Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
10 results
Search Results
Item Active Multifunctional Reflective Metasurface for Linear to Cross and Linear to Circular Polarization Conversion Applications(Institute of Electrical and Electronics Engineers Inc., 2024) Goud, R.M.; Paul, P.; Majumder, B.; Kandasamy, K.A low-profile reconfigurable reflective metasurface capable of dynamically switching polarization conversion functionalities is proposed in this work. To realize this, a single-layered metasurface comprising tapered rectangular metal strips oriented diagonally with a Z-shaped conducting strip in the middle and L-shaped metal strips along the corners is etched on a substrate backed by a conducting layer. A diode is positioned at the center of the diagonally oriented structure, and the switching is controlled using a radial stub-based DC biasing circuit. When the PIN diode is turned OFF, the tunable metasurface reflects cross-polarized waves in the frequency spectrum ranging from 12.3- 15.5 GHz, whereas, in the ON state, it converts linear polarized waves into orthogonally polarized waves from 14.83- 15.83 GHz, also converts linear to left-handed and right-handed circular polarization with an axial ratio of less than 3 dB across four distinct frequency bands. The 45° orientation of the metallic layer makes the structure polarization-independent and can be best used for radar cross-section (RCS) reduction and future wireless and satellite communications simultaneously. © 2024 IEEE.Item High Transmissive Beam-Focusing Lenses based on All-dielectric Metasurface(Institute of Electrical and Electronics Engineers Inc., 2025) Goud, R.M.; Paul, P.; Majumder, B.; Kandasamy, K.This paper presents the design and analysis of a fully dielectric transmissive metasurface tailored for beam-focusing applications in the microwave frequency regime, specifically targeting operation at 20 GHz in K-band. The metasurface functions as a high-gain lens, employing flame-retardant resin to construct meta-atoms composed of cylindrical dielectric structures positioned on a dielectric substrate. By modulating the height of these cylinders, a continuous phase gradient ranging from 0° to 360° is achieved, enabling precise wavefront control for focusing incident electromagnetic waves along the broadside direction. Each meta-atom is optimized to maintain a transmittance greater than 90%, ensuring minimal energy loss during transmission. The required phase distribution across the metasurface is initially derived using MATLAB-based numerical synthesis, followed by full-wave parametric simulations in CST Studio Suite to correlate the geometrical variations with the desired phase shifts. Unlike conventional designs that rely on metallic inclusions or ground planes, this work introduces a novel all-dielectric architecture, offering advantages in cost-effective 3D printing fabrication, reduced weight, and enhanced efficiency. The 1D and 3D radiation patterns confirm the beam-focusing behavior of the metasurface, demonstrating its potential for integration into compact, high-performance lens-based systems for advanced wireless communication and radar applications. © 2025 IEEE.Item Transmissive All-Dielectric Metasurface for Beam-Splitting in the Ka-band(Institute of Electrical and Electronics Engineers Inc., 2025) Koilkonda, N.; Goud, R.M.; Paul, P.; Kandasamy, K.This paper presents a systematic design methodology and full-wave electromagnetic analysis of a high-efficiency, all-dielectric metasurface engineered for beam-splitting applications within the Ka-band spectrum. The proposed structure consists of a 15×15 transmissive array of subwavelength dielectric unit cells, meticulously optimized for operation at 30 GHz. By offering a lightweight, low-profile alternative to conventional bulky beamforming architectures, the metasurface enables efficient angular beam separation, generating two distinct far-field radiation lobes with a 30° angular divergence. The unit cell configuration incorporates a cylindrical structure positioned atop an ABS plastic substrate, achieving a transmittance exceeding 85% at the design frequency. A continuous 360° phase modulation is realized through precise tuning of the cylinder's radius, facilitating accurate phase-front manipulation. The phase synthesis process is implemented using MATLAB, while full-wave electromagnetic validations are conducted in CST Studio Suite. The demonstrated results underscore the metasurface potential for advanced beam-control applications, making it a promising candidate for next-generation satellite communications, radar systems, and 5G/mm wave networks. © 2025 IEEE.Item Characteristic mode-based compact circularly polarized metasurface antenna for in-band RCS reduction(Cambridge University Press Journals_subscriptions@cup.cam.ac.uk, 2020) Tharehalli Rajanna, P.K.; Rudramuni, K.; Kandasamy, K.This paper presents a novel design of a low profile circularly polarized (CP) metasurface (MTS) antenna with in-band radar cross-section (RCS) reduction property. The MTS is loaded as a superstrate on slot antenna and it can be viewed as a polarization-dependent MTS (PDMTS). The rectangular patch-based PDMTS is analyzed using characteristic mode analysis to find two orthogonal degenerate modes, which produces CP waves. Linearly polarized slot antenna is used to excite the PDMTS. The performance of PDMTS loaded slot antenna is analyzed numerically using full-wave analysis method. The PDMTS CP antenna is fabricated and its performance is tested experimentally. The proposed antenna has a compact structure and it has an overall size of (where is the free space wavelength). The measured results show that the PDMTS antenna achieves impedance bandwidth of 29.41, 3-dB axial ratio bandwidth of 9.05, broadside gain of 6.34 dB, and monostatic RCS reduction of at the resonant frequency of 5.86 GHz. The simulated results are in well agreement with the measured results and it is well suited for C-band Radar and Satellite communication. © © Cambridge University Press and the European Microwave Association 2019.Item Dielectric Metasurface Inspired Directional Multi-Port Luneburg Lens as a Medium for 5G Wireless Power Transfer - A Design Methodology(Institute of Electrical and Electronics Engineers Inc., 2022) Majumder, B.; Vinnakota, S.S.; Upadhyay, S.; Kandasamy, K.In this paper, a novel dielectric metasurface-inspired multi-beam directional Luneburg lens is proposed as a wireless power transfer medium at 5G mm-wave band. The lens is constructed using dielectric-based unit cells made up of a glide symmetric approach. It is connected with a set of microwave detector integrated multi-port tapered rectangular feeds to convert the received RF energy from different directions to DC power across a combined load. The proposed structure can be a potential candidate to harvest ambient energy from a wide coverage range of around 160° and produce a power conversion efficiency of about 76% for an input power of 14.9 dBm at 24 GHz. © 2009-2012 IEEE.Item Slot coupled dual band high gain circularly polarized metasurface antenna(John Wiley and Sons Inc, 2022) Tharehalli Rajanna, P.K.; Rudramuni, K.; Kandasamy, K.This article presents a slot coupled dual-band metasurface (MTS) based antenna with high gain and circular polarization characteristics. The MTS consists of two different unit cells, which give rise to two operating bands. The metasurface is excited by the slot aperture fed by a 50 Ω microstrip feed-line. The circular polarization is achieved by the diagonally oriented rectangular patch-based unit cells on top of the square substrate. Two orthogonal modes of MTS are required to produce circularly polarized waves, and these modes are excited by the slot aperture. The proposed MTS-inspired antenna is fabricated and experimentally validated. The experimentally verified impedance bandwidth of 33.71% in the lower frequency band and 5.35% in the upper-frequency band is achieved. The measured 3 dB (AR <3 dB)axial ratio bandwidth of 6.22% and 0.98% with a peak gain of 8.89 and 6.32 dBic is achieved with respect to 4.8 and 6.4 GHz resonant frequencies. © 2022 Wiley Periodicals LLC.Item Phase Gradient Metasurface Assisted Wideband Circularly Polarized Monopole Antenna(Electromagnetics Academy, 2023) Tharehalli Rajanna, P.K.; Kanadasamy, K.; Meveda, P.An asymmetric coplanar waveguide (CPW) fed wideband circularly polarized monopole antenna with a slot structure is proposed in this article. Phase gradient metasurface (PGM) is placed beneath the monopole to improve the gain. Circular polarization (CP) is achieved over wide bandwidth by combining the monopole and slot modes. The asymmetric CPW-fed monopole antenna provides CP at lower frequencies, and slot mode provides CP at higher frequencies. The asymmetric ground plane in the monopole and asymmetric strips in the slot are combined to produce wide axial ratio bandwidth. The proposed design’s detailed construction and operation are discussed with experimental validation. The proposed wideband CP antenna provides an impedance bandwidth of 95.46% and axial ratio bandwidth of 67.61%. The peak gain of 5.2 dBic is obtained at 2.35 GHz with 2 dB variation over operating bandwidth. The obtained radiation patterns provide good broadside radiation with better cross-polarization levels than co-polarization. © 2023, Electromagnetics Academy. All rights reserved.Item Indium Antimonide-Based All-Dielectric Metasurface Absorber at Terahertz Frequency for Refractive Index Sensing Applications(Institute of Electrical and Electronics Engineers Inc., 2024) Thomas, S.K.; Shenoy, A.; Satyanarayan, M.N.In this article, we present an indium antimonide (InSb)-based metasurface absorber (MA) using a complementary ring structure. The proposed MA exhibits absorption characteristics in the terahertz frequency range spanning from 1.0 to 2.2 THz. Within this frequency range, the MA demonstrates dual-band tunability, achieving approximately 100% absorption. Geometric parameters such as the outer ring radii, ring width, and InSb layer thickness are systematically adjusted to fine-tune the absorption frequency of the MA. In addition, we explore the refractive index sensing capabilities by introducing different refractive index materials into the air-filled complementary ring cavity. Notably, we achieve a peak refractive index sensitivity of 555 GHz per refractive index unit (RIU) for the first absorption peak at a minimum radius of 60 µm. © 2001-2012 IEEE.Item An ultra-broadband low profile modified chessboard metasurface with improved backscattering reduction(Elsevier B.V., 2025) Goud, M.G.; Paul, P.; Majumder, B.; Kandasamy, K.Building upon the concepts of polarization conversion and the mechanism of destructive interference, a single-layered ultra-broadband metasurface for radar cross-section (RCS) or backscattering reduction is proposed in this work. A diffusion-assisted checkerboard metasurface with re-tailored unit cells at the center leads to a significant improvement in the stealth characteristics. For this, a low profile and less complex unit cell is proposed, comprising a long metallic strip along the diagonal and two thin horizontal stubs at the edges. This unique arrangement exhibits more than 90% polarization conversion efficiency from 13.2 to 38.2 GHz. Modifying the geometry of central elements in a conventional checkerboard metasurface achieves a minimum of 15 dB RCS reduction from 10 to 38 GHz. Also, as we ascend the frequency spectrum, the beams are scattered in unintended directions with reduced signal strength. Notably, there is no beam in the boresight direction, as opposed to the conventional chessboard configurations. For off-normal incidences, the metasurface exhibits good angular stability, and a minimum of 10 dB backscattering reduction is maintained up to an incidence angle variation of 60°. The final optimized fabricated prototype exhibits measurement results that agree with the simulation results for normal and wide-angle incidences. © 2024 Elsevier B.V.Item An ultra-broadband polarization conversion metasurface for enhanced stealth and RCS mitigation in MIMO configurations(Elsevier GmbH, 2025) Goud, M.G.; Paul, P.; Majumder, B.; Kandasamy, K.A single-layer broadband metasurface for efficient cross-polarization conversion, aiming at improving the stealth performance of a MIMO antenna, is proposed in this work. A low-profile, minimally complex meta-atom and its mirror image are proposed, featuring a diagonal metallic strip and two narrow horizontal edge strips. This configuration achieves more than 90 % polarization conversion efficiency while maintaining an absolute 180-degree phase gradient between the reflected waves of the two meta-atoms. A chessboard metasurface with 10x10 elements, constructed with the proposed meta-atom and mirror image, is integrated with the slot antenna-based MIMO configuration. A slot antenna is orthogonally arranged to form a four-element MIMO configuration, ensuring high isolation exceeding 25 dB between the individual elements. The realized peak gain of this arrangement is 6.95 dBi radiating orthogonally. Monostatic, bistatic, and 3D scattering patterns of a MIMO configuration with and without metasurface are evaluated. Under oblique incidence, the metasurface demonstrates exceptional angular stability, maintaining a minimum RCS reduction of 10 dB for incidence angles up to 60°. The fabricated and optimized prototype exhibits measurement outcomes that closely correspond to the simulation results for normal and oblique incidence scenarios. © 2025 Elsevier GmbH