Anuj Y. Modi

Bio: Anuj Y. Modi is an academic researcher from Arizona State University. The author has contributed to research in topics: Radiation pattern & Antenna measurement. The author has an hindex of 7, co-authored 26 publications receiving 287 citations. Previous affiliations of Anuj Y. Modi include Nirma University of Science and Technology.

Novel Design of Ultrabroadband Radar Cross Section Reduction Surfaces Using Artificial Magnetic Conductors

Abstract: A novel technique for designing ultrabroadband radar cross section (RCS) reduction surfaces using artificial magnetic conductors (AMCs) is proposed in this paper. This technique overcomes the fundamental limitation of the conventional checkerboard design where the reflection phase difference of (180±37)° is required to achieve 10-dB RCS reduction. Initially, a planar surface for broadband RCS reduction is designed with two properly selected AMCs in a blended checkerboard architecture. A 10-dB RCS reduction is observed for more than 83% of the bandwidth (3.9–9.45 GHz) with this blended checkerboard design. After modifying the blended checkerboard design using the proposed novel technique, the 10-dB RCS reduction bandwidth increased to 91% fractional bandwidth (3.75–10 GHz) as the criteria of (180 ± 37)° reflection phase difference is no longer required. Measured data show an excellent agreement between the predicted, simulated, and measured data. Bistatic performance of the surface at various frequencies is also presented. Key steps for designing ultrabroadband RCS reduction checkerboard surface are summarized.

New Class of RCS-Reduction Metasurfaces Based on Scattering Cancellation Using Array Theory

Abstract: A technique to synthesize a new category of radar cross-section (RCS)-reduction metasurfaces is presented. The appealing feature of the proposed technique is that by representing the generalized Snell–Descartes’ law of reflection in the form of array factor, it unifies the two most widely studied and well-established modern RCS-reduction methods: checkerboard metasurfaces and gradient index metasurfaces. More importantly, it refines the concepts of both of these metasurfaces and overcomes numerous limitations associated with them. It can synthesize the RCS-reduction metasurfaces which can be placed along with almost any existing metasurface, without replacing the original metasurface that may be designed to serve a specific purpose, to reduce its RCS. The proposed technique is fundamentally based on scattering cancellation, and it is validated using artificial magnetic conductor technology for several configurations. Moreover, a phasor representation is developed and implemented for complex configurations to make the synthesis simpler and more insightful. Finally, to display the versatility of the proposed technique, an example of RCS-reduction metasurface has been synthesized and introduced to an existing high-gain metasurface ground plane available in the literature. This paper is confined to the conventional specular direction.

Cylindrically Curved Checkerboard Surfaces for Radar Cross-Section Reduction

Abstract: Checkerboard surfaces, for radar cross-section (RCS) reduction, utilizing artificial magnetic conductor structures on flexible cylindrically curved ground planes are introduced. The RCSs of cylindrical checkerboard surfaces are examined for two different radii of curvature. Wideband curved checkerboard surfaces are evaluated under normal incidence for HH and VV polarizations. Simulated bistatic RCS patterns of the cylindrical checkerboard surfaces are presented, discussed, and justified, and the backscattering is compared with measurements. A very good agreement is observed.

Predicting the Performance of Pyramidal and Corrugated Horn Antennas Using ANFIS

Abstract: This letter presents the development of an adaptive neuro fuzzy inference system (ANFIS)-based model for predicting the performance of a pyramidal and a conical corrugated horn antennas. Different ANFIS-based models were developed. Using these models, horn return-loss characteristics and radiation patterns (copolarization and cross-polarization) can be obtained with great accuracy for any combination of design parameters. The results obtained using ANFIS models were compared to that of the commercial horn antenna design software and found in close agreement. The advantage of the proposed method lies with the fact that, with less time and minimum computational resources, the return-loss and radiation characteristics of a horn antenna under test can be obtained with high degree of accuracy.

Design and Evaluation of Reconfigurable Intelligent Surfaces in Real-World Environment.

Abstract: Reconfigurable intelligent surfaces (RISs) have promising coverage and data rate gains for wireless communication systems in 5G and beyond. Prior work has mainly focused on analyzing the performance of these surfaces using computer simulations or lab-level prototypes. To draw accurate insights about the actual performance of these systems, this paper develops an RIS proof-of-concept prototype and extensively evaluates its potential gains in the field and under realistic wireless communication settings. In particular, a 160-element reconfigurable surface, operating at a 5.8GHz band, is first designed, fabricated, and accurately measured in the anechoic chamber. This surface is then integrated into a wireless communication system and the beamforming gains, path-loss, and coverage improvements are evaluated in realistic outdoor communication scenarios. When both the transmitter and receiver employ directional antennas and with 5m and 10m distances between the transmitter-RIS and RIS-receiver, the developed RIS achieves $15$-$20$dB gain in the signal-to-noise ratio (SNR) in a range of $\pm60^\circ$ beamforming angles. In terms of coverage, and considering a far-field experiment with a blockage between a base station and a grid of mobile users and with an average distance of $35m$ between base station (BS) and the user (through the RIS), the RIS provides an average SNR improvement of $6$dB (max $8$dB) within an area $> 75$m$^2$. Thanks to the scalable RIS design, these SNR gains can be directly increased with larger RIS areas. For example, a 1,600-element RIS with the same design is expected to provide around $26$dB SNR gain for a similar deployment. These results, among others, draw useful insights into the design and performance of RIS systems and provide an important proof for their potential gains in real-world far-field wireless communication environments.

Principles Of Optics Electromagnetic Theory Of Propagation Interference And Diffraction Of Light

Abstract: Thank you for reading principles of optics electromagnetic theory of propagation interference and diffraction of light. As you may know, people have search hundreds times for their favorite novels like this principles of optics electromagnetic theory of propagation interference and diffraction of light, but end up in harmful downloads. Rather than enjoying a good book with a cup of coffee in the afternoon, instead they are facing with some infectious bugs inside their computer.

Metasurfaces and their applications

Abstract: Metasurfaces are a topic of significant research and are used in various applications due to their unique ability to manipulate electromagnetic waves in microwave and optical frequencies. These artificial sheet materials, which are usually composed of metallic patches or dielectric etchings in planar or multi-layer configurations with subwavelength thickness, have the advantages of light weight, ease of fabrication, and ability to control wave propagation both on the surface and in the surrounding free space. Recent progress in the field has been classified by application and reviewed in this article. Starting with the development of frequency-selective surfaces and metamaterials, the unique capabilities of different kinds of metasurfaces have been highlighted. Surface impedance can be varied and manipulated by patterning the metasurface unit cells, which has broad applications in surface wave absorbers and surface waveguides. They also enable beam shaping in both transmission and reflection. Another important application is to radiate in a leaky wave mode as an antenna. Other applications of metasurfaces include cloaking, polarizers, and modulators. The controllable surface refractive index provided by metasurfaces can also be applied to lenses. When active and non-linear components are added to traditional metasurfaces, exceptional tunability and switching ability are enabled. Finally, metasurfaces allow applications in new forms of imaging.

Novel Design of Ultrabroadband Radar Cross Section Reduction Surfaces Using Artificial Magnetic Conductors

Abstract: A novel technique for designing ultrabroadband radar cross section (RCS) reduction surfaces using artificial magnetic conductors (AMCs) is proposed in this paper. This technique overcomes the fundamental limitation of the conventional checkerboard design where the reflection phase difference of (180±37)° is required to achieve 10-dB RCS reduction. Initially, a planar surface for broadband RCS reduction is designed with two properly selected AMCs in a blended checkerboard architecture. A 10-dB RCS reduction is observed for more than 83% of the bandwidth (3.9–9.45 GHz) with this blended checkerboard design. After modifying the blended checkerboard design using the proposed novel technique, the 10-dB RCS reduction bandwidth increased to 91% fractional bandwidth (3.75–10 GHz) as the criteria of (180 ± 37)° reflection phase difference is no longer required. Measured data show an excellent agreement between the predicted, simulated, and measured data. Bistatic performance of the surface at various frequencies is also presented. Key steps for designing ultrabroadband RCS reduction checkerboard surface are summarized.

Design of Checkerboard AMC Structure for Wideband RCS Reduction

Abstract: In this paper, we propose a method for designing checkerboard surfaces using strategically placed artificial magnetic conductors (AMCs) for wideband radar cross section (RCS) reduction. The theoretical analysis shows that the reflection phases of the two AMCs should be linear. The cancelation conditions of checkerboard structure are analytically derived using an equivalent transmission line model, and the ideal impedance conditions of the two AMCs are obtained, which serve as guidance to select patterns of two AMCs unit. A planar checkerboard surface with two kinds of AMC elements is designed for wideband RCS reduction. A 10 dB RCS reduction is observed for approximately 91.5% of the relative bandwidth (3.77–10.14 GHz) under normal incidence. A prototype of the proposed checkerboard surface is fabricated, and the measurements results show good coincidence with the synthetic studies. The bistatic RCS of the checkerboard surface is considered for both transverse electric and transverse magnetic polarizations under oblique incidence.