Abstract: Examples of the present invention include methods and apparatus for modification of electromagnetic waves, including lenses with generally parallel flat surfaces. Lenses may comprise metamaterials, dielectric materials (such as glass), plastics, and the like. Lenses may have an index profile corresponding to a coordinate transformation for the desired effect on the electromagnetic waves.

Abstract: A method for making an electromagnetic band gap structure includes performing a single full wave simulation for the structure using a computer to perform the simulation, extracting a multiple port scattering matrix based on the single full wave simulation using a computer, and measuring or estimating a transmission of waves across the body between a first port and a second port of the body. The body has multiple ports between the first port and the second port that are defined by scattering elements using the computer. The matrix may be reduced to a two by two matrix recursively one dimension at a time using the computer.

Abstract: Examples of the present invention include antennas and scattering elements having a metamaterial cloak configured so as to reduce effects on the operating parameters of a nearby antenna. For example, an antenna has an antenna frequency, and a cloak is disposed around the antenna having a frequency range in which the cloak is operative. The antenna frequency can lie outside the frequency range of the cloak, whereas the frequency of a second antenna lies within the frequency range of the cloak. In this case, the antenna is cloaked relative to the second antenna.

Abstract: Examples of the present invention include metamaterial lenses that allow enhanced resolution imaging, for example in MRI apparatus. An example metamaterial may be configured to have ?=?1 along three orthogonal axes. Superior performance was demonstrated using such improved designs, and in some examples, imaging resolution better than ?/500 was obtained. The use of one or more lumped reactive elements in a unit cell, such as one or more lumped capacitors and/or one or more lumped inductors, allowed unit cell dimensions and hence resolution to be dramatically enhanced. In some examples, a cubic unit cell was used with an essentially isotropic magnetic permeability of ?=?1 obtained at an operating electromagnetic frequency and wavelength (?).

Abstract: Examples of the present invention include metamaterials, including metamaterial lenses, having material properties that approximate the behavior of a material with low (0<n<1) effective index of refraction. Metamaterials may be designed and tuned using dispersion engineering to create a relatively wide-band low-index region. A low-index metamaterial lens created highly collimated beams in the far-field from a low-directivity antenna feed.

Abstract: Example apparatus have a radiation-receiving surface configured to receive electromagnetic radiation, including a sub-wavelength grating supported by a substrate. The sub-wavelength grating has a side-wall profile that may be configured and optimized to obtain desired spectral properties.

Abstract: A passive element is provided to facilitate passive detection of analytes, such as analytes, using an electromagnetic probe beam. The probe beam may be provided by a radar and/or lidar system. In one example, a passive element comprises a reference dipole and a detection dipole, the detection dipole having an associated analyte-sensitive element, such as a chemoresistive or bioresistive element. When the analyte-sensitive element is in a modified conducting state due to the presence of an analyte, the detection cross section is modified whereas a reference cross section is substantially unchanged by the presence of the analyte. A passive element may comprise a frequency selective surface, for example including a frequency-selective surface (FSS) embedded in a dielectric layer and using an analyte-sensitive impedance layer to modify the electromagnetic absorption properties, allowing analyte detection.

Abstract: An improved frequency selective surface (FSS) comprises a periodically replicated unit cell, the unit cell including a material having a first electrical conductivity in the presence of an external condition, and a second electrical conductivity in the absence of an external condition, or in the presence of a modified external condition. For example, the material may be a chemoresistive material, having an electrical conductivity that changes in the presence of a chemical or biological analyte, i.e. having a first value of electrical conductivity in the presence of the analyte, and a second value of electrical conductivity in the absence of the analyte.

Abstract: Examples of the present invention include methods and apparatus for modification of electromagnetic waves, including lenses with generally parallel flat surfaces. Lenses may comprise metamaterials, dielectric materials (such as glass), plastics, and the like. Lenses may have an index profile corresponding to a coordinate transformation for the desired effect on the electromagnetic waves.

Abstract: Examples of the present invention include antennas and scattering elements having a metamaterial cloak configured so as to reduce effects on the operating parameters of a nearby antenna. For example, an antenna has an antenna frequency, and a cloak is disposed around the antenna having a frequency range in which the cloak is operative. The antenna frequency can lie outside the frequency range of the cloak, whereas the frequency of a second antenna lies within the frequency range of the cloak. In this case, the antenna is cloaked relative to the second antenna.

Abstract: An improved frequency selective surface (FSS) comprises a periodically replicated unit cell, the unit cell including a material having a first electrical conductivity in the presence of an external condition, and a second electrical conductivity in the absence of an external condition, or in the presence of a modified external condition. For example, the material may be a chemoresistive material, having an electrical conductivity that changes in the presence of a chemical or biological analyte, i.e. having a first value of electrical conductivity in the presence of the analyte, and a second value of electrical conductivity in the absence of the analyte.

Abstract: A reconfigurable frequency selective surface (FSS) includes a plurality of conducting patches supported on the surface of a dielectric layer, with selectable electrical interconnections between the conducting patches so as to provide a desired characteristic. The reconfigurable FSS can be used in a reconfigurable artificial magnetic conductor (AMC). A reconfigurable AMC includes a dielectric layer, a conducting back-plane on one surface of the dielectric layer, and a reconfigurable FSS on the other surface of the dielectric layer. A reconfigurable AMC can be used as a dynamically reconfigurable ground plane for a low-profile antenna system.

Abstract: An example apparatus for facilitating detection of an analyte comprises a substrate supporting an antenna circuit that includes an antenna and a sensing element. The sensing element has a property, such as electrical resistance, that is modified by an interaction between the analyte and the sensing element. The antenna circuit generates transmitted radiation when irradiated with incident radiation, acting as a transponder, and the transmitted radiation has a spectral distribution correlated with a property of the sensing element so as to facilitate detection of the analyte. In some examples, the antenna circuit may be supported by a personal data card, such as a passenger ticket for a public transport system.

Abstract: An optimal configuration for at least one antenna and/or at least one frequency selective surface is generated. A configuration of elements is generated by selecting a simple configuration of at least one element and applying a genetic algorithm to the simple configuration to generate a configuration optimized for various characteristics. A stochastic process may be used to randomly select an arrangement of elements as the simple antenna configuration and to select elements that connect the randomly selected elements to produce a stochastic configuration to which the genetic algorithm is then applied. Alternatively, an iterated or semi-iterated process may be applied to the simple antenna configuration to produce a fractal or a semi-fractal configuration, respectively, to which the genetic algorithm is then applied. Also, the elements may be optimized independently.

Abstract: By configuring a high impedance frequency selective surface (HZ-FSS) structure for the appropriate values of surface impedance (surface resistance and surface reactance), a high frequency artificial ferrite metamaterial can be synthesized with almost any desired value of real and imaginary permeability. Materials with these properties have not previously been physically realizable at frequencies above 1 GHz.

Abstract: An antenna comprises an arrangement of electrically conducting segments, the arrangement including intersection points where two or more electrically conducting segments are in electrical communication. Example antennas include a plurality of capacitors located within some or all of the electrically conducting segments. Capacitance values can be determined using an optimization algorithm to obtain desired values of antenna resonance frequency (or frequencies), bandwidth, and/or radiation pattern, and may be adjusted in order to control an antenna parameter such as beam steering direction.

Abstract: An antenna array comprised of a fractile array having a plurality of antenna elements uniformly distributed along a Peano-Gosper curve. An antenna array comprised of an array having an irregular boundary contour comprising a plane tiled by a plurality of fractiles covering the plane without any gaps or overlaps. A method for generating an antenna array having improved broadband performance wherein a plane is tiled with a plurality of non-uniform shaped unit cells or an antenna array, the non-uniform shaped and tiling of the unit cells are then optimized. A method for rapidly forming a radiation pattern of a fractile array employing a pattern multiplication for fractile arrays wherein a product formulation is derived for the radiation pattern of a fractile array for a desired stage of growth. The pattern multiplication is recursively applied to construct higher order fractile array forming an antenna array.

Abstract: An antenna system includes an antenna element and an electromagnetic bandgap element proximate the antenna element wherein the electromagnetic bandgap element is optimized for narrow bandwidth operation thereby providing radiofrequency selectivity to the antenna system. Preferably the electromagnetic bandgap element is tunable such as through use of a bias-alterable dielectric substrate or other tuning mechanism. The design approach also provides a means of creating an ultra-thin low-profile narrowband tunable channel selective antenna system suitable for low frequency applications.

Abstract: A reconfigurable frequency selective surface (FSS) includes a plurality of conducting patches supported on the surface of a dielectric layer, with selectable electrical interconnections between the conducting patches so as to provide a desired characteristic. The reconfigurable FSS can be used in a reconfigurable artificial magnetic conductor (AMC). A reconfigurable AMC includes a dielectric layer, a conducting back-plane on one surface of the dielectric layer, and a reconfigurable FSS on the other surface of the dielectric layer. A reconfigurable AMC can be used as a dynamically reconfigurable ground plane for a low-profile antenna system.

Abstract: By configuring a high impedance frequency selective surface (HZ-FSS) structure for the appropriate values of surface impedance (surface resistance and surface reactance), a high frequency artificial ferrite metamaterial can be synthesized with almost any desired value of real and imaginary permeability. Materials with these properties have not previously been physically realizable at frequencies above 1 GHz.