scispace - formally typeset
Search or ask a question
Author

M. V. Kartikeyan

Bio: M. V. Kartikeyan is an academic researcher from Indian Institute of Technology Roorkee. The author has contributed to research in topics: Gyrotron & Antenna (radio). The author has an hindex of 19, co-authored 247 publications receiving 1944 citations. Previous affiliations of M. V. Kartikeyan include European Atomic Energy Community & Indian Institutes of Technology.


Papers
More filters
Book
17 Nov 2003
TL;DR: In this article, basic principles and gyrotron cavities are discussed and a detailed calculation of RF behavior behavior behavior is presented, along with practical considerations for Gyrotron design.
Abstract: 1 Introduction.- 3 Basic Principles and Gyrotron Cavities.- 4 Calculation of RF Behaviour.- 5 Practical Considerations for Gyrotron Design.- 6 Electron Optical and Guiding System.- 7 Output Taper and Quasi-optical Launcher.- 8 RF Window.- 9 Examples.- 10 Applications.- References.

275 citations

Journal ArticleDOI
01 Jun 2010-Frequenz
TL;DR: In this paper, the effect of DGS to the different antenna parameter enhancement is studied, where the authors show that the value of the inductance and capacitance depends on the area and size of the defect.
Abstract: Defected ground structures (DGS) have been developed to improve characteristics of many microwave devices. Although the DGS has advantages in the area of themicrowave filter design, microwave oscillators, microwave couplers to increase the coupling, microwave amplifiers, etc., it is also used in the microstrip antenna design for different applications such as antenna size reduction, cross polarization reduction,mutual coupling reduction in antenna arrays, harmonic suppression etc., TheDGS ismotivated by a study of Photonic/Electromagnetic Band gap structures. The etching of one or more PBG element creates defect in the ground plane and used for the same purpose. The DGS is easy to be an equivalent L-C resonator circuit. The value of the inductance and capacitance depends on the area and size of the defect. By varying the various dimensions of the defect, the desired resonance frequency can be achieved. In this paper the effect of DGS, to the different antenna parameter enhancement is studied. Index Terms – Defected Ground Structure, Microstrip Antennas.

130 citations

Journal ArticleDOI
TL;DR: An extensive thorough investigation of diversity and mutual coupling (correlation) reduction techniques in compact MIMO antennas is carried out.
Abstract: Multiple input multiple output (MIMO) antenna is at core of the presently available wireless technologies. The design of MIMO antennas over a limited space requires various approaches of mutual coupling reduction, otherwise gain, efficiency, diversity gain, and radiation patterns will be severely affected. Various techniques have been reported in literature to control this degrading factor and to improve the performance of the MIMO antennas. In this review paper, we have carried out an extensive thorough investigation of diversity and mutual coupling (correlation) reduction techniques in compact MIMO antennas.

110 citations

Journal ArticleDOI
TL;DR: In this paper, the influence of misalignment of the insert on gyrotron operation has been investigated and the feasibility of manufacturing a 2MW continuous-wave coaxial cavity gyroron at 170 GHz has been demonstrated.
Abstract: The basic investigations on a coaxial cavity gyrotron operating at 165 GHz have been accomplished and the feasibility of manufacturing a 2-MW continuous-wave coaxial cavity gyrotron at 170 GHz has been demonstrated. In the last measurements, the data required for fabrication of an industrial tube have been completed. The influence of misalignment of the insert on gyrotron operation has been investigated. The limitation of the high-voltage performance of the electron gun due to buildup of a Penning discharge has been suppressed and the leakage current to the insert has been measured as a function of the retarding collector voltage.

77 citations

Journal ArticleDOI
TL;DR: In this paper, a 2 × 2 circularly polarized (CP) antenna is proposed to resonate at 5.8 GHz IEEE 802.11 WLAN band for non-line of sight (NLOS) communication.
Abstract: A 2 × 2 circularly polarized (CP) MIMO antenna is proposed to resonate at 5.8 GHz IEEE 802.11 WLAN band for non-line of sight (NLOS) communication. The proposed design achieves circular polarization with two optimized 90◦ apart rectangular slots etched at the center of a truncated rectangular patch. The proposed MIMO covers 5.49–6.024 GHz frequency band. The achieved isolation between two ports is more than 33 dB. The gain at the 5.8 GHz resonant frequency is 5.34 dBi. The diversity performance in terms of gain, ECC, and MEG has been reported.

77 citations


Cited by
More filters
Journal ArticleDOI

[...]

08 Dec 2001-BMJ
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

33,785 citations

Journal ArticleDOI
TL;DR: In this paper, the capabilities for vacuum electronic device (VED) sources of powerful terahertz (THz) and near-THz coherent radiation, both CW or average and pulsed, were evaluated.
Abstract: Recent research and development has been incredibly successful at advancing the capabilities for vacuum electronic device (VED) sources of powerful terahertz (THz) and near-THz coherent radiation, both CW or average and pulsed. Currently, the VED source portfolio covers over 12 orders of magnitude in power (mW-to-GW) and two orders of magnitude in frequency (from ; 10 THz). Further advances are still possible and anticipated. They will be enabled by improved understanding of fundamental beam-wave interactions, electromagnetic mode competition and mode control, along with research and development of new materials, fabrication methods, cathodes, electron beam alignment and focusing, magnet technologies, THz metrology and advanced, broadband output radiation coupling techniques.

860 citations

Journal ArticleDOI
TL;DR: This review focuses on recent developments in the field of DNP with a special emphasis on work done at high magnetic fields (> or =5 T), the regime where contemporary NMR experiments are performed.
Abstract: Dynamic nuclear polarization (DNP) is a method that permits NMR signal intensities of solids and liquids to be enhanced significantly, and is therefore potentially an important tool in structural and mechanistic studies of biologically relevant molecules. During a DNP experiment, the large polarization of an exogeneous or endogeneous unpaired electron is transferred to the nuclei of interest (I) by microwave (microw) irradiation of the sample. The maximum theoretical enhancement achievable is given by the gyromagnetic ratios (gamma(e)gamma(l)), being approximately 660 for protons. In the early 1950s, the DNP phenomenon was demonstrated experimentally, and intensively investigated in the following four decades, primarily at low magnetic fields. This review focuses on recent developments in the field of DNP with a special emphasis on work done at high magnetic fields (> or =5 T), the regime where contemporary NMR experiments are performed. After a brief historical survey, we present a review of the classical continuous wave (cw) DNP mechanisms-the Overhauser effect, the solid effect, the cross effect, and thermal mixing. A special section is devoted to the theory of coherent polarization transfer mechanisms, since they are potentially more efficient at high fields than classical polarization schemes. The implementation of DNP at high magnetic fields has required the development and improvement of new and existing instrumentation. Therefore, we also review some recent developments in microw and probe technology, followed by an overview of DNP applications in biological solids and liquids. Finally, we outline some possible areas for future developments.

777 citations