Dr. Khushboo Singh
School of Electrical and Data Engineering, University of Technology Sydney, Sydney, New South Wales, Australia
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Academic Career Length
6Years (2021-Present)
(Calculated once Scilit publication data is synced: current year − year of first publication + 1)
Representative Publications
View All Publications22 May 2023 in IEEE Access
Journal Article
This article reviews the latest developments of beam steering antennas that are entirely passive to realize interference-free, power-efficient, and highly secured end-to-end wireless communication. We briefly introduce metamaterials and metasurfaces, a timely advanced topic in electromagnetics (EM) and optics. Mathematical formulas associated with the design of beam steering metasurfaces have been numerically explained. In addition, reflect and transmit array antennas are also discussed for an in-depth understanding of beam scanning principles in elevation and azimuth planes. We then provide intuitive design examples and discuss three broad classes of the latest beam scanning antenna systems, namely i) Reflectarrays, ii) Transmitarrays, and iii) Near-Field Meta-Steering antennas that are available in up-to-date literature. The third category’s unprecedented scanning performance and aesthetically compact size are elucidated compared to previous antenna systems, such as reflector dishes or large phased arrays. Alongside the working principles, the trade-offs for the scanning techniques, operation, and physical size of each antenna type are also discussed. Towards the end, an evaluative conclusion with a comparative discussion on the beam-steering antenna systems is provided. Future research directions considering mass-market demands are also indicated.
26 July 2021 in IEEE Access
Journal Article
Khushboo SinghMAMuhammad Usman Afzal
Muhammad Usman AfzalKEKaru P. Esselle
Karu P. EsselleWe investigate the aptness of various 4 th order (90°) rotationally symmetric phase-transforming cells for the upper phase-gradient metasurface, which always receives an oblique incidence wave from the lower metasurface in a Near-Field Meta-Steering system. A comprehensive study on the behavior of various phase-transforming cells and corresponding supercells when a rotating oblique plane wave impinges on them is presented. First, we select the supercell with high transmission in the desired output Floquet modes, for both TE and TM input modes, when an oblique incidence wave is rotated. The selected supercell is then optimized using Floquet analysis in conjunction with particle swarm optimization (PSO). All the undesired modes are successfully suppressed below -32 dB in the optimized supercell, and the predicted broadside radiation pattern is free of spurious grating lobes. A Near-Field Meta-Steering system with an aperture diameter of 7.3λ 0 (110mm @ 20 GHz) is presented. It has a pair of optimized phase-gradient metasurfaces and a dipole antenna array. A maximum peak directivity of 24.2 dB is achieved when the beam is in the broadside direction. The proposed steering system is capable of scanning a conical range with an apex angle of 126° when a 6 dB reduction in peak directivity is allowed. For a 3 dB variation in the peak directivity, the corresponding apex angle is 103°.
Journal Article
Khushboo SinghMSMondeep Saikia
Mondeep SaikiaKTKarthick Thiyagarajan
Karthick ThiyagarajanDTDushmantha Thalakotuna
Dushmantha ThalakotunaKEKaru P. Esselle
Karu P. EsselleSKSarath Kodagoda
Sarath KodagodaIn this paper, we propose a reconfigurable intelligent surface (RIS) that can dynamically switch the transmission and reflection phase of incident electromagnetic waves in real time to realize the dual-beam or quad-beam and convert the polarization of the transmitted beam. Such surfaces can redirect a wireless signal at will to establish robust connectivity when the designated line-of-sight channel is disturbed, thereby enhancing the performance of wireless communication systems by creating an intelligent radio environment. When integrated with a sensing element, they are integral to performing joint detection and communication functions in future wireless sensor networks. In this work, we first analyze the scattering performance of a reconfigurable unit element and then design a RIS. The dynamic field scattering manipulation capability of the RIS is validated by full-wave electromagnetic simulations to realize six different functions. The scattering characteristics of the proposed unit element, which incorporates two p-i-n diodes have been substantiated through practical implementation. This involved the construction of a simple prototype and the subsequent examination of its scattering properties via the free-space measurement method. The obtained transmission and reflection coefficients from the measurements are in agreement with the anticipated outcomes from simulations.
Journal Article
Metasurfaces have emerged as game-changing technology ranging from microwaves to optics. This article provides a roadmap to the evolution of electromagnetic metasurfaces with a focus on their synthesis techniques, materials used for their design and their recent and futuristic applications. A broad classification is provided, and the design principle is elaborated. The efficient and economical use of available computational resources is imperative to work with state-of-the-art metasurface systems. Hence, optimization becomes an integral part of metasurface design. Several optimization methodologies reported to date have been discussed. An extensive study on the current research database gathered a comprehensive understanding of meta-atom topologies and the preferred fabrication technologies. The study concludes with a critical analysis and highlights existing and future research challenges to be addressed.
8 March 2022 in Scientific Reports
Journal Article
Near-Field Meta-Steering (NFMS) is a constantly evolving and progressively emerging novel antenna beam-steering technology that involves an elegant assembly of a base antenna and a pair of Phase-Gradient Metasurfaces (PGMs) placed in the near-field region of the antenna aperture. The upper PGM in an NFMS system receives an oblique incidence from the lower PGM at all times, a fact that is ignored in the traditional design process of upper metasurfaces. This work proposes an accurate optimization method for metasurfaces in NFMS systems to reduce signal leakage by suppressing the grating lobes and side lobes that are innate artifacts of beam-steering. We detail the design and optimization approach for both upper and lower metasurface. Compared to the conventionally optimized compact 2D steering system, the proposed system exhibits higher directivity and lower side-lobe and grating lobe levels within the entire scanning range. The broadside directivity is 1.4 dB higher, and the side-lobe level is 4 dB lower in comparison. The beam-steering patterns for the proposed 2D compact design are experimentally validated, and the measured and predicted results are in excellent concurrence. The versatile compatibility of truncated PGMs with a low gain antenna makes it a compelling technology for wireless backhaul mesh networks and future antenna hardware.
Journal Article
MNMaira Islam Nabeel
Maira Islam NabeelKhushboo SinghMAMuhammad Usman Afzal
Muhammad Usman AfzalDTDushmantha Thalakotuna
Dushmantha ThalakotunaKEKaru P. Esselle
Karu P. EsselleEfficient beam steerable high-gain antennas enable high-speed data rates over long-distance networks, including wireless backhaul, satellite communications (SATCOM), and SATCOM On-the-Move. These characteristics are essential for advancing contemporary wireless communication networks, particularly within 5G and beyond. Various beam steering solutions have been proposed in the literature, with passive beam steering mechanisms employing planar metasurfaces emerging as cost-effective, power-efficient, and compact options. These attributes make them well-suited for use in confined spaces, large-scale production and widespread distribution to meet the demands of the mass market. Utilizing a dual-band antenna terminal setup is often advantageous for full duplex communication in wireless systems. Therefore, this article presents a comprehensive review of the dual-band beam steering techniques for enabling full-duplex communication in modern wireless systems, highlighting their design methodologies, scanning mechanisms, physical characteristics, and constraints. Despite the advantages of planar metasurface-based beam steering solutions, the literature on dual-band beam steering antennas supporting full duplex communication is limited. This review article identifies research gaps and outlines future directions for developing economically feasible passive dual-band beam steering solutions for mass deployment.
About Me
Khushboo Singh is a post-doctoral Research Associate at the University of Technology Sydney. She completed her doctoral degree in Electronics Engineering from Macquarie University, Australia, in 2021.
Dr. Khushboo has received several awards and scholarships during her academic and professional career. She was awarded a silver medal on the completion of her undergraduate degree. She received a prestigious LNMIIT scholarship during her master's studies from 2012 to 2014 and a highly competitive Australian government-funded iRTP scholarship for her Ph.D. She received the Choose Maths grant in 2017 and the NAWA PROM exchange funding in 2022. She also received a grant of $26K under the Australian Postgraduate Research Intern (APR) program, and her team received a grant of $24K for research collaboration under the ``Australia-Germany Joint Research Cooperation Scheme''.
Antennas and Evolutionary Optimization Algorithms are the two key areas that best encapsulate the scope of her recent research activities. She is currently working on developing and optimizing satellite-terminal antenna technology for LEO and MEO. Her research interests include antennas, phase-gradient metasurfaces, beam-steering antennas, frequency-selective surfaces, evolutionary optimization methods, artificial intelligence, machine learning in electromagnetics, surface electromagnetics, waveguide polarizers, couplers, and frequency-modulated continuous wave radar.