Faculty Publications
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Publications by NITK Faculty
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Item A Copper Strip Array Loaded Multiband Square Slot Antenna(Institute of Electrical and Electronics Engineers Inc., 2020) Paul, P.; Kandasamy, K.; Sharawi, M.S.A simple copper strip array loaded multiband square slot antenna with microstrip line feed is proposed in this paper. The slot antenna is designed to radiate at 2.28 GHz. The slot is loaded with a uniform array of rectangular copper strips to produce other resonances at 2.2 GHz, 3.4 GHz, 4.6 GHz, 5.4 GHz, 6.6 GHz. The proposed antenna is modeled and simulated using HFSS. The antenna prototypes are fabricated and tested. Good agreement is obtained between the measured and simulated results. The surface current distributions at the various resonant frequencies are simulated. The principle of operation is explained based on the distributions obtained and using analytic equations. An equivalent circuit model is also studied. Impedance bandwidths of 500 MHz, 300 MHz, 600 MHz, 400 MHz, 600 MHz and a gain of above 3 dB is obtained at the five resonant frequencies. © 2020 EurAAP.Item Reconfigurable Multifunctional Metasurface for Wideband Polarization Conversion(Institute of Electrical and Electronics Engineers Inc., 2024) Goud, M.G.; Duggal, A.; Paul, P.; Kandasamy, K.Multifunctional polarization converters have been in high demand due to the lack of features for polarization conversion in the existing designs. The need for integration of active elements to develop reconfigurable metasurfaces helps develop multifunctional metasurfaces. However, the challenge still lies in developing a cost-efficient and feasible design that can operate over a very wide band of frequencies while providing multifunctional polarization conversion over the entire operating bandwidth. The design consists of three layers with a PIN diode integrated into the upper patch layer. Polarization conversion functionalities are obtained depending upon the state of the PIN diode. The proposed metasurface operates over 8.4 GHz- 14.13 GHz with a relative bandwidth of 50.87%. When the integrated PIN diode is turned OFF, cross-polarization conversion is obtained over this entire frequency range, exhibiting a conversion ratio (PCR) of >90%. When the PIN diode is switched ON, multiple polarization conversions are obtained within the frequency band of operation. Cross Polarization conversion is observed from 10.9 GHz to 14.2 GHz with a relative bandwidth of 26.3% and PCR>90%, and linear to circular polarization is observed in two bands from 8.1277 GHz -8.231 GHz and 9.23 GHz-10.4 GHz. © 2024 IEEE.Item A Tunable Frequency Selective Surface for Band Pass and Band Stop Applications(Institute of Electrical and Electronics Engineers Inc., 2024) Goud, M.G.; Paul, P.; Majumder, B.; Kandasamy, K.In this work, a low-profile reconfigurable frequency selective surface capable of dynamically tuning the frequencies for band-pass and band-stop filtering applications is proposed. To realize this, a single-layered FSS is designed with tapered metal strips separated by a central gap and square metal patches positioned at the corners. Two PIN diodes are embedded in both the top and bottom layers. They are positioned at the center of the 45°-oriented metal strips, and for the frequency tuning, at least one of the diodes must be in the ON state. When both the diodes are ON, the tunable metasurface exhibits band-pass characteristics from 8.56- 14.8 GHz and band-stop characteristics from 3.08- 5.2 GHz. Similarly, when the PIN diode is in OFF state, the transmission window is from 6.25-8.1 GHz and band-stop window is from 3.1-4.3 GHz. With these transmission and reflection characteristics, the proposed work is best suitable for wireless and radar applications. © 2024 International Radio Science Union (URSI).Item Reflective Metasurface for Ultra-Wide Band Polarization Conversion with good Angular Stability(Institute of Electrical and Electronics Engineers Inc., 2024) Joshi, R.; Goud, R.M.; Paul, P.; Kandasamy, K.This paper presents a compact metasurface that provides linear to circular polarization over an ultra-wide band range of frequencies with good angular stability. The unit cell consists of a metallic circular ring with tapered rectangular metallic strips connected along the diagonal. The proposed Polarization Conversion Metasurface (PCM) consists of a 10x10 array of the unit cells and exhibits polarization conversion over a wide bandwidth of 11.5 GHz -32 GHz (94.25%). The design is validated using CST simulations and graphs are plotted for the various metrics evaluated. The proposed design exhibits angular stability till the 15° of angle of incidence. Owing to its high angular stability and ultra-wide band operation covering C, X, Ku, K bands, the proposed design is best suited for future wireless communication, MIMO communication and for RCS reduction and stealth applications. © 2024 IEEE.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 Novel Reflective Phased Meta-Atom Array for Beam Forming along Multiple Planes(Institute of Electrical and Electronics Engineers Inc., 2024) Paul, P.; Goud, M.; Kandasamy, K.; Majumder, B.In this paper a novel beam-forming technique for focused microwave power transmission (MPT) at specific frequencies that enables far-field transmission at three directions in the elevation plane is proposed. A simple and planar phased metasurface comprising of an array of subwavelength meta-unit cells is designed to focus the microwave energy at 4.2 GHz at desired angles in the azimuthal and elevation planes. The beam formed is made to focus energy at 0° by a suitably designed meta surface. The phase profile of the meta-atom array is then suitably tuned, to split the RF energy at elevation angles of 70° and -70° directions in azimuthal planes of 45°, 135°,225° and 315°. This ensures the compatibility of the designed reflective array surface with antenna radiators and hence, allows for the availability of power at different directions of focus. This functionality can be used to focus or deflect power in case of sensors placed at different locations in the far-field proximity of the main radiator. A patch antenna radiating at 4.2 GHz is used to conduct the simulation study using CST Microwave Studio. © 2024 IEEE.Item Dual-Functional Reflective-Metastructure Array for Polarization Conversion and Stealth Application(Institute of Electrical and Electronics Engineers Inc., 2024) Madhusudhan Goud, R.; Paul, P.; Kandasamy, K.; Majumder, B.This work proposes a compact, single-layered dualfunctional reflective meta-structure array to convert incident X/Ypolarized EM waves to cross-polarized waves in a portion of Kaband spectrum and to obtain circularly polarized (CP) waves with broadband characteristics in the Ku and K band frequency spectrum. The unit cell comprises of a symmetrical I-shaped metallic resonator with a single rectangular split ring resonator at the centre. The rotation of the induced surface currents on the meta-structure and the phase profile of the reflected waves confirms the presence of left-handed CP waves. When rotated in XY plane around Z-axis by 90°, this meta-atom reflects cross polarized waves with 180° phase difference compared to the original meta-atom across the entire operational bandwidth. This phase profile is utilized to realize a checkerboard metasurface and it is observed that significant RCS reduction is achieved in the cross-polarization conversion band. The overall size of the optimized unit cell is 0.26 × 0.26 × 0.07 λo3 mm3 and reflects CP waves with an axial ratio (AR) less than 3 dB from 15.3 GHz to 26.03 GHz. At the same time, cross-polarization conversion is observed from 28.33 GHz to 35.4 GHz, which makes the design best suitable for future wireless communication and RCS reduction application 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.