Institute of Radio Physics and Electronics
Total Sanctioned grant (for 3 years) – Rs. 25.01 lakhs
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- Bu səhifədəki naviqasiya:
- Total sanctioned grant (for 3 years) – Rs. 19.27 lakhs
- Electronics
Total Sanctioned grant (for 3 years) – Rs. 25.01 lakhs
Principal Investigator – Dr. A. Maitra, Institute of Radio Physics and ElectronicsTotal sanctioned grant (for 3 years) – Rs. 19.27 lakhs
Principal Investigator – Professor S.S. De, Institute of Radio Physics and ElectronicsTotal sanctioned grant (for 3 years) – Rs. 14.48 lakhs
Principal Investigator – Professor A. DasGupta, Institute of Radio Physics and Electronics Total sanctioned grant (for 3 years) – Rs. 14.06 lakhs The present research activities of the Center cover different altitude regions of the Earth’s space environment from the lower atmosphere to the Sun. ANNEXURE – V(A) RESEARCH ACTIVITIES (EXECUTED) Solid State Electronics & Circuits (inclding VLSI & Nanoelectronics) Transport in C-Nanotube The Boltzmann transport equation is applied to study the transport limited by acoustic phonon in Carbon nanotube. Formulation for optical phonons is being conducted. Thermal Processes in Semiconductors Some works are carried out to formulate heat generation and distribution processes in semi-conducting materials used in optoelectronics devices. The radiative heat transfer between a point like dipole and a surface has been evaluated using fluctuation-dissipation theorem. The result may be useful in nanostructure design. Nanscale MOSFET With downscaling of device dimensions, Double Gate (DG) MOSFETs have drawn considerable attention for their potential to beter control short channel effects. A comprehensive and physically based investigaton has been carried out to deermine the threshold voltage Vt and subthreshold slope S of a fully depleted DG MOSFET taking into account quantum mechanical effects and the bandgap narrowing due to heavy channel doping. The values of Vt and S have also been determined by using a 2D numerical simulator ATLAS. Good agreement between analytical results and simulated values is obtained validating the theory. Si Photonics Some investigations have been made on (i) effect of Ge-content on the Performance of Si/SiGe photodetector; (ii) Use of Fuzzy Logic in Semiconductor Device Modeling and (iii) Resonant cavity-enhanced Ge Schottky photodetector. Also work has been continuing on (i) Si/SiGe Multiple Quantum Well (MQW) photodetector (PD) structure, (ii) some optical properties of Quantum Dot (QD) structure, (iii) Performance analysis of Quantum Dot Infra-red Photodetector (QDIP) structures. Incorporation of C in SiGe alloy reduces the strain in the alloy/Si heterojunction. An estimation of the composition in Si1-x-yGexCy alloy to be used as a photodetector material exhibiting lage absorption coefficient has been made. A formulation of fundamental absorption coefficient of Si1-xGex due to alloy disorder has ben completed.
Calculations have also been made for the electron transition rates in GaAs/GaAlAs superlattices mediated by polar longitudinal optic phonons. The intersubband and capture rates are calculated and their variations with well widths have been studied. The work has been published in (CODEC – 06). Microwave and Lightwave Technology Dielectric Resonator Antennas Cultivated during last two decades, DRA is now quite a matured field of investigation and its resonant modes are well examined. In our recent works we have explored the conventional known modes in composite DRA geometries to use them in an unconventional way. The new composite DRA geometries investigated include four-element cylindrical DRA and two-element half-hemispherical DRAs and wideband compact monopole-type DRAs are proposed in IEEE AP Transactions. In another set of investigation, we have designed two shaped cylindrical DRAs respectively for achieving a broadband high gain circularly polarized as well as a very wideband linearly polarized wireless antenna to operate covering four commercial wireless bands. These are published/reported in Electronics Letters and IEEE IEEE AP Transactions. An ultra wideband DRA-monopole antenna with 3:1 operating bandwidth has been theoretically and experimentally examined. The physical insight in to its wideband operation has been thoroughly studied with view to develop a comprehensive design guideline and is reported in IEEE AWPL, 2006. Microstrip Antenna Several aspects of microstrip radiator have been investigated during this period. One of them is microstrip patch loaded with a pair of balanced shorted pins. This unlike previous investigation helps in improving input impedance performance. New ring shaped defected ground structure (DGS) has been studied for both circuit and antenna applications. In this investigation, we have shown for the first time that a simple defect can suppress the mutual coupling between a pair of circular patches in an array environment and that can be of the order of 5 to 7 dB. Compact microstrip antenna having a cavity-shaped ground plane has been theoretically and experimentally examined. New CAD has also been proposed to provide easy design parameters. All this studies are important from application point of view and are results are now available in IEEE AWPL, 2006 issue. Travelling Wave Semiconductor Optical Amplifier Semiconductor Optical Amplifiers (SOAs) are increasingly being used in present day fibre optic communication and networking systems. Apart from amplification of light signals, SOAs are attractive in making all optical network elements like routers, wavelength converters, and cross connects. For accurate prediction of performance of SOAs, suitable mathematical or circuit models are needed to design the SOAs and to predict their operational characteristics We present an equivalent lumped-element electric circuit model that is utilized by SPICE for the design and analysis of traveling wave (TW) semiconductor laser amplifier. The circuit elements are derived from the rate equations involving carrier and photon densities. Results based on SPICE simulation agree well with experimental data as well as with values obtained from sophisticated analysis. It is easy to include parasitics to the intrinsic circuit model to examine the performance of the amplifiers, like modulation bandwidth or transient response. Optical Communication Calculations have been made for incoherent in-band crosstalk induced power penalty in amplified Wavelength Division Multiplexed Networks. In this work we present an analysis of interferometric in-band crosstalk introduced by a number of sources in a multi-channel wavelength division multiplexed network. Our theory differs from the earlier ones in two aspects. First it takes into account dominant signal-amplified spontaneous emission (ASE) beat noise in optical amplifiers connected to crosstalk sources. Secondly, whereas the earlier theories use Gaussian probability distribution function (PDF) for noise, we use chi-squared distribution (CSD). We have derived analytical expression for power penalty from the formula for bit error rate by employing saddle point approximation (SPA) to the chi-squared pdf. We also calculate power penalty using Gaussian PDF for crosstalk noise for finite extinction ratio using average and optimized detection thresholds. The crosstalk induced penalty, calculated with CSD-SPA for a single interfering channel matches closely with the available experimental results without amplification and with amplification. When the number of interfering sources is small CSD-SPA may be used to accurately calculate crosstalk power penalty, but for larger number of sources ( ≥ 4) Gaussian PDF with average detection threshold may be used as verified from the available experimental results. Cross-talk issues in Wavelength Division Multiplexing (WDM) systems have been addressed. HEMT Photoreceiver Modelling The photoreceivers in fibre optic communication are made of MSM photodetectors and low noise preamplifiers in transimpedance feedback configuration. We have optimized the transimpedance bandwidth product of a MSM PD – HEMT amplifiers based on a delta doped AlInAs-GaInAs taking into account radio frequency modeling in a SPICE framework The simulation value of h-parameter show god agreement with experimental data. The optimized values of fT and fmax are derived by changing the width of the with W and doping in the HEMT. Optical heterodyning Novel schemes have been developed for generation of ultra-stable ( i.e having very low phase noise ) microwave and millimeter-wave signal using heterodyning of laser signal in broad-band photo-detectors. The schemes are also capable of generating terahertz signal (which is not possible with electrical means). Optically generated microwave/millimeter-wave signals are useful in many applications like broad-band wireless access, software defined radio, antenna remoting etc. The work has resulted in a paper useful for mobile communication application to be presented in PIERS ’07 International conference in China. Microwave Sources A novel microwave resonant-cap structure useful for microwave IMPATT/Gunn oscillator and power combiner has been analyzed from fundamental electromagnetic concept and interesting results have been obtained regarding design of efficient oscillators and power combiners. The theoretical results will be compared with experimental characterization by measuring the driving point impedance of the structures when mounted with suitable jigs. Photodetectors Some investigations have ben made on (i) effect of Ge-content on the Performance of Si/SiGe photodetector; (ii) Use of Fuzzy Logic in Semiconductor Device Modeling and (iii) Resonant cavity-enhanced Ge Schottky photodetector. Also has been working on (i) Si/SiGe Multiple Quantum Well (MQW) photodetector (PD) structure, (ii) some optical properties of Quantum Dot (QD) structure, (iii) Performance analysis of Quantum Dot Infra-red Photodetector (QDIP) structures Microwave Tomography Two new algorithms for microwave imaging have been developed to reconstruct the image from the synthetic data contaminated with white Gassian noise. The results are encouraging. Another algorithm, based on Conjugate Gradient Method, is being developed. Space and Atmospheric Science and Technology Lower Atmosphere and Pollution During the period under review attempts have been and are being made to measure methane emission rate from rice fields, uplands and also from ecosystems infected by water hyacinth and other aquatic plants. In addition, monitoring of the levels of concentrations of surface ozone, CO, NOx, NMHC, total olumnar ozone, aerosol optical depth, water column density, intensity of 305 nm is being continued. Moreover, attempts have been made to estimate the concentration of highly reactive hydroxyl radical at the surface level employing the knowledge of the measured value of the mixing ratio of CO, NO, NO2 and the necessary reaction rates. Satellite, & GPS GAGAN (GPS and Geo Augmented Navigation) TEC (Total Electron Content) data have been analyzed prior to strong earthquakes to find any ionospheric precursor to the quake. The ionospheric response after the seismic shock has also been examined for December 26, 2004 Andaman-Sumatra earthquake and October 08, 2005 Pakistan earthquake using these TEC data.
gamma parameters in relation to rain is a good indicator of the types of rain whereas that of lognormal distribution is not. The models of DSD in terms of gamma and lognormal distributions are obtained for the measuremenst at Kolkata. Rain parameters studies TRMM satellite data The TRMM (Tropical Rain Measurement Mission) satellite data have been used to obtain some of the features of rain over Kolkata. The Precipitation Radar (PR) data of Tropical rainfall Measuring Mission (TRMM) which provide information on height profiles of radar reflectivity (Z), rain rate (R), rain (storm) height and rain type, have been utilized. The relationship between the surface rain rate and rain height indicates that the rain rate has a distinct control of the rain height that depend on the rain rate and season. Also, rain rate varies with height indicating that the surface rain rate needs correction to get the effective rain rate over the earth-space path which can be used to predict the rain attenuation from surface based rainfall measurements. The Z-R relationship revealed from the TRMM data has been compared to that obtained from the ground-based disdrometer observations at Kolkata, which usually show a good correspondence for stratiform rain, indicating that the TRMM rain data should be fairly accurate in estimating the rain rate over Kolkata. Potential Gradient of the Atmosphere The recorded data of atmospheric potential gradient over Kolkata and Tripura University sites have been statistically analyzed. Their variations are studied and interpreted for the observational periods. On-going recordings are being continued. VLF Sferics The recording of VLF Sferics is being continued over Kolkata and Tripura University sites with similar set-up. The data of transmitted VLF signal VTX1 from Kolkata at 16.3 KHz from one of the Indian Navy Station at Vijayanarayanam (8025’ 59.88” N, 77048’ E) are analysed. Diurnal variations of VLF sferics are critically examined over Kolkata. Meteor and Solar flare effects on VLF sferics have been detected. Some analyses of the collected data came out in research publications. During the period of earthquake on 8th October, 2005, at the India-Pakistan border, some remarkable spiky variations in the record are found over Agartala at 6 KHz and 9 KHz frequencies. From October 3, 2005, to October 13, 2005, these spikes with different duration and magnitudes have been recorded at these frequencies. The observed spikes are analyzed and found to be due to precursors to the India-Pakistan border earthquake. From the data of vertical potential gradient and VLF sferics, correlation studies of VLF sferics with atmospheric vertical electric field at Kolkata along with its deviation from global character have been carried out. From the recording of the transmitted VLF signals, we observed Meteor showers through its effects on VLF transmission. Some collaborative works by lodging campaign with Equatorial Geophysical Research Laboratory (EGRL) at Tirunelveli, Tamilnadu, under Indian Institute of Geomagnetism, measurements of vertical potential gradient of the atmosphere, air-earth current and conductivity of the atmosphere by Gardien condenser are taken from Tripura University site. Schumann Resonance Spectra Recording Further advancement in the fabrications of necessary instrumental setup to detect Schumann resonance spectra over Kolkata is being carried out. A signal processor consisting of a pre-amplifier and a main amplifier has been designed for the detection of Schumann resonance spectra. Some attempts are made to install a set of Loop antenna for their detection. Raindrop Size Distribution and Attenuation The variations of raindrop size distribution and other parameters have been investigated theoretically considering the influence of coalescence and evaporation processes. The rain attenuation in millimeter and sub-millimeter wave region using gamma raindrop size distribution is calculated. Some attempts are taken to compare it with experimental results. Characteristics of Lightning Discharges Further work is carried out on mode decomposition process to obtain the lightning discharge spectra of the first mode of the Earth-ionosphere waveguide in terms of some physical parameters. Seismo-Electromagnetic Effects during Earthquake The formation of quasi-periodic horizontal inhomogeneities in the ionospheric conductivity produced due to the enhancement of DC electric field during seismic related phenomena introduced changes in the lower atmospheric parameters. A model calculation has been made for the lower ionospheric region to determine the variation of electron temperature and electron density during enhanced precursory electromagnetic field produced in the earthquake region. Electric Field due to Cloud Charge Distribution Using quasi-hydrodynamic formulation, some model calculations about the thundercloud electric field are carried out, the results of which may be used to study the nature of variation of field in the atmosphere during lightning. Plasma Theoretical investigations on non-linear heating of the ionospheric plasma during HP/HF propagation are being continued. Numerical estimation is made to study the variation of electric field within the medium for a specific height range. Systems Science Image Processing In present work, arithmetic subtraction is performed using two images, the mask image of a region of patient’s body and the sample image of the same anatomical region as the mask, taken after a little bit later from the injection of a contrast medium into patent’s bloodstream. The net effect of subtracting the mask from the sample image is that the areas those are different between them, appears as the output image and is capable of displaying the enhanced details. Based on this approach, we have implemented the hardware architecture using SDA 85M microprocessor kit. Fuzzy Systems Identification of fuzzy model of a complex dynamic system concerning its structure as well as parameter is an important issue in many disciplines of engineering. In our work we have introduced various concepts of the development of a hierarchical self organized approach that evolves automatically the structure along with parameters of fuzzy membership functions from given set of pattern. The particle swarm optimization (PSO) technique has been employed as the learning tool after removing some of its inherent problems with convergence. Work in Non-Thrust Area The Centre is the first University department in the country to initiate teaching and research in electronis, communication, computers, ionosphere and space science. The Institute was established in 1949. Prior to that the seed for the new department germinated in the Wireless Lab and Wireless special paper in the Physics department. Cosidering the rich history and many pioneering work done in the Centre, a few teachers of the Centre has initiated research on the Development of Early History of Radio Science in India. Some results have been presented in INCURSI 07 conferences celebrating the Golden Jubilee of Radio Science in NPL. ANNEXURE – V(B) RESEARCH ACTIVITIES (PROPOSED) Solid State Electronics and Circuits Transport and scattering mechanisms Work in the area of ballistic transport in 2D and 1D systems will be undertaken to find out the transport parameters in such cases. The work on superlattices will also be extended to find the scattering limited mobilities for such systems. Si Photonics Work on Si based optoelectronic devices will be continued. In particular, the quantum efficiency of photodetectors using Si/SiGe Quantum Wells will be estimated. Recent results on Quantum Confined Stark Effect in Si/SiGe MQWs will be examined to predict the performance as modulators and detectors. The Raman gain and two photon absorption in Si and its alloys will be investigated. MOS Devices Further work on nanoscale MOS will be continued using simulation tools and developing analytical models. Optoelectronics: Quantum Cascade Lasers Work that has already been continuing (MQW SiGe PD, Optical properties of QD, QDIP and WDM systems) to be advanced and completed. Fuzzy Logic based modeling of semiconductor photonic devices will be carried out. Microwave and Lightwave Technology Dielectric Resonator Antenna We have planned to pursue further investigations on the applications of defective ground structures (DGS) on DRAs and microstrip antennas. The studies will be focused on reduction of mutual coupling between antenna elements in array configurations. Investigations have just started with electromagnetic metamaterials. Some new geometries with negative permeability are explored. We, therefore, intend to develop efficient theoretical model to estimate their magnetic and resonant characteristics. Experimental studies with metamaterial cells are also included in our agenda for the next phase. Optical Communication Presently a time domain reservoir model of SOA is being developed. There are plans to validate the model by using experimental results. With this model it is possible to characterize the transient behaviour of SOA which gains importance recently because of growing interest in all optical signal processing application. Investigations are also been carried out to use SOA in the PON network. Optical Heterodyning & Microwave Sources Research works already conucted in the above areas will be extended to realize their experiential proto types. Photodetectors Work that has already been continuing (MQW SiGe PD, Optical properties of QD, QDIP and WDM systems) is to be advanced and completed. Fuzzy Logic based modeling of semiconductor photonic devices will be carried out. Microwave Tomography Work on the development of the lgorithm, based on Conjugate Gradient Method, will be continued. Space and Environment Science and Technology Ionospheric Scintillation Work will be continued in the following areas:
Propagation Studies over Earth-Space and Terrestrial Paths The propagation over the earth-space path at Ku, K and Ka bands will be continued using a variety of techniques such as, receiving satellite signal, Doppler radar data and satellite data. The propagation study over an earth-space path is particularly important in view of proposed launch of the Indian satellite GSAT-4 will transmit Ka band beacon signals for propagation experiments in the Indian region. A national programme has been initiated by Satellite Application Centre, Ahmedabad in which the present group will participate with the experimental observations made at Kolkata. Megha Tropiques Mission of ISRO Yüklə 0,59 Mb. Dostları ilə paylaş:
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