Faculty Publications
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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 High-Gain Half-Bow-Tie Antenna with Tapered Slots for Foliage Penetration Radar Application(Institute of Electrical and Electronics Engineers Inc., 2024) Shetty, A.K.; Goud, M.G.; Kandasamy, K.; Srihari, P.; Pardhasaradhi, B.P.; Cenkarmaddi, L.R.In this study, a compact, low-profile, high-gain half-bow-tie antenna with tapered slots is designed specifically for foliage penetration radar (FOPEN) applications. The proposed antenna design begins by vertically bisecting a conventional bow-tie antenna, followed by the addition of two vertical metal strips to enhance the operational bandwidth. To achieve effective impedance matching across the desired frequency range, two horizontal conductive strips and a central balun circuit are integrated into the design. To further optimize the antenna for integration into aerial platforms, the gain and radiation pattern are refined by incorporating two additional metal strips strategically placed on the right side of the bow-tie structure. These design modifications result in a compact antenna with dimensions of 0.43λx 0.4λ x 0.005λ where λ is the wavelength corresponding to the lower frequency of operation. The optimized antenna achieves a realized gain of 6.5 dBi and an impedance bandwidth of 110 MHz, making it highly suitable for FOPEN applications. The enhanced gain, achieved with a single dielectric layer, demonstrates the potential of this design for efficient foliage penetration radar systems. © 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 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