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Now showing items 1 - 16 of 25779

  • Tailoring the spectral response of a dogbone doublet metamaterial

    Sarin, V. P.   Pradeep, Anju   Jayakrishnan, M. P.   Chandroth, Aanandan   Mohanan, P.   Kesavath, Vasudevan  

    The detailed experimental and simulation studies of the stacked dogbone metamaterial particles are presented in this article. Besides the conventional left handed propagation mode, it is observed that the structure supports Fabry-Perot resonant modes and the excitation of this mode can be identified from the right handed resonant tunnel band in the dispersion diagrams. It is shown that the coupling between the Fabry-Perot and left handed resonant modes gives flat tunnel band characteristics in the dispersion diagram and is associated with huge electromagnetic absorption. The spectral response can be tailored by varying the stacking thickness of the sample making it suitable for microwave absorption and left handed transmission applications. (c) 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1347-1353, 2016
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  • Extraordinary transmission technique for microwave antenna applications

    Sarin, V. P.   Jayakrishnan, M. P.   Aanandan, C. K.   Mohanan, P.   Vasudevan, K.  

    The extraordinary optical transmission (EOT) through an array of holes in a metal plate has been a constant source of inspiration for researchers for over a decade (Ebbesen et al 1998 Nature 391 667-9). In this paper, an EOT analogue is proposed in the microwave frequency range for enhancing the radiation performance of a stacked dipole antenna. It is observed that the back radiated power of the antenna is considerably reduced and the reason behind transmission enhancement is the excitation of Fabry-Perot resonant modes on the slit loaded aperture. Computational analysis based on finite difference time domain is performed for identifying the true reason behind resonant transmission enhancement.
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  • Tailoring the spectral response of a dogbone doublet metamaterial

    Sarin, V. P.   Pradeep, Anju   Jayakrishnan, M. P.   Chandroth, Aanandan   Mohanan, P.   Kesavath, Vasudevan  

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  • An experimental realization of cylindrical cloaking using dogbone metamaterials

    Sarin, V. P.   Jayakrishnan, M. P.   Vinesh, P. V.   Aanandan, C. K.   Mohanan, P.   Vasudevan, K.  

    The quest for invisibility has inspired a deep ardour in the research community over the past decade. The invention of metamaterials has boosted the research on electromagnetic cloaking due to its unusual electromagnetic parameters under plane wave incidence. In this study, we propose a novel cloaking scheme, using dogbone metamaterials, for effectively routing the incident electromagnetic fields around a target metal cylinder under consideration. Notable reduction in the scattered power is observed from the target in comparison to an uncloaked target. Experiments and simulations validate an effective reduction in the scattering cross section of the target and effective guiding of the incident plane wave around the target.
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  • A Broadband L-Strip Fed Printed Microstrip Antenna

    Sarin, V. P.   Nishamol, M. S.   Tony, D.   Aanandan, C. K.   Mohanan, P.   Vasudevan, K.  

    A broadband L-strip fed printed microstrip antenna is presented. The strip loaded slotted broadband microstrip antenna is fed by an L-strip feed line to achieve impedance matching for the higher order modes of the patch antenna in addition to the existing resonances. The antenna offers 74% bandwidth when printed on a substrate of dielectric constant 4.2 and has an overall dimension of 42 X 55 X 3.2mm(3). The simulated and experimental reflection characteristics of the antenna with and without the L-feed along with radiation patterns, input impedance variations, gain and efficiency of the final antenna are presented and discussed. The time domain transient analysis indicates a minimum dispersion to the transmitted pulse.
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  • Wideband Printed Microstrip Antenna for Wireless Communications

    Sarin, V. P.   Nassar, Nisha   Deepu, V.   Aanandan, C. K.   Mohanan, P.   Vasudevan, Kesavath  

    A simple electromagnetically coupled wideband printed microstrip antenna having a 2: 1 VSWR bandwidth of 38% covering the 5.2/5.8-GHz WLAN, HIPERLAN2, and HiSWANa communication bands is presented. The large bandwidth is obtained by adding a rectangular metal strip on a slotted square microstrip antenna. The antenna occupies an overall dimension of 42 x 55 x 3.2 mm(3) when printed on a substrate of dielectric constant 4. It exhibits good radiation characteristics and moderate gain in the entire operating band. Details of the design along with experimental and simulation results are presented and discussed.
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  • Broadband non-resonant split ring resonator-based artificial high dielectric substrate

    Anila, P., V   Sarin, V. P.   Manoj, M.   Remsha, M.   Mohanan, P.  

    This paper presents a technique of using magnetic metamaterial as a broadband non-resonant artificial high dielectric substrate for achieving enhanced radiation performance in the microwave region. The selected metamaterial (MTM) is the basic single split-ring resonator (SRR) printed on a bare dielectric substrate of permittivity 3.8. When it is electrically excited by a plane wave, a high permittivity of 25 for the frequency range of 0.5-3.1 GHz is achieved. The application of the artificially made high dielectric substrate is validated with a 1.3 dBi gain enhancement of a broadband slot antenna with a single finite transmitter array of 5 x 4 high dielectric metamaterial substrate. The MTM-antenna composite is having an overall size of 60 x 48 x 21.6 mm(3) when printed on a substrate of dielectric constant 3.8 and height 1.6 mm. The detailed study of MTM unit cell and the effect of MTM on antenna performance is thoroughly studied in simulation and validated with free space measurements. (C) 2020 Elsevier GmbH. All rights reserved.
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  • Varactor Controlled Frequency and Polarization Reconfigurable Microstrip Antenna

    Nishamol, M. S.   Sarin, V. P.   Tony, D.   Anandan, C. K.   Mohanan, P.   Vasudevan, K.  

    A single feed compact microstrip antenna achieving frequency and polarization diversity using a varactor is presented. A simple patch antenna with an X-slot constitutes the fundamental structure. The frequency and polarization agility is realized by varying the reactance of an embedded varactor at the center of the X-slot with respect to the biasing from 0 to 25 V. The prototype fabricated on a substrate of dielectric constant (epsilon(r)) 4.4 and height (h) 1.6 mm is fed by a proximity feed fabricated using the same substrate. By controlling the bias voltage of the varactor, the polarization of the antenna can be switched between linear and circular polarization. Furthermore, the proposed antenna offers stable broadside radiation characteristics without any extra impedance matching circuit. The frequency and polarization diversities of this design could potentially improve the reliability of wireless communication systems. The details of the antenna are presented and discussed. (C) 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE 21:680-686, 2011.
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  • COMPACT DUAL FREQUENCY DUAL POLARIZED CROSS PATCH ANTENNA WITH AN X-SLOT

    Nisha, M. S.   Sarin, V. P.   Gijo, Augustin   Deepu, V.   Anandan, C. K.   Mohanan, P.   Vasudevan, Kesavath  

    A new design of a compact single-feed dual frequency dual polarized microstrip antenna with an X-slot is presented. The proposed antenna generates two orthogonally polarized radiations with center frequencies at 1.42 GHz and 1.79 GHz, respectively. . For fixed dual frequency operation, the antenna has an area reduction of 74% and 59% for the respective frequencies compared to standard rectangular patches. The antenna exhibits broadside radiation pattern and has sufficient gain for the two hands. (c) 2008 Wiley Periodicals. Inc. Microwave Opt Technol Lett 50: 3198-3201 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23903
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  • DESIGN OF A CIRCULARLY POLARIZED RECTANGULAR MICROSTRIP ANTENNA FOR GPS APPLICATIONS

    Nishamol, M. S.   Sarin, V. P.   Tony, D.   Aanandan, C. K.   Mohanan, P.   Vasudevan, Kesavath  

    A compact design of a single feed microstrip antenna for circular polarization (CP) is proposed and studied. CP is brought about by embedding a slot in a cross shaped patch. The structure. enables an area reduction of 46% as compared to conventional rectangular microstrip antenna. The antenna offers a 2:1 VSWR bandwidth from 1.53 to 1.61 GHz on a substrate of dielectric constant 4.4 and height 1.6 mm with a broadside radiation characteristic in the entire band. The 3 dB axial ratio bandwidth of the antenna is 5% with moderate gain that covers global positioning system (GPS) L1 band. Simulation and experimental results of the antenna are presented and discussed. (C) 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:468-470, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25706
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  • Toroidal dipole-induced coherent forward scattering from a miniaturized cloaking structure

    Sarin, V. P.   Vinesh, P. V.   Manoj, M.   Aanandan, C. K.   Mohanan, P.   Vasudevan, K.  

    The physical existence of microwave toroidal dipole in a dogbone metallic inclusion-based miniaturized cloaking structure is verified in this paper. The excitation of toroidal dipole moments on the studied composite is verified using multipole scattering formalism. The presence of the toroidal Fano resonance significantly enhances resonant forward scattering from the structure for normal incidence. Multipolar contribution from the electric, magnetic and toroidal moments significantly enhances the scattering cross-section of the composite as compared to a bare cylindrical metallic object. Applicability of the proposed scheme is tested inside an anechoic chamber using reflection measurements on the fabricated structure and is subsequently validated in computer simulations in the microwave frequency regime.
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  • Experimental realization of electromagnetic toroidal excitation for microwave applications

    Sarin, V. P.   Vinesh, P. V.   Manoj, Mani   Chandroth, Aanandan   Pezholil, Mohanan   Kesavath, Vasudevan  

    An experimental realization of resonant toroidal dipole excitation in the microwave regime is presented in this paper. The metasurface proposed herewith is an asymmetric double split-ring resonator exhibiting Fano-like resonance profile. One could observe that cascading the metasurface results in near-field transverse and longitudinal coupling creating dual-band toroidal moments on the structure. This planar scheme will simulate the development of enhanced light-matter interaction, electromagnetic wave slowdown and sensor design. Here we report the experimental realization of the phenomenon in the S-band frequencies, and the results are verified using multipole scattering analysis.
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  • A Wideband Stacked Offset Microstrip Antenna With Improved Gain and Low Cross Polarization

    Sarin, V. P.   Nishamol, M. S.   Tony, D.   Aanandan, C. K.   Mohanan, P.   Vasudevan, K.  

    A broadband printed microstrip antenna having cross polarization level > 15 dB with improved gain in the entire frequency band is presented. Principle of stacking is implemented on a strip loaded slotted broadband patch antenna for enhancing the gain without affecting the broadband impedance matching characteristics and offsetting the position of the upper patch excites a lower resonance which enhances the bandwidth further. The antenna has a dimension of 42 x 55 x 4.8 mm(3) when printed on a substrate of dielectric constant 4.2 and has a 2: 1 VSWR bandwidth of 34.9%. The antenna exhibits a peak gain of 8.07 dBi and a good front to back ratio better than 12 dB is observed throughout the entire operating band. Simulated and experimental reflection characteristics of the antenna with and without stacking along with offset variation studies, radiation patterns and gain of the final antenna are presented.
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  • An electromagnetically coupled dual-band dual-polarized microstrip antenna for WLAN applications

    Sarin, V. P.   Nishamol, M. S.   Augustin, Gijo   Mohanan, P.   Aanandan, C. K.   Vasudevan, K.  

    A new design of a dual-band dual-polarized electromagnetically coupled slot loaded square patch antenna, covering the WLAN 5.2 GHz curd 5.8 GHz hands, achieving bandwidth enhancement by using tapered slot structure, is presented here. The proposed antenna covers 5.09-5.47 GHz and 5.7-5.88 GHz bands. Details of the antenna design along with experimental and simulated results are presented and discussed. (c) 2008 Wiley Periodicals, Inc.
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  • An Electronically Reconfigurable Microstrip Antenna With Switchable Slots for Polarization Diversity

    Nishamol, M. S.   Sarin, V. P.   Tony, D.   Aanandan, C. K.   Mohanan, P.   Vasudevan, K.  

    An electronically reconfigurable microstrip antenna with circular and linear polarization switching is presented. The prototype fabricated on a substrate of dielectric constant (epsilon(r)) 4.4 and height (h) 1.6 mm is fed by a proximity feed fabricated using the same substrate. By controlling the bias voltage of two PIN diodes, the polarization of the antenna can be switched between three states; two states for linear polarization (horizontal and vertical) and one state for circular polarization (RHCP). Simulation and experimental results show that the proposed antenna has a cross polar level better than 10 dB in the linear polarization state and 18 MHz axial ratio bandwidth in the circular polarization state. The frequency and polarization diversities of this design could potentially improve the reliability of wireless communication systems.
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  • Sarin, V. P.   Nishamol, M. S.   Tony, D.   Aanandan, C. K.   Mohanan, P.   Vasudevan, K.  

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