Faculty Publications
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Publications by NITK Faculty
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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 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