to the electric field lines generated during scattering excitation of the scattering element, the permittivity exhibited by the biased scattering element correspondingly tends to(i.e., with increasing bias). On the other hand, the dielectric constant exhibited by an unbiased scattering element may depend on the unbiased configuration of the liquid crystal. When unbiased liquid crystal is out of order to the greatest extent(i.e., having randomly oriented microdomains), the unbiased scattering element may exhibit an average dielectric constantThe unbiased scattering element may appear as if the unbiased liquid crystal is maximally aligned perpendicular to the biased electric field lines (i.e., before the biased electric field is applied)_⊥Such a small dielectric constant. Thus, for embodiments in which it is desirable to achieve a larger tuning range of the permittivity exhibited by the scattering element (corresponding to a larger tuning range of the effective capacitance of the scattering element and hence of the resonant frequency of the scattering element), the unit cell 500 may comprise a position-dependent alignment layer disposed on the top and/or bottom surface of the liquid crystal layer 510, and the position-dependent alignment layer is configured to align the liquid crystal director in a direction substantially perpendicular to the bias electric field lines corresponding to the applied bias voltage. The alignment layer may comprise, for example, a polyimide layer that is rubbed or otherwise patterned (e.g., by machining or photolithography) to introduce microscopic grooves that extend parallel to the channels of the shaped apertures 512.

Alternatively or additionally, the unit cell may provide a first bias that aligns liquid crystal substantially perpendicular to the channels of the shaped aperture 512 (e.g., by introducing a bias between the upper conductor 506 and the conductor island 514, as described above), and a second bias that aligns liquid crystal substantially parallel to the channels of the shaped aperture 512 (e.g., by introducing electrodes located above the upper conductor 506 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 achieved by, for example, alternating between the first and second bias voltages or adjusting the relative strengths of the first and second bias voltages.

In some approaches, the sacrificial layer may enhance the effect of liquid crystal tuning by allowing a greater amount of liquid crystal within the vicinity of the shaped aperture 512. An illustration of this approach is shown in fig. 6, which shows the unit cell 500 of fig. 5 in a profile view, with the addition of a sacrificial layer 600 (e.g., a polyimide layer) deposited between a dielectric substrate 504 and an upper conductor 506. After etching of the upper conductor 506 to define the shaped aperture 512, further selective etching of the sacrificial layer 600 generates a cavity 602, which cavity 602 may then be filled with liquid crystal 520. In some approaches, another masking layer is used to define the pattern for selective etching of sacrificial layer 600 (not implemented by upper conductor 506 or implemented in conjunction with upper conductor 506).

Exemplary liquid crystals that may be deployed in various embodiments include 4-cyano-4' -pentylbiphenyl, high birefringence eutectic LC mixtures such as LCMS-107(LC mate) or GT3-23001 (Merck). Some methods may use dual frequency liquid crystals. In a dual-frequency liquid crystal, the director is aligned approximately parallel to the applied low frequency bias field, but approximately perpendicular to the applied high frequency bias field. Thus, for methods of deploying these dual-frequency liquid crystals, tuning of the scattering element can be achieved by adjusting the frequency of the applied bias signal. Other approaches may deploy Polymer Network Liquid Crystals (PNLC) or Polymer Dispersed Liquid Crystals (PDLC), which typically provide much shorter relaxation/switching times for the liquid crystal. Examples of the former are thermally or UV cured mixtures of polymers (such as BPA-dimethacrylate) in nematic LC matrices (such as LCMS-107); see, Y.H.Fan et al, "Fast-responding and scattering-free polymeric networks for not having light modulators," Applied Physics letters 84,1233-35(2004), incorporated herein by reference. Examples of Polymer Dispersed Liquid Crystals (PDLCs) are porous polymer materials (such as PTFE films) impregnated with nematic LCs (such as LCMS-107); see "Microwave variable delay time using a membrane estimated with a liquid crystal", Microwave symposium Digest,2002IEEE MTT-S International, volume 1, pp 363-.

Turning now to the method of providing a bias voltage between conductor island 514 and upper conductor 506, it is first noted that upper conductor 506 extends adjacent one unit cell to the next, and that electrical connection to the upper conductor of each unit cell can be achieved by a single connection to the upper conductor of a microstrip or parallel plate waveguide of which unit cell 500 is a constituent. With respect to the conductor islands 514, FIG. 5 shows an example of how the bias lines 530 may be attached to the conductor islands. In this example, the bias line 530 is attached at the center of the conductor island and extends away from the conductor island along the plane of symmetry of the scattering element; by this positioning along the plane of symmetry, the electric field experienced by the bias line during scattering excitation of the scattering element is substantially perpendicular to the bias line and thus does not excite a current in the bias line, which may destroy or alter the scattering properties of the scattering element. The bias line 530 may be mounted in a unit cell, for example, by depositing in an insulating layer (e.g., polyimide), etching the insulating layer at the center of the conductor island 514, and then patterning a conductive film (e.g., a Cr/Au bilayer) defining the bias line 530 using a take-off process.

Fig. 7A-7H illustrate various CELC elements that may be used in accordance with various embodiments of surface scattering antennas. These are schematic illustrations of exemplary elements, are not drawn to scale, and are intended to represent only the various types of possible CELC elements suitable for use in various embodiments. Fig. 7A corresponds to the elements used in fig. 5. FIG. 7B shows an alternative CELC element equivalent to the topology of FIG. 7A, but which uses a wavy perimeter to increase the length of the arms of the element, thereby increasing the capacitance of the element. Fig. 7C and 7D illustrate a pair of element types that may be used to provide polarization control. When these orthogonal elements have edgesWhen excited by a guided or surface wave of a directionally oriented magnetic field, the applied magnetic field generates a magnetic excitation which is essentially characterized by a magnetic dipole excitation, relative to fig. 7C or 7D, respectivelyThe direction is +45 degrees or-45 degrees. Fig. 7E and 7F show a variant of such orthogonal type CELC elements, where the arms of the CELC element are also tilted at an angle of ± 45 °. These tilted designs may provide a purer magnetic dipole response due to the C that produces the magnetic dipole responseAll regions of the ELC element are oriented orthogonally to the excitation field (and thus not excited) or at a 45 ° angle with respect to the field. Finally, FIGS. 7E and 7F illustrate similarly angled variations of the corrugated CELC element of FIG. 7B.

Although fig. 5 shows an example of a metamaterial element 510 patterned on the upper conductor 506 of a wave-propagating structure such as a microstrip, in another approach, as shown in fig. 8, the metamaterial element is not positioned on the microstrip itself; rather, the metamaterial elements are positioned within the evanescent proximity of the microstrips (i.e., within the fringe field of the microstrips). Thus, fig. 8 shows a microstrip configuration having a ground plane 802, a dielectric substrate 804 and an upper conductor 806, with a conductive strip 808 located along either side of the microstrip. These conductive strips 808 embed complementary metamaterial elements 810 defined by shaped apertures 812. In this example, the complementary metamaterial elements are CELC elements such as the corrugated perimeter shown in fig. 7B. As shown in fig. 8, vias 840 can be used to connect the bias line 830 with the conductive islands 814 of each meta-material element. As a result, the construction can be easily implemented using a two-layer PCB process (two conductive layers with an intermediate dielectric layer), layer 1 providing the microstrip signal traces and metamaterial elements, and layer 2 providing the microstrip ground plane and bias traces. The dielectric and conductive layers may be a high efficiency material such as copper clad Rogers 5880. As previously described, tuning may be achieved by disposing a liquid crystal layer (not shown) over the metamaterial elements 810.

In another approach, as in fig. 9A and 9B, the wave-propagating structure is a coplanar waveguide (CPW) and the metamaterial elements are located within the evanescent proximity of the coplanar waveguide (i.e., within the fringing field of the coplanar waveguide). Thus, fig. 9A and 9B show a coplanar waveguide configuration having a lower ground plane 902, a central ground plane 906 on either side of a CPW signal trace 907, and an upper ground plane 910 embedding complementary meta-material elements 920 (only one shown, but the method locates a series of such elements along the length of the CPW). These continuous conductive layers are separated by dielectric layers 904, 908. The coplanar waveguide can be bounded by columns (colonnades) of vias 930 that can be used to cut higher order modes of the CPW and/or reduce crosstalk with neighboring CPWs (not shown). The CPW bandwidth 909 can be varied along the length of the CPW to control coupling with the metamaterial element 920, e.g., aperture tapering for enhancing aperture efficiency and/or controlling beam distribution. The CPW gap width 911 can be adjusted to control the line impedance. As shown in fig. 9B, a third dielectric layer 912 and vias 940 can be used to connect the bias line 950 with the conductive island 922 of each meta-material element and with the bias pad 952 on the bottom side of the structure. The channels 924 in the third dielectric layer 912 allow liquid crystal (not shown) to be disposed within the vicinity of the shaped apertures of the conductive elements. This configuration can be achieved using a four layer PCB process (four conductive layers with three intermediate dielectric layers). These PCBs may be fabricated using a lamination stage along with formation by blind buried vias and electroplating and electroless deposition techniques.

In another approach, shown in fig. 10 and 11, the wave-propagating structure is a closed or tubular waveguide, and the metamaterial elements are positioned along the surface of the closed waveguide. Thus, fig. 10 shows a closed or tubular waveguide having a rectangular cross-section defined by a moat 1002 and a conducting surface 1004 embedded in a metamaterial element 1010. As shown in the cross-sectional view, vias 1020 through the dielectric layer 1022 can be used to connect the bias line 1030 with the conductive islands 1012 of the metamaterial elements. The slot 1002 can be implemented as a milled or cast piece of metal to provide a "floor and wall" of a closed waveguide, and the waveguide "ceiling" can be implemented as a two-layer printed circuit board, with the top layer providing the bias track 1030 and the bottom layer providing the meta-material element 1010. The waveguide can be loaded with a dielectric layer 1040 (such as PTFE) having a smaller trench 1050, the smaller trench 1050 being able to be filled with liquid crystal to allow tuning of the metamaterial element.

In an alternative closed waveguide embodiment, as shown in FIG. 11, a closed waveguide having a rectangular cross-section is defined by a trench 1102 and a conducting surface 1104. As shown in the cross-sectional view of the unit cell, the conductive surface 1104 has an iris 1106 that allows coupling between the guided waves and the resonant element 1110. In this example, the complementary metamaterial elements are corrugated perimeter CELC elements, such as the corrugated perimeter CELC elements shown in fig. 7B. Although rectangular coupling irises are shown, other shapes can be used, and the size of the irises can be varied along the length of the waveguide to control coupling with the scattering element (e.g., aperture tapering to enhance aperture efficiency and/or control beam distribution). A pair of vias 1120 through the dielectric layer 1122 can be used with short routing lines 1125 to connect the bias line 1130 with the conductive islands 1112 of meta-material elements. The slot 1102 can be implemented as a milled or cast piece of metal to provide a "floor and wall" of a closed waveguide, and the waveguide "ceiling" can be implemented as a two-layer printed circuit board, with the top layer providing the meta-material element 1110 (and offset traces 1130) and the bottom layer providing the iris 1106 (and offset routing 1125). The meta-material element 1110 may optionally be bounded by columns of vias 1150 extending through the dielectric layer 1122 to reduce coupling or cross-talk between adjacent unit cells. As before, tuning may be achieved by disposing a liquid crystal layer (not shown) over the metamaterial element 1110.

Although the waveguide embodiments of fig. 10 and 11 provide a waveguide having a simple rectangular cross-section, in some approaches the waveguide may include one or more ridges (e.g., a double-ridge waveguide). The ridge waveguide can provide a larger bandwidth than a simple rectangular waveguide, and the geometry (width/length) of the ridge can be varied along the length of the waveguide to control coupling with the scattering element (e.g., aperture tapering to enhance aperture efficiency and/or control beam distribution) and/or to provide a smooth impedance transition (e.g., from an SMA connector feed).

In various approaches, the bias lines may be addressed directly, e.g. by extending the bias line for each scattering element to a pad structure for connection to antenna control circuitry, or matrix addressed, e.g. by providing each scattering element with a bias circuit that can be addressed by rows and columns. Fig. 12 shows an example of a configuration that provides direct addressing for the arrangement of scattering elements 1200 on the surface of a microstrip 1202, where a plurality of bias lines 1204 extend along the length of the microstrip to deliver respective biases to the scattering elements (alternatively, the bias lines 1204 may extend perpendicular to the microstrip and along the length of the microstrip to the pads or viasA hole). (the figure also shows an example of how scattering elements may be arranged with a vertical orientation, e.g. to provide polarisation control; in this arrangement guided waves propagating along a microstrip have a general direction alongThe directionally oriented magnetic field and thus the two orientations of the scattering element can be coupled, which results in a magnetic field that can be substantially opposite toMagnetic dipole excitations oriented at ± 45 °). Fig. 13 shows an example of a configuration that provides matrix addressing for the arrangement of scattering elements 1300 (e.g., on the surface of a parallel plate waveguide). Where each scattering element is connected via a bias line 1302 to a bias circuit 1304 that can be addressed by a bank input 1306 and a column input 1308 (note that each bank input and/or column input may comprise one or more signals, e.g., each bank or column may be addressed by a single line or set of parallel lines dedicated to that bank or column). Each bias circuit may include, for example, a switching device (e.g., a transistor), a memory device (e.g., a capacitor), and/or additional circuitry such as logic/multiplexing circuitry, analog-to-digital conversion circuitry, and the like. The circuitry may be readily fabricated using monolithic integration, for example, using Thin Film Transistor (TFT) processes, or as hybrid components of integrated circuits mounted on a wave-propagating structure, for example, using Surface Mount Technology (SMT). In some approaches, the bias voltage may be adjusted by adjusting the amplitude of the AC bias signal. In other approaches, the bias voltage may be adjusted by applying pulse width modulation to the AC signal.

Referring now to FIG. 14, an exemplary embodiment is depicted as a system block diagram. System 1400 includes a communication unit 1410 coupled to an antenna element 1420 by one or more feeds 1412. Communication unit 1410 may include, for example, a mobile broadband satellite transceiver or transmitter, a receiver, or a transceiver module for a radio or microwave communication system, and may incorporate data multiplexing/demultiplexing circuitry, encoder/decoder circuitry, regulator/demodulator circuitry, frequency up/down converters, filters, amplifiers, duplexers, and so forth. The antenna unit comprises at least one surface scattering antenna, which may be configured to transmit, receive, or both; and in some approaches, the antenna element 1420 may include multiple surface scattering antennas, e.g., first and second surface scattering antennas configured to transmit and receive, respectively. For embodiments having surface scattering antennas with multiple feeds, the communication unit may include MIMO circuitry. The system 1400 further comprises an antenna controller 1430, the antenna controller 1430 being configured to provide a control input 1432 for determining the configuration of the antenna. For example, the control inputs may include an input for each scattering element (e.g., for a direct addressing configuration such as shown in fig. 12), row and column inputs (e.g., for a matrix addressing configuration such as shown in fig. 13), adjustable gain for an antenna feed, and so forth.

In some approaches, the antenna controller 1430 includes circuitry configured to provide a control input 1432 corresponding to a selected or desired antenna radiation pattern. For example, antenna controller 1430 may store sets of configurations of surface scattering antennas, e.g., as a look-up table mapping sets of desired antenna radiation patterns (corresponding to various beam directions, beam widths, polarization states, etc., as previously discussed in this disclosure) with corresponding sets of values for control inputs 1432. The look-up table is calculated in advance, for example, by performing a full-wave simulation of the antenna for a range of values of the control input or by placing the antenna in a test environment and measuring the antenna radiation pattern corresponding to the range of values of the control input. In some methods, the antenna controller may be configured to utilize the look-up table to calculate a control input from a regression analysis; for example by interpolating control inputs between two antenna radiation patterns stored in a look-up table (e.g. allowing continuous beam steering when the look-up table only comprises discrete increments of beam steering angle). Antenna controller 1430 may optionally be configured, for example, by calculating interference term Re [ psi ]_outψ_in ^*]Corresponding holographic pattern(as previously discussed in this disclosure), or by calculating a coupling coefficient { α } that provides a selected or desired radiation pattern according to equation (1) provided previously in this disclosure_jCorresponding to the value of the control input, to dynamically calculate a control input 1432 corresponding to the selected or desired antenna radiation pattern.

In some approaches, the antenna element 1420 optionally includes a sensor element 1422, the sensor element 1422 having sensor components that detect environmental conditions of the antenna (such as its position, orientation, temperature, mechanical deformation, etc.). The sensor components may include one or more GPS devices, gyroscopes, thermometers, strain gauges, etc., and the sensor unit may be coupled with the antenna controller to provide sensor data 1424 such that the control input 1432 may be adjusted to compensate for translation or rotation of the antenna (e.g., if the antenna is mounted on a moving platform such as an airplane) or to compensate for temperature drift, mechanical deformation, etc.

In some approaches, the communication unit may provide a feedback signal 1434 to the antenna controller for controlling feedback adjustment of the input. For example, the communication unit may provide a bit error rate signal, and the antenna controller may include feedback circuitry (e.g., DSP circuitry) that adjusts the antenna configuration to reduce channel noise. Alternatively or additionally, for pointing or steering applications, the communication unit may provide a beacon signal (e.g., from a satellite beacon) and the antenna controller may include feedback circuitry (e.g., pointing lock DSP circuitry for a mobile broadband satellite transceiver).

An exemplary embodiment is shown in the process flow diagram in fig. 15. The flow 1500 includes an operation 1510 of selecting a first antenna radiation pattern for a surface scattering antenna that is adjustable in response to one or more control inputs. For example, an antenna radiation pattern may be selected that directs a main beam of the radiation pattern at a location of a telecommunication satellite, a telecommunication base station, or a telecommunication mobile platform. Alternatively or additionally, the antenna radiation pattern may be selected to place nulls of the radiation pattern at desired locations, for example, for secure communications or to remove noise sources. Alternatively or additionally, the antenna radiation pattern may be selected to provide a desired polarization state, such as circular polarization (e.g., for Ka band satellite communications) or linear polarization (e.g., for Ku band satellite communications). The flow 1500 includes an operation 1520 of determining a first value of one or more control inputs corresponding to the selected first antenna radiation pattern. For example, in the system of fig. 14, the antenna controller 1430 may include circuitry configured to determine the value of the control input by utilizing a look-up or by calculating a hologram corresponding to the desired antenna radiation pattern. Flow 1500 optionally includes an operation 1530 of providing a first value for one or more control inputs for the surface scattering antenna. For example, antenna controller 1430 can apply bias voltages to various scattering elements, and/or antenna controller 1430 can adjust the gain of an antenna feed. Flow 1500 optionally includes an operation 1540 of selecting a second antenna radiation pattern different from the first antenna radiation pattern. Also, this may include selecting, for example, a second beam direction or a second null placement. In one application of the method, the satellite communications terminal can switch between multiple satellites, for example, to optimize capacity during peak loads, to switch to another satellite that may have been put into service, or to switch from a primary satellite that has failed or is offline. Flow 1500 optionally includes an operation 1550 of determining a second value of one or more control inputs corresponding to the selected second antenna radiation pattern. Also, this may include, for example, using a look-up table or computing a holographic pattern. Flow 1500 optionally includes an operation 1560 of providing a second value for one or more control inputs of the surface scattering antenna. Also, this may include, for example, applying a bias and/or adjusting the feed gain.

Another exemplary embodiment of a process flow diagram is depicted in fig. 16. Flow 1600 includes an operation 1610 of identifying a first target for a first surface scattering antenna having a first adjustable radiation pattern responsive to one or more first control inputs. The first target may be, for example, a telecommunications satellite, a telecommunications base station, or a telecommunications mobile platform. The flow 1600 includes an operation 1620 of repeatedly adjusting one or more first control inputs to provide a substantially continuous change in the first adjustable radiation pattern in response to a first relative motion between the first target and the first surface scattering antenna. For example, in the system of fig. 14, the antenna controller 143 may include circuitry configured to steer the radiation pattern of the surface scattering antenna, e.g., to track the motion of a non-geostationary satellite, to maintain a directional lock from a moving platform (such as an aircraft or other vehicle) through a geostationary satellite, or to maintain a directional lock when both the target and the antenna are moving. Flow 1600 optionally includes an operation 1630 of identifying a second target for a second surface scattering antenna having a second adjustable radiation pattern responsive to one or more second control inputs; and flow 1600 optionally includes an operation 1640 of repeatedly adjusting one or more second control inputs to provide a substantially continuous change in the second adjustable radiation pattern in response to relative motion between the second target and the second surface-scattering antenna. For example, some applications may deploy a primary antenna unit that tracks a first object (such as a first non-geostationary satellite) and a second or auxiliary antenna unit that tracks a second object (such as a second non-geostationary satellite). In some approaches, the auxiliary antenna unit may include a smaller aperture antenna (tx and/or rx) used primarily to track the location of the second object (and optionally ensure linking with the second object with reduced quality of service (QoS)). Flow 1600 optionally includes an operation 1650 of adjusting one or more first control inputs to position a second target substantially within the main beam of the first adjustable radiation pattern. For example, in applications where the first and second antennas are part of a satellite communications terminal interacting with the star field of a non-geostationary satellite, the first or primary antenna may track a first member of the satellite star field until the first member approaches the horizon (or the first antenna suffers a measurable loss of scanning), at which time a "manual cut-off" is achieved by switching the first antenna to track a second member of the satellite star field that has been tracked by the second antenna or the auxiliary antenna. Flow 1600 optionally includes an operation 1660 of identifying a new target for a second surface scattering antenna different from the first and second targets; and the flow 1600 optionally includes an operation 1670 of adjusting one or more second control inputs to place the new target substantially within the main beam of the second adjustable radiation pattern. For example, after "manual cut-off," the second or auxiliary antenna can begin initiating a link with a third member of the satellite constellation (e.g., when it rises above level).

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. To the extent that 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, portions of the subject matter described herein may be implemented via an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), a Digital Signal Processor (DSP), or other integrated specification. However, those skilled in the art will recognize that some of the methods 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 signal bearing media include, but are not limited to, the following: recordable type media such as floppy disks, hard disk drives, Compact Disks (CDs), Digital Video Disks (DVDs), digital tape, 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, etc.).

In a general sense, those skilled in the art will recognize that the various aspects described herein, which can be implemented individually and/or collectively by various types of hardware, software, firmware, or any combination thereof, can be viewed as being comprised of various types of "circuitry". As a result, "circuitry" as used herein includes, but is not limited to, circuitry having at least one discrete circuit, circuitry having at least one integrated circuit, circuitry having at least one application specific integrated circuit, circuitry forming a general purpose computing device configured by a computer program (e.g., a general purpose computer configured by a computer program that at least partially implements a process and/or a device described herein, or a microprocessor configured by a computer program that at least partially implements a process and/or a device described herein), circuitry forming a memory device (e.g., in the form of random access memory), and/or circuitry forming a communication device (e.g., a modem, a communication switch, or an optoelectronic device). Those skilled in the art will recognize that the subject matter described herein may be implemented in an analog or digital manner, or some combination thereof.

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 they are not inconsistent herewith.

Those skilled in the art will recognize that the components (e.g., steps), devices, and objects described herein and the discussion related thereto are for conceptual clarity purposes only and that various configuration modifications are within the ability of those skilled in the art. As a result, as used herein, the specific examples and related discussion set forth are intended to be representative of the more general class thereof. In general, the use of any specific examples herein is also intended to be representative of its class, and the absence of such specific components (e.g., steps), devices, and objects herein should not be taken as indicative of the desired limitations.

With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art are able to translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. Various singular/plural permutations are not expressly set forth herein for purposes of clarity.

While particular aspects of the present subject matter described herein have been shown and described, it will be obvious 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. Furthermore, it is to be understood that the invention is defined by the appended claims. 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 inventions 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). Moreover, in those instances where the customary analogy to "at least one of A, B and C, etc." is used, in general such a construction is intended to convey the meaning that one of ordinary 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 the customary analogy to "A, B or at least one of C, etc." is used, such structure is intended to convey the meaning that one of 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 virtually any synonym and/or phrase representing two or more alternative items, whether in the specification, claims or drawings, should be understood as contemplating possibility of including one of the items, either of the items or both items. For example, the term "a or B" will be understood to include the possibility of "a" or "B" or "a and B".

For the appended claims, those skilled in the art will appreciate that the operations described herein may generally be performed in any order. Examples of such alternative orderings may include overlapping, interleaving, interrupting, reordering, incrementing, preparing, supplementing, simultaneously, reversing, or other varying orderings, unless the context dictates otherwise. Terms that are even analogous to "responsive," "about," or other past tense adjectives are generally not intended to exclude such variations, unless the 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.

Claims (101)

1. An antenna, comprising:

a waveguide; and

a plurality of scattering elements distributed along the waveguide with inter-element spacing substantially less than a free-space wavelength corresponding to an operating frequency of the antenna, wherein the plurality of scattering elements have a plurality of adjustable individual electromagnetic responses to guided wave modes of the waveguide, and the plurality of adjustable individual electromagnetic responses provide an adjustable radiation field of the antenna,

wherein the waveguide comprises one or more conductive surfaces that confine the guided wave mode inside the waveguide, and the plurality of scattering elements correspond to a plurality of apertures within the one or more conductive surfaces;

wherein the plurality of apertures define a respective plurality of conductive islands electrically separated from the one or more conductive surface layers, and the antenna further comprises:

a plurality of bias lines configured to provide respective biases between the one or more conductive surfaces and the respective plurality of conductive islands,

an electrically adjustable material disposed at least partially within respective proximity of the plurality of apertures, or an active element responsive to the bias voltage.

2. The antenna of claim 1, wherein the plurality of scattering elements are a plurality of identical scattering elements.

3. The antenna of claim 1, wherein the plurality of adjustable individual electromagnetic responses provide an effective medium response for the guided wave mode of the waveguide.

4. The antenna of claim 1, wherein the plurality of adjustable individual electromagnetic responses are a plurality of magnetic dipole radiation fields.

5. The antenna of claim 1, wherein the operating frequency is a microwave frequency.

6. The antenna of claim 5, wherein the microwave frequencies are Ka-band frequencies.

7. The antenna of claim 5, wherein the microwave frequency is a Ku-band frequency.

8. The antenna of claim 5, wherein the microwave frequency is a Q-band frequency.

9. The antenna of claim 1, wherein the inter-element spacing is less than a quarter of the free-space wavelength.

10. The antenna of claim 1, wherein the inter-element spacing is less than one fifth of the free-space wavelength.

11. The antenna of claim 1, wherein the waveguide is a substantially two-dimensional waveguide.

12. The antenna of claim 11, wherein the substantially two-dimensional waveguide is a parallel plate waveguide and the one or more conductive surfaces are upper conductors of the parallel plate waveguide.

13. The antenna of claim 1, wherein the waveguide comprises one or more substantially one-dimensional waveguides.

14. The antenna of claim 13, wherein the one or more substantially one-dimensional waveguides are a plurality of substantially one-dimensional waveguides forming a substantially two-dimensional antenna area.

15. The antenna of claim 13, wherein the one or more substantially one-dimensional waveguides comprise one or more microstrips.

16. The antenna of claim 15, wherein the one or more conductive surfaces are one or more respective upper conductors of the one or more microstrips.

17. The antenna of claim 15, wherein the one or more conductive surfaces are one or more conductive strips positioned parallel to one or more upper conductors of the one or more microstrips.

18. The antenna of claim 13, wherein the one or more substantially one-dimensional waveguides comprise one or more coplanar waveguides.

19. The antenna of claim 18, wherein the one or more conductive surfaces are located above the one or more coplanar waveguides.

20. The antenna of claim 13, wherein the one or more substantially one-dimensional waveguides comprise one or more closed waveguides.

21. The antenna of claim 20, wherein the one or more closed waveguides comprise one or more rectangular waveguides.

22. The antenna of claim 21, wherein the one or more rectangular waveguides comprise one or more double-ridged rectangular waveguides.

23. The antenna of claim 20, wherein the one or more conductive surfaces are one or more respective upper surfaces of the one or more closed waveguides.

24. The antenna of claim 20, wherein the one or more conductive surfaces are located above one or more respective upper surfaces of the one or more closed waveguides, and the one or more respective upper surfaces include a plurality of irises adjacent to the plurality of apertures within the one or more conductive surfaces.

25. The antenna of claim 1, wherein the electrically adjustable material is a liquid crystal material.

26. The antenna of claim 25, wherein the liquid crystal material is a nematic liquid crystal.

27. The antenna of claim 25, wherein the liquid crystal material is a dual frequency liquid crystal.

28. The antenna of claim 25, wherein the liquid crystal material is a polymer network liquid crystal.

29. The antenna of claim 25, wherein the liquid crystal material is a polymer dispersed liquid crystal.

30. The antenna of claim 1, wherein the plurality of apertures are arranged in rows and columns, and further comprising:

a plurality of bias circuits configured to provide respective biases between the one or more conductive surfaces and the respective plurality of conductive islands;

a set of row control lines, each row control line addressing a row of the plurality of bias circuits; and

a set of column control lines, each column control line addressing the plurality of bias circuits in a column.

31. The antenna of claim 30, wherein the plurality of bias circuits are arranged in rows and columns adjacent to the plurality of apertures, respectively.

32. The antenna of claim 1, wherein the plurality of apertures define a plurality of complementary metamaterial elements having a plurality of magnetic dipole responses to the magnetic field of the guided wave.

33. The antenna of claim 32, wherein the plurality of complementary meta-material elements are a plurality of complementary electrical LC meta-material elements.

34. The antenna of claim 32, wherein the plurality of magnetic dipole responses are a plurality of in-plane magnetic dipole responses oriented parallel to the one or more conductive surfaces.

35. The antenna of claim 34, wherein the plurality of in-plane magnetic dipole responses comprises a first plurality of in-plane magnetic dipole responses oriented in a first direction parallel to the one or more conductive surfaces and a second plurality of in-plane magnetic dipole responses oriented in a second direction perpendicular to the first direction and parallel to the one or more conductive surfaces.

36. A method of using the antenna of any of claims 1-35, comprising:

propagating the first guided wave to convey a first plurality of relative phases to a corresponding plurality of locations;

coupling with the first guided wave at a first set of locations selected from the respective plurality of locations to generate a first plurality of electromagnetic oscillations at the first set of locations, the first plurality of electromagnetic oscillations generating a first radiation field;

propagating a second guided wave to convey a second plurality of relative phases to the respective plurality of locations, wherein the second plurality of relative phases are the same as the first plurality of relative phases; and

coupling with the second guided wave at a second set of locations selected from the respective plurality of locations to generate a second plurality of electromagnetic oscillations at the second set of locations, the second plurality of electromagnetic oscillations generating a second radiation field different from the first radiation field.

37. The method of claim 36, wherein:

the first guided wave and the first radiation field define a first interference pattern, and the first set of locations selected from the respective plurality of locations correspond to a set of locations within a constructive interference region of the first interference pattern; and is

The second guided wave and the second radiation field define a second interference pattern different from the first interference pattern, and the second set of locations selected from the respective plurality of locations correspond to a set of locations within a constructive interference region of the second interference pattern.

38. A method of using the antenna of any of claims 1-35, comprising:

receiving a first free-space wave at a plurality of locations;

coupling with the first free-space wave at a first set of locations selected from the plurality of locations to generate a first plurality of electromagnetic oscillations at the first set of locations, the first plurality of electromagnetic oscillations generating a first guided wave having a first plurality of relative phases at the plurality of locations;

receiving a second free-space wave different from the first free-space wave at the plurality of locations;

coupling with the second free-space wave at a second set of locations selected from the plurality of locations to generate a second plurality of electromagnetic oscillations at the second set of locations that generate a second guided wave having a second plurality of relative phases at the plurality of locations, wherein the second plurality of relative phases are the same as the first plurality of relative phases.

39. The method of claim 38, wherein:

the first guided wave and the first free-space wave define a first interference pattern, and the first set of locations selected from the respective plurality of locations correspond to a set of locations within a constructive interference region of the first interference pattern; and is

The second guided wave and the second free-space wave define a second interference pattern different from the first interference pattern,

and the second set of locations selected from the respective plurality of locations corresponds to a set of locations within a constructive interference region of the second interference pattern.

40. A method of using the antenna of any of claims 1-35, comprising:

selecting a first antenna radiation pattern for the antenna; and

the antenna is adjustable in response to one or more control inputs, a first value of the one or more control inputs corresponding to the selected first antenna radiation pattern is determined.

41. A method as claimed in claim 40, wherein the antenna has a plurality of scattering elements having respective adjustable physical parameters as a function of the one or more control inputs.

42. The method of claim 41, wherein the determination of the first value of the one or more control inputs comprises:

determining a respective first value of the respective adjustable physical parameter to provide the selected first antenna radiation pattern; and

determining the first value of the one or more control inputs corresponding to the determined respective first value of the respective adjustable physical parameter.

43. The method of claim 41, wherein the respective adjustable physical parameter is a respective adjustable resonant frequency of the plurality of scattering elements.

44. The method of claim 41, wherein the one or more control inputs comprise a plurality of respective bias voltages for the plurality of scattering elements.

45. The method of claim 41, wherein the plurality of scattering elements are addressable in rows and columns, and the one or more control inputs comprise sets of row inputs and sets of column inputs.

46. The method of claim 41, wherein the plurality of scattering elements are fed by a set of feed lines having an adjustable gain, and the one or more control inputs comprise the adjustable gain.

47. The method of claim 41, further comprising:

providing the first value for the one or more control inputs of the antenna.

48. The method of claim 40, wherein the selection of the first antenna radiation pattern comprises a selection of an antenna beam direction.

49. The method of claim 48, wherein the antenna beam direction corresponds to a direction of a telecommunications satellite.

50. The method of claim 48, wherein the antenna beam direction corresponds to a direction of a telecommunications base station.

51. The method of claim 48, wherein the antenna beam orientation corresponds to an orientation of a telecommunications mobile platform.

52. The method of claim 40, wherein said selection of said first antenna radiation pattern comprises selection of one or more null directions.

53. The method of claim 40, wherein the selection of the first antenna radiation pattern comprises a selection of an antenna beam width.

54. The method of claim 40, wherein said selection of said first antenna radiation pattern comprises selection of a multi-beam arrangement.

55. The method of claim 40, wherein said selection of said first antenna radiation pattern comprises selection of an overall phase.

56. The method of claim 40, wherein said selection of said first antenna radiation pattern comprises selection of a polarization state.

57. The method of claim 56, wherein the selected polarization state is a circular polarization state.

58. The method of claim 56, wherein the selected polarization state is a linear polarization state.

59. The method of claim 40, further comprising:

selecting a second antenna radiation pattern different from the first antenna radiation pattern; and

determining a second value of the one or more control inputs corresponding to the selected second antenna radiation pattern.

60. The method of claim 59, further comprising:

providing the second value for the one or more control inputs of the antenna.

61. The method of claim 59 wherein the selection of the first antenna radiation pattern comprises a selection of a first antenna beam direction and the selection of the second antenna radiation pattern comprises a selection of a second antenna beam direction different from the first antenna beam direction.

62. The method of claim 61, wherein the selected first antenna radiation pattern provides a first polarization state corresponding to the first antenna beam direction, the selected second antenna radiation pattern provides a second polarization state corresponding to the second antenna beam direction, and the first polarization state is the same as the second polarization state.

63. The method of claim 62, wherein the first and second polarization states are circular polarization states.

64. The method of claim 62, wherein the first and second polarization states are linear polarization states.

65. The method of claim 61, wherein the first and second antenna beam directions correspond to directions of first and second remote communication satellites.

66. The method of claim 61, wherein the first and second antenna beam directions correspond to directions of first and second objects selected from a plurality of objects comprising a telecommunication satellite, a telecommunication base station, or a telecommunication mobile platform.

67. A method of using an antenna, comprising:

identifying a first target for a first antenna, the first antenna having a first adjustable radiation pattern responsive to one or more first control inputs, and the first antenna being the antenna of any one of claims 1-35; and

repeatedly adjusting the one or more first control inputs to provide a substantially continuous change in the first adjustable radiation pattern in response to a first relative motion between the first target and the first antenna.

68. The method of claim 67, wherein the first relative motion is translation of the first target.

69. The method of claim 67, wherein the first relative motion is a translation or rotation of the first antenna.

70. The method of claim 67, wherein the first relative motion is a combination of translation of the first target and translation or rotation of the first antenna.

71. The method of claim 67, wherein the substantially continuous variation of the first adjustable radiation pattern is selected to substantially maintain the first target within a main beam of the first adjustable radiation pattern.

72. The method of claim 67, wherein the substantially continuous variation of the first adjustable radiation pattern is selected to substantially maintain the first target at a null of the first adjustable radiation pattern.

73. The method of claim 67, wherein the substantially continuous variation of the first adjustable radiation pattern is selected to provide a substantially constant polarization state at the location of the first target.

74. The method of claim 73, wherein the substantially constant polarization state is a circular polarization state.

75. The method of claim 73, wherein the substantially constant polarization state is a linear polarization state.

76. The method of claim 67, wherein the first target is a telecommunications satellite.

77. The method of claim 67, wherein the first target is a telecommunications base station.

78. The method of claim 67, wherein the first target is a telecommunications mobile platform.

79. The method of claim 67, further comprising:

identifying a second target for a second antenna having a second adjustable radiation pattern responsive to one or more second control inputs, and the second antenna being the antenna of any one of claims 1-35; and

repeatedly adjusting the one or more second control inputs to provide a substantially continuous change in the second adjustable radiation pattern in response to a second relative motion between the second target and the second antenna.

80. The method of claim 79, wherein the first and second targets are members of a constellation of telecommunications satellites.

81. The method of claim 79, wherein the first relative motion is translation of the first target and the second relative motion is translation of the second target.

82. The method of claim 79, wherein:

the first relative motion is a combination of translation of the first target and translation or rotation of the first antenna;

the second relative motion is a combination of translation of the second target and translation or rotation of the second antenna; and

the translation or rotation of the first antenna is the same as the translation or rotation of the second antenna.

83. The method of claim 79, wherein the substantially continuous variation of the first adjustable radiation pattern is selected to substantially maintain the first target within a main beam of the first adjustable radiation pattern, and the substantially continuous variation of the second adjustable radiation pattern is selected to substantially maintain the second target within a main beam of the second adjustable radiation pattern.

84. The method of claim 83, further comprising:

adjusting the one or more first control inputs to position the second target substantially within the main beam of the first adjustable radiation pattern.

85. The method of claim 84, further comprising:

identifying a new target for a second antenna different from the first and second targets; and

adjusting the one or more second control inputs to position the new target substantially within the main beam of the second adjustable radiation pattern.

86. A system using the antenna of any of claims 1-35, comprising:

the antenna of any one of claims 1-35, being adjustable in response to one or more control inputs;

antenna control circuitry configured to provide the one or more control inputs; and

communication circuitry coupled with a feed structure of the antenna.

87. The system of claim 86, wherein the antenna has a plurality of scattering elements having respective adjustable physical parameters as a function of the one or more control inputs.

88. The system of claim 87, wherein the one or more control inputs comprise a plurality of respective bias voltages for the plurality of scattering elements.

89. The system of claim 87, wherein the plurality of scattering elements are addressable in rows and columns, and the one or more control inputs include sets of row inputs and sets of column inputs.

90. The system of claim 87, wherein the feed structure comprises a plurality of feeds with a corresponding plurality of amplifiers, and the one or more control inputs comprise adjustable gains of the corresponding plurality of amplifiers.

91. The system of claim 86, wherein the antenna control circuitry comprises:

a storage medium comprising a look-up table mapping sets of antenna radiation pattern parameters to corresponding sets of values of the one or more control inputs.

92. The system of claim 91, wherein the set of antenna radiation pattern parameters includes a set of antenna beam directions.

93. The system of claim 91, wherein the set of antenna radiation pattern parameters includes a set of antenna null directions.

94. The system of claim 91, wherein the set of antenna radiation pattern parameters includes a set of antenna beam widths.

95. The system of claim 91, wherein the set of antenna radiation pattern parameters includes a set of polarization states.

96. The system of claim 86, wherein the antenna control circuitry comprises:

processor circuitry configured to calculate a set of values for the one or more control inputs corresponding to a desired antenna radiation pattern parameter.

97. The system of claim 96, wherein the processor circuitry is configured to compute the set of values for the one or more control inputs by computing a holographic pattern corresponding to the desired antenna radiation pattern parameter.

98. The system of claim 86, further comprising:

a sensor unit configured to detect an environmental condition of the antenna.

99. The system of claim 98, wherein the sensor unit comprises one or more sensors selected from a GPS sensor, a thermometer, a gyroscope, an accelerometer, and a strain gauge.

100. The system of claim 98, wherein the environmental condition comprises a position, orientation, temperature, or mechanical deformation of the antenna.

101. The system of claim 98, wherein the sensor unit is configured to provide environmental condition data to the antenna control circuitry, and the antenna control circuitry comprises:

circuitry configured to adjust the one or more control inputs to compensate for a change in the environmental condition of the antenna.