On the Use of Electromagnetic Inversion for Metasurface Design

We show that the use of the electromagnetic inverse source framework offers great flexibility in the design of metasurfaces. In particular, this approach is advantageous for antenna design applications where the goal is often to satisfy a set of performance criteria such as half power beamwidths and null directions, rather than satisfying a fully-known complex field. In addition, the inverse source formulation allows the metasurface and the region over which the desired field specifications are provided to be of arbitrary shape. Some of the main challenges in solving this inverse source problem, such as formulating and optimizing a nonlinear cost functional, are addressed. Lastly, some two-dimensional (2D) and three-dimensional (3D) simulated examples are presented to demonstrate the method, followed by a discussion of the method's current limitations.Comment: 13 page

On the Use of Focused Incident Near-Field Beams in Microwave Imaging

We consider the use of focused incident near-field (NF) beams to interrogate the object of interest (OI) in NF microwave imaging (MWI). To this end, we first discuss how focused NF beams can be advantageously utilized to suppress scattering effects from the neighbouring objects whose unknown dielectric properties are not of interest (i.e., undesired scatterers). We then discuss how this approach can also be helpful in reducing the required measured data points to perform imaging. Driven by the relation between the electromagnetic inverse source and inverse scattering problems, our approach emphasizes the importance of tailoring the induced contrast sources in the imaging domain through the utilized incident NF beams. To demonstrate this idea, we consider two recently-proposed NF beams, and simulate them for imaging applications. The first one is a subwavelength focused NF beam generated by a passive NF plate, and the other is a Bessel beam generated by a leaky radial waveguide. Simple imaging examples are considered to explore the potential advantages of this approach, in particular, toward mainly seeing the object of interest, and not the unknown undesired scatterers. The scope of this paper is limited to homogeneous dielectric objects for which the induced total field distributions in the interrogated objects are similar to the incident field distributions (e.g., those that satisfy the Born approximation). Simple inversion results for focused and non-focused beams are presented accompanied by discussions comparing the achieved reconstructed values

Introducing Climax: A novel strategy to a tri-wheel spiral robot

This paper describes a prototype and analytical studies of a tri-wheel spiral mobile robot. The robot can reach any desired point with a sequence of rotational movements. The robot has a simple actuation mechanism, consisting of three wheels mounted on a platform with axes fixed in 120? and a motor connected to each. Our approach introduces several new features such as simple repeated sequence of commands for steering and spiral motion, versus direct movement to target. The mathematical model of the robot is discussed, and a steering method is developed to achieve full motion capabilities. For a number of missions, it is shown experimentally that the proposed motion planning agrees well with the results

Introducing Glory: A Novel Strategy for an Omnidirectional Spherical Rolling Robot

This paper describes a prototype and analytical studies of a spherical rolling robot, a new design of an omnidirectional robot system. The robot can arbitrarily begin to move in any direction to the target, and autonomously roll and reach any desired position. Our design has considered a spherical robot with an internal mechanism for propulsion. The propulsion mechanism will dis- tribute weights radially along spokes fixed inside the sphere and enables the robot to accelerate, decelerate, and move with con- stant velocity. A mathematical model of the robot’s dynamic and motion was instructed. An algorithmic motion planning is devel- oped and, partly, pseudocode of that is presented. For a number of missions, it is shown experimentally that the model agrees well with the results

Introducing August: a novel strategy for an omnidirectional spherical rolling robot

This paper describes a prototype and analytical studies of a spherical rolling robot, a new design of an omnidirectional robot system. The robot can arbitrarily begin to move in any direction to the target, and autonomously roll and reach any desired position. Our design has considered a spherical robot with an internal mechanism for propulsion. The propulsion mechanism will distribute weights radially along spokes fixed inside the sphere and enables the robot to accelerate, decelerate, and move with constant velocity. A mathematical model of the robot’s dynamic and motion was instructed. An algorithmic motion planning is developed and, partly, pseudo-code of that is presented. For a number of missions, it is shown experimentally that the model agrees well with the results

A Diffusion Model for Multi-Layered Metasurface Unit Cell Synthesis

A deep learning approach based on a diffusion model is proposed to yield metasurface unit cell designs. This method takes desired two-port scattering parameters along with the frequency of operation in an attempt to synthesize three-layered metasurface unit cells. The core of this approach lies in casting the three-layered unit cell synthesis process as conditional three-channel binary image synthesis. The conditions are governed by the desired scattering parameters at a given frequency whereas the binary nature implies the presence and absence of metallic traces. Once synthesized, these unit cells are placed beside each other, without any further tuning, to form the final metasurface. The performance of the whole metasurface, for three different design scenarios, is then tested against full-wave simulation and/or experimental data