Now showing items 1-20 of 65
Next Page| Abstract: | The MgAl2O4 ceramics were prepared by the conventional solid-state ceramic route and the dielectric properties studied in the microwave frequency region (3–13 GHz). The phase purity and crystal structure were identified using the X-ray diffraction technique. The MgAl2O4 spinel ceramics show interesting microwave dielectric properties (εr = 8.75, Qux f = 68 900 GHz (loss tangent = 0.00017 at 12.3 GHz), τf =−75 ppm/◦C). The MgAl2O4 has high negative τf, which precludes its immediate use in practical applications. Hence the microwave dielectric properties of MgAl2O4 spinels were tailored by adding different mole fractions of TiO2. The εr and Q factor of the mixed phases were increased with the molar addition of TiO2 into the spinel to form mixtures based on (1−x)MgAl2O4-xTiO2 (x = 0.0−1.0). For x = 0.25 in (1−x)MgAl2O4-xTiO2, the microwave quality factor reaches a maximum value of Qux f = 105 400 GHz (loss tangent = 0.00007 at 7.5 GHz) where εr and τf are 11.035 and −12 ppm/◦C, respectively. The microwave dielectric properties of the newly developed 0.75MgAl2O4-0.25TiO2 dielectric is superior to several commercially available low loss dielectric substrates. |
| URI: | http://dyuthi.cusat.ac.in/purl/519 |
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| APA3282.pdf | (689.8Kb) |
| Abstract: | A dual-port dual-polarized compact microstrip antenna for avoiding cross coupling between the two frequency bands is proposed and analyzed. This antenna offers channel isolation better than 25 dB, and is more compact compared to a conventional rectangular patch. Analytical equations for calculating the resonant frequencies at both ports are also presented. The theoretical calculations are verified using experimental results |
| URI: | http://dyuthi.cusat.ac.in/purl/1393 |
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| Analysis and de ... act microstrip antenna.PDF | (1.268Mb) |
| Abstract: | A new compact micro strip antenna element is analyzed. The analysis can accurately predict the resonant frequency, input impedance, and radiation patterns. The predicted results are compared with experimental results and excellent agreement is observed . These antenna elements are more suitable in applications where limited antenna real estate is available |
| URI: | http://dyuthi.cusat.ac.in/purl/1362 |
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| Analysis of a New Compact Microstrip Antenna.PDF | (3.188Mb) |
| Abstract: | Design equations are presented for calculating the resonance frequencies for a compact dual frequency arrow-shaped microstrip antenna. This provides a fast and simple way to predict the resonant frequencies of the antenna. The antenna is also analyzed using the IE3D simulation package. The theoretical predictions are found to be very close to the IE3D results and thus establish the validity of the design formulae |
| URI: | http://dyuthi.cusat.ac.in/purl/1381 |
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| Analytical Equa ... ncy Microstrip Antenna.PDF | (2.229Mb) |
| Abstract: | A modified H-plane sectoral horn antenna with identical E- and'H- plane.patterns over the X-band frequency is discussed. This system has significantly reduced side lobes and hack lobes. Half=power beam width and gain of the antenna are also improved with enhanced matching , Experimental results for a number of horns with various flanges are presented . These find practical application for illuminating symmetric antennas like paraboloids and polarization measurements in radio astronomy, etc. Compared to the fixed pyramidal horns. the present system offers great convenience in trimming the antenna characteristics |
| URI: | http://dyuthi.cusat.ac.in/purl/1433 |
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| Axially symmetr ... -plane sectoral horns.PDF | (1.253Mb) |
| Abstract: | A simple technique for obtaining identical E- and H-plane patterns from E-plane sectoral feed horn is presented. Halfpower beam width and gain of the antenna are also improved considerably. Experimental results for a number of horns with flanges of various parameters are also presented. This system may find practical application in radar and space communication systems |
| URI: | http://dyuthi.cusat.ac.in/purl/1431 |
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| Axially symmetr ... ne sectoral horn feeds.PDF | (1.818Mb) |
| Abstract: | Reduction of radar cross -section of dihedral corner reflectors using simulated corrugated surface (.SCS) is reported. This technique is found lo be more effective in the reduction of RCS or corner reflectors for normal incidence . A typical reduction of 40-50 dB is achieved using this method |
| URI: | http://dyuthi.cusat.ac.in/purl/1365 |
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| Backscattering ... rs using SCS technique.PDF | (1.362Mb) |
| Abstract: | The impedance bandwidth of a high permittivity cylindrical dielectric resonator antenna excited by a micro strip line was significantly improved by modifying the feed geometry. The 10 dB return loss bandwidth is enhanced from 12 to 26% without much affecting the gain and other radiation properties of the antenna. Good agreement has been observed between the predicted and measured results |
| URI: | http://dyuthi.cusat.ac.in/purl/1359 |
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| Broadband cylin ... dified microstrip line.PDF | (1.018Mb) |
| Abstract: | A new dual port microstrip antenna geometry for dual frequency operation is presented. The structure consists of the intersection of two circles of the same radius with their centres displaced by a small fraction of the wavelength . This antenna provides wide impedance bandwidth and excellent isolation between its ports. The gain of the antenna is comparable to that of a standard circular microstrip antenna operating at the same resonant frequency. A theoretical analysis for calculating the resonant frequencies of the two ports is also presented |
| URI: | http://dyuthi.cusat.ac.in/purl/1350 |
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| Broadband dual frequency microstrip antennas.PDF | (838.1Kb) |
| Broadband dual frequency microstrip antennas.PDF | (838.1Kb) |
| Abstract: | A microstrip antenna with large bandwidth is developed using a parasitic technique . Compared to the available wide-baud antennas,the proposed antenna structure is very compact and gives a lessdistorted radiation pattern with frequency . An impedance bandwidth,eight times that of a conventional patch antenna of the same size, Isachieved. The concept of coupled microstrip line model Is extended fortheoretical interpretation of the impedance loci |
| URI: | http://dyuthi.cusat.ac.in/purl/1360 |
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| Broad-Band Gap Coupled Microstrip Antenna.PDF | (2.586Mb) |
| Abstract: | A compact microstrip antenna with circular polarization radiation is demonstrated.A reducation in the required parameters for achieving CP radiation makes the present antenna design simpler |
| URI: | http://dyuthi.cusat.ac.in/purl/1373 |
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| Circularly pola ... act microstrip antenna.PDF | (1.230Mb) |
| Abstract: | Development of a new compact circular-sided microstrip antenna is presented. This antenna offers considerable area re- TABLE 2. Variation of Resonant Frequencies duction compared to standard rectangular microstrip antenna designed for the same frequency. Typical antenna design and experimental results for circular polarization are also demonstrated. 77je antenna has a 3-dB axial ratio bandwidth of 1.5% |
| URI: | http://dyuthi.cusat.ac.in/purl/1387 |
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| Compact circula ... circular polarization.PDF | (919.1Kb) |
| Abstract: | A compact single –feed multiband planar antenna configuration Suitable for GPS, DCS. 2.4/5.8 GHz WLAN applications are presented. The antenna has dimensions 38 x 3 x 1.6 mm and offers good radiation and reflection characteristics in the above frequency bands. The antenna has a simple geometry and can be easily fed using a 50 coaxial probe |
| URI: | http://dyuthi.cusat.ac.in/purl/1357 |
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| Compact planar ... GHz WLAN applications.PDF | (1.032Mb) |
| Abstract: | very-high-permittivity (e, = 100) multiband dielectrice> e resonator antenna is presented. The compact antenna, excited by a m:'crostrip line, resonates at two frequencies centered around the 1.9- GHz and 2.4-GHz bands with identical polarization . The behavior of the antenna at different positions along the feed line is studied and optimized. Multiple resonances with the same polarization and broad radioticn patterns suggest the suitability of the antenna for multiband wireless application |
| URI: | http://dyuthi.cusat.ac.in/purl/1404 |
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| A compact very- ... wireless applications.PDF | (1.327Mb) |
| Abstract: | A novel compact wideband antenna for wireless local area network (WLAN) applications in the 2.4 GHz band are presented. The proposed low profile antenna of dimensions 15 x 14.5 x 1.6 mm offers 18.6% bandwidth and an average gain of~5 dBi. The antenna can be excited directly using a 50 coaxial probe |
| URI: | http://dyuthi.cusat.ac.in/purl/1356 |
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| Compact wideban ... 4GHz WLAN applications.PDF | (928.7Kb) |
| Abstract: | A technique for improving the coupling between a feed horn and reflector by using corrugated metallic flanges is presented. Experimental data for flanges of varying parameters are given and theoretical explanation is supplemented |
| URI: | http://dyuthi.cusat.ac.in/purl/1430 |
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| Corrugated flan ... araboloidal reflectors.PDF | (1.323Mb) |
| Abstract: | A new method for enhancing the 2.1 VSWR impedance bandwidth of microstrip antennas is presented. Bandwidth enhancement is achieved by loading the microstrip antenna by a ceramic microwave dielectric resonator (DR). The validity of this technique has been established using rectangular and circular radiating geometries. This method improves the bandwidth of a rectangular microstrip antenna to more than 10% (= 5 times that of a conventional rectangular microstrip antenna) with an enhanced gain of I dB |
| URI: | http://dyuthi.cusat.ac.in/purl/1367 |
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| Dielecting-reso ... ndwidth and efficiency.PDF | (1.297Mb) |
| Abstract: | Ceramic dielectrics with high dielectric constant in the microwave frequency range are used as filters, oscillators [I], etc. in microwave integrated circuits (MICs) particularly in modern communication systems like cellular telephones and satellite communications. Such ceramics, known as 'dielectric resonators (DRs),donot only offer miniaturisation and reduce the weight of the microwave components. but also improve the efficiency of MICs |
| URI: | http://dyuthi.cusat.ac.in/purl/1437 |
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| Dielectric properties of Ba5Nb4O15 ceramic.PDF | (1.376Mb) |
| Dielectric properties of Ba5Nb4O15 ceramic.PDF | (1.376Mb) |
| Abstract: | A new design of' a dual-frequency dual-polarized square microsh'ip antenna fed along the diagonal, embedded with a square slot having three extended stubs for frequency tuning, is introduced. The proposed antenna was fabricated using a standard photolithographic method and the antenna was tested using the HP 3510(:; Vector Network Analyser. The antenna is capable of generating dual resonant frequencies with mutually perpendicular polarizations and broad radiation pattern characteristics. Such dual-frequency designs find wide applications in personal mobile handsets combining GSM and CDS 1800 modes, and applications in which different frequencies are used for emission and reception such as personal satellite communications and cellular network systems. |
| URI: | http://dyuthi.cusat.ac.in/purl/1397 |
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| Dual-frequency ... r communication system.PDF | (2.098Mb) |
| Abstract: | Experimental and simulated results for a dual-port dual-polarized microstrip antenna are presented. The antenna excites two orthogonally polarized resonant frequencies providing an isolation of -30 dB between the ports. The patch geometry consists of two circular arcs of different radii with their centers displaced by a distance. This new design offers an area reduction of -70% coinpared to it standard rectangular microstrip antenna with a reduction in gain of 1.7 dB |
| URI: | http://dyuthi.cusat.ac.in/purl/1391 |
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| Dual-band dual- ... act microstrip antenna.PDF | (907.1Kb) |
Now showing items 1-20 of 65
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