Ravi Kumar Arya

A technique for designing flat lenses using artificially engineered materials

In this work, we present a new systematic technique for the design of a flat lens using modified commercial off-the-shelf (COTS) materials, as opposed to metamaterials that are often required in lens designs based on the Transformation Optics (TO) approach. While lens designs based on Ray Optics (RO) do not suffer from the above drawback of having to use metamaterials, they still require dielectric materials that may not be precisely available off-the-shelf. This paper describes a systematic procedure for realizing the desired materials by modifying the COTS types, and illustrates its application with a practical example.

Flat Lens Design Using Artificially Engineered Materials

In this work, we present a new systematic technique for the design of a flat lens using modified commercial off-the-shelf (COTS) materials, as opposed to metamaterials (MTMs) that are often required in lens designs based on the Transformation Optics (TO) approach. While lens designs based on Ray Optics (RO) do not suffer from the drawback of having to use metamaterials, they still require dielectric materials that may not be commercially available off-the-shelf. This paper describes a systematic procedure for realizing the desired materials by modifying the COTS types, and illustrates its application with some practical examples.

Statistical analysis of 3D-printed flat GRIN lenses

This paper presents the statistical analysis of a 3D printed flat lens by using the Polynomial Chaos Expansion (PCE) analysis technique. The flat lens is fabricated using the 3D printing technology and is based on the grading-index (GRIN) approach. It is composed of several concentric rings with graded relative permittivity, made of a single material with different air holes-host material volume ratio. We show that the hole size can have significant effect on the performance of the lens, especially on the focal distance. PCE analysis enables us also to determine the impact of each individual ring on the performance of the lens.

Low profile lens and reflectarray design for MM waves

In this work, we present low profile lens and reflectarray design for millimeter wave. We use artificially engineered dielectric materials (Dial-a-Dielectric) for these designs. We present comparison results with legacy designs that show comparable or better performance. We compare results of a flat lens using commercial off-the-shelf (COTS) materials, as opposed to metamaterials that are often required in lens designs based on the Transformation Optics (TO) approach. While lens designs based on Ray Optics (RO) do not suffer from the above drawback, they still require dielectric materials that may not be available off-the-shelf.

A new technique for efficient and accurate analysis of arbitrary 3D FSSs, EBGs and Metamaterials

In this paper we present a new numerically efficient and accurate technique for the analysis of doubly-infinite periodic arrays of elements, which find applications as Frequency Selective Surfaces (FSSs), Electronic Bandgap (EBGs) structures and Metamaterials (MTMs). The principal advantages of the proposed method, which is not based on the use of the Periodic Boundary Condition (PBC), are its versatility-since it can analyze 3D inhomogeneous elements-and its ability to handle arbitrary incidence angles in an efficient way, regardless of how large that angle is. It is well known that the Finite Difference Time Domain (FDTD)/PBC runs into difficulties for wide angles-requiring large computation times and becoming unstable for such angles.

A new computationally efficient technique for modeling periodic structures with applications to EBG, FSSs and metamaterials

In this paper we describe a novel technique for analyzing periodic structures that bypasses the use of the periodic boundary condition (PBC), and thus circumvents the slowness problem encountered in the construction of the periodic Greens function when using the Method of Moments (MoM), and the instability problem arising in the Finite Difference Time Domain (FDTD) analysis for wide angles of incidence. The basic strategy followed in the proposed approach is to generate the desired solution of the periodic problem by first analyzing a truncated version of the same, and then predicting the asymptotic limit of the solution of the truncated problem by using an efficient extrapolation technique that needs to work with only a moderate-size truncated structure to generate the desired solution of the doubly-infinite periodic configuration.

Offset-fed dielectric reflectarray antenna designs

In this work, we present two offset-fed dielectric reflectarray designs. Both reflectarrays feature broadband designs realized by using dielectric blocks backed by a PEC plane. One of these arrays uses a phase compensating flat lens to reduce the maximum permittivity of the dielectric blocks covering the PEC. We compare the results of both reflectarrays and list their benefits as compared to traditional reflectarrays that use resonant elements for their designs, which render them narrowband.

3D-printed millimeter wave lens antenna

In this work, we present a flat lens design using the Dial-a-Dielectric (DaD) and 3D-printing technique to realize the materials that are not available off-the-shelf. We design the proposed flat lens and compare its performance with that of the ray-optics (RO)-based lens. We find from the results that both designs show comparable performance.

Flat lens design using space-qualifiable multilayer frequency selective surfaces

This paper presents the design of a flat lens, which utilizes multilayer frequency selective surfaces (FSSs) in free space. The lens can be space-qualified since, unlike conventional designs for lenses, it does not need to use dielectric materials. The paper describes a systematic procedure for realizing the requisite radially varying phase shifts, by using locally-periodic multilayer FSSs to realize a lightweight, low profile and low-cost design.

Combining the FDTD algorithm with signal processing techniques for performance enhancement

The conventional FDTD technique utilizes time domain numerical convergence as the criterion for termination; hence, its computational cost is high when accurate results are needed for high Q systems; for low frequencies; or when we have to deal with dispersive media. In this paper, signal processing techniques are employed to reduce the computational cost associated with the FDTD, especially for the situations mentioned above, and render the technique more efficient than the conventional FDTD.