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Transmitarray antenna performance is limited by the amplitude and phase uniformity of the illumination source. Horns are a common feed-source for transmitarrays, but require large separation distances in order to provide uniform illumination, thus, limiting the ability to realize low-profile horn-fed transmitarray systems. In order to overcome this challenge, transformation optics inspired lenses...
Through the careful consideration of field enhancement observed in individual unit cells, metamaterials can be designed for use in high power microwave (HPM) applications. However, power handling considerations are only one aspect of any metamaterial design's performance. Presented here are two metamaterial unit cell geometries which feature reconfigurable reflection phase behaviors intended for HPM...
A metamaterial design that can rapidly reconfigure its reflection phase angle and safely operate under high incident field strengths is presented for use in a high power microwave (HPM) reflectarray system. The design offers switching between reflection phase angles to allow for beam control with a stationary reflector and feed horn. Two variations of the design are presented which offer (a) fixed...
A metamaterial design that can rapidly reconfigure its reflection phase angle and safely operate under high incident field strengths is presented for use in a high power microwave (HPM) reflectarray system. The design offers switching between three sufficiently unique reflection phase angles to allow for beam control with a stationary reflector and feed horn. The metamaterial unit cell is fairly lightweight...
For simplicity, most ultra-wideband aperiodic array layout design approaches use only isotropic sources as elements during optimization. However, since the selected antenna element can have a large impact on the total radiation pattern of the final array, it would be beneficial in such cases to use realistic antenna element patterns when designing array layouts. In this paper, a realistic spiral antenna...
An overview of current high performance, nature-inspired ultra-wideband antenna array design techniques is given. The polyfractal, raised-power series (RPS), compact direct, and aperiodic tiling methods are discussed, which utilize nature-inspired optimization strategies such as the genetic algorithm or the recently developed covariance matrix adaptation evolutionary strategy. These methods have yielded...
A new method for designing broadband transmission gratings with wide field of view for solar cell applications is proposed. The method is based on forming the sidewalls of the gratings according to polynomial functions. To achieve the optimal response, the roots of the polynomial are optimized. This method allows for generating complex sidewall profiles while keeping the number of variables at a manageable...
In this communication, we present further explorations of the performance of antennas made of bundles of CNT dipoles in the terahertz regime. Results are based on numerical simulations by means of thin-wire integral equations, which constitute a computationally fast and accurate method of analysis. Properly arranged, cylindrical as well as rectangular bundles are able to resonate in the terahertz...
Over the past few decades, much research has been invested in the exploration of wideband and ultrawideband (UWB) antenna arrays. The goals of such array designs are to determine the best element arrangements that yield radiation patterns possessing the highest degrees of sidelobe suppression and no grating lobes over the largest possible operating bandwidths. It has been recently shown that nature-inspired...
In this paper we utilize phenomenological models based on a Lorentz-Drude damped oscillator for describing the optical properties of an arbitrary solid. A computationally efficient method of including these constitutive parameters in a full-wave electromagnetic solver is presented through the use of equivalent circuit models and integral equations. These models can be represented as equivalent electric...
In this paper, the TD-EFIE is utilized for accurately and efficiently simulating the electromagnetic properties of CN antennas. Results presented here demonstrate the advantages of using a formulation based on the TD-EFIE. The physical insight provided by the method is also briefly discussed.
This paper summarizes the research and development of multispectral infrared mirror designs based on the surface patterning of coating materials. Three-dimensional structures can be etched into the coating materials to create infrared devices capable of meeting a wide variety of different multispectral performance requirements. The design methodology developed in this work is based on optimizing the...
A nature-inspired optimization method is applied in designing metasurfaces with customized electromagnetic properties. Characterized by their surface impedances, FSSbased metasurfaces such as soft and hybrid surfaces were realized within the desired frequency band, demonstrating the efficiency of the proposed design methodology. The optimized metasurfaces were further matched to a homogeneous metamaterial...
We have proposed a single-material all-dielectric optical filter design to provide efficient transmission of light using aSi. An angularly independent low-pass optical filter was presented designed using a GA which optimized for material thickness, sidewall profile and periodicity. A traditional thin-film multilayer filter was designed, which produced comparable results. Further study could be done...
Hybrid-mode horns such as corrugated horns, strip loaded horns and dielectric loaded horns have been used for satellite antennas due to their low cross-polarized radiation. Furthermore, horns that support the balanced hybrid-mode can behave as either soft or hard horns, providing low sidelobes or high aperture efficiency. Although corrugated horns have found wide use in satellite antennas, dielectric...
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