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 |
Files | Size |
---|---|
Dielectric properties of Ba5Nb4O15 ceramic.PDF | (1.376Mb) |
Dielectric properties of Ba5Nb4O15 ceramic.PDF | (1.376Mb) |
Abstract: | Experimental studies on a compact dual frequency microstrip antenna are presented. This antenna configuration provides an area reduction of 40% compared to a standard rectangular antenna operating at the same frequency without much degradation of the gain. The antenna structure can be modified to achieve the desired ratio between the two resonant frequencies |
URI: | http://dyuthi.cusat.ac.in/purl/1375 |
Files | Size |
---|---|
Dual-band dual- ... act microstrip antenna.PDF | (907.1Kb) |
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 |
Files | Size |
---|---|
Dual-frequency ... r communication system.PDF | (2.098Mb) |
URI: | http://dyuthi.cusat.ac.in/purl/1351 |
Files | Size |
---|---|
Dual frequency miniature microstrip antenna.PDF | (807.9Kb) |
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 |
Files | Size |
---|---|
Dual-band dual- ... act microstrip antenna.PDF | (907.1Kb) |
Abstract: | The effect of dopants with different valencies and ionic radii on the densification, structural ordering, and microwave dielectric properties of Ba(Mg1t3Tazt3)O3 (BMT) is investigated. It is found that dopants such as Sb,05, MnO, ZrO,, WO1, and ZnO improve the microwave dielectric properties of BMT. Addition of trivalent dopants is detrimental to the cation ordering and dielectric properties of BMT. A correlation between the microwave dielectric properties of BMT and ionic radii of the dopant has been established. The variation of the dielectric properties of pure and doped BMT at cryogenic temperatures is also discussed |
URI: | http://dyuthi.cusat.ac.in/purl/1489 |
Files | Size |
---|---|
The effect of d ... o.33Ta0.67)03 ceramics.PDF | (5.114Mb) |
URI: | http://dyuthi.cusat.ac.in/purl/1491 |
Files | Size |
---|---|
Effect of Nonst ... of Ba(Mgo.33Tao.67)03.PDF | (6.590Mb) |
Abstract: | The effect of glass additives on the densification , phase evolution, microstructure and microwave dielectric properties of Ba(Mg1;3 Ta2i3)03 (BMT) was investigated . Different weight percentages of quenched glass such as B203 , Si02, B203-SiO2, ZnO-B203, 5ZnO-2B2O3, Al203-SiO2, Na20-2B203.10H20, BaO-B203-SiO2, MgO-B203-SiO2, PbO-B203-SiO2 , ZnO-B203-SiO2 and 2MgO-Al203-5SiO2 were added to calcined BMT precursor . The sintering temperature of the glass -added BMT samples were lowered down to 1300 °C compared to solid-state sintering where the temperature was 1650 °C. The formation of high temperature satellite phases such as Ba5Ta4O15 and Ba7Ta6O22 were found to be suppressed by the glass addition . Addition of glass systems such as B203, ZnO-B203, 5ZnO-2B203 and ZnO-B203-SiO2 improved the densification and microwave dielectric properties. Other glasses were found to react with BMT to form low-Q phases which prevented densification . The microwave dielectric properties of undoped BMT with a densification of 93 . 1 % of the theoretical density were Cr = 24 . 8, Tr = 8 ppm/°C and Q„ x f= 80,000 GHz. The BMT doped with 1.0 wt% of B203 has Q„ x f = 124,700GHz, Cr = 24.2, and T f = -1.3 ppm /°C. The unloaded Q factor of 0.2 wt% ZnO-B203-doped BMT was 136,500 GHz while that of 1.0 wt% of 5ZnO-2B203 added ceramic was Q„ x f= 141,800 GHz . The best microwave quality factor was observed for ZnO -B203-SiO2 (ZBS) glass-added ceramics which can act as a perfect liquid-phase medium for the sintering of BMT. The microwave dielectric properties of 0.2wt% ZBS-added BMT dielectric was Q„ x f= 152,800 GHz, F,= 25.5, and Tr = - 1.5 ppm/°C |
URI: | http://dyuthi.cusat.ac.in/purl/1495 |
Files | Size |
---|---|
Effect of Nonst ... of Ba(Mgo.33Tao.67)03.PDF | (6.590Mb) |
Abstract: | Nickel–rubber nanocomposites were synthesized by incorporating ferromagnetic nickel nanoparticles in a natural rubber as well as neoprene rubber matrix. Complex dielectric permittivity and magnetic permeability of these composites were evaluated in the X-band microwave frequencies at room temperature using cavity perturbation technique. The dielectric loss in natural rubber is smaller compared to neoprene rubber. A steady increase in the dielectric permittivity is observed with increase in the content of nickel in both the composites. The magnetic permeability exhibits a steady decrease with increase in frequency and magnetic loss shows a relaxation at 8 GHz. The suitability of these composites as microwave absorbers is modeled based on the reflection loss which is dependant on the real and imaginary components of the complex dielectric permittivity and magnetic permeability. |
Description: | Appl Phys A (2009) 97: 157–165 |
URI: | http://dyuthi.cusat.ac.in/purl/4402 |
Files | Size |
---|---|
Effect of nicke ... n rubber in the X-band.pdf | (1.140Mb) |
Abstract: | A new design of a dual-band dual-polarized electromagnetically coupled slot loaded square patch antenna, covering the WLAN 5.2 GHz and 5.8 GHz bands, 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. |
URI: | http://dyuthi.cusat.ac.in/purl/2720 |
Files | Size |
---|---|
Dyuthi-P00357.pdf | (629.0Kb) |
Abstract: | In this paper, a dual port, dual frequency, dual polarized, octagonal shaped Microstrip patch antenna, suitable for GPS applications is discussed experimentally and theoretically. The proposed antenna configuration is characterized by good impedance bandwidth, gain, isolation between two ports and broad radiation patterns |
Description: | Personal Wireless Communications, 2005. ICPWC 2005. 2005 IEEE International Conference on,PP 305-307 |
URI: | http://dyuthi.cusat.ac.in/purl/4336 |
Files | Size |
---|---|
Electromagnetic ... ctagonal Patch Antenna.pdf | (207.5Kb) |
Abstract: | A novel technique fitr the bat dividth enhancement of conventional rectangular microstrip antenna is proposed in this paper. When a high permittivity dielectric resonator of suitable resonant frequency was loaded over the patch. the % bandwidth of the antenna was increased by more than five tunes without much affecting its gain and radiation performance. A much more improved bandwidth was obtained when the dielectric resonator was placed on the feedline. Experimental study shows a 2:1 VSWR bandwidth of more than 10% and excellent cross polarization performance with increased pass band and radiation coverage abnost the same as that of rectangular microstrip antenna |
URI: | http://dyuthi.cusat.ac.in/purl/1389 |
Files | Size |
---|---|
Enhanced bandwi ... dielectric resonators.PDF | (1.874Mb) |
Abstract: | In this thesis, we explore the design, computation, and experimental analysis of photonic crystals, with a special emphasis on structures and devices that make a connection with practically realizable systems. First, we analyze the propenies of photonic-crystal: periodic dielectric structures that have a band gap for propagation. The band gap of periodically loaded air column on a dielectric substrate is computed using Eigen solvers in a plane wave basis. Then this idea is extended to planar filters and antennas at microwave regime. The main objectives covered in this thesis are:• Computation of Band Gap origin in Photonic crystal with the abet of Maxwell's equation and Bloch-Floquet's theorem • Extension of Band Gap to Planar structures at microwave regime • Predict the dielectric constant - synthesized dieletric cmstant of the substrates when loaded with Photonic Band Gap (PBG) structures in a microstrip transmission line • Identify the resonant characteristic of the PBG cell and extract the equivalent circuit based on PBG cell and substrate parameters for microstrip transmission line • Miniaturize PBG as Defected Ground Structures (DGS) and use the property to be implemented in planar filters with microstrip transmission line • Extended the band stop effect of PBG / DGS to coplanar waveguide and asymmetric coplanar waveguide. • Formulate design equations for the PBG / DGS filters • Use these PBG / DGS ground plane as ground plane of microstrip antennas • Analysis of filters and antennas using FDID method |
Description: | Department of Electronics, Cochin University of Science and Technology |
URI: | http://dyuthi.cusat.ac.in/purl/2704 |
Files | Size |
---|---|
Dyuthi-T0756.pdf | (14.56Mb) |
Abstract: | Results of exhaustive study of the effect of metallic flanges on H-plane radiation characteristics of V-slot waveguide antenna are presented . It has been established that the beam can be sharpened or broadened by varying the flange angle . The adjustment of the flange angle and flange width would further improve the radiation pattern , yielding optimum efficiency from the flanged system |
URI: | http://dyuthi.cusat.ac.in/purl/1436 |
Files | Size |
---|---|
An experimental ... slot waveguide antenna.PDF | (1.063Mb) |
Abstract: | A theoretical analysis of a symmetric T-shaped rnicrostripfed rectangular microstrip antenna using the finite-difference titnedoniain (FDTD) method is presented in this paper. The resonant frequency, return loss, impedance bandwidth, and radiation patterns are predicted and are in good agreement with the measured results |
URI: | http://dyuthi.cusat.ac.in/purl/1408 |
Files | Size |
---|---|
FDTD analysis o ... lar microstrip antenna.PDF | (850.6Kb) |
Abstract: | Flexile single layer electromagnetic wave absorbers were designed by incorporating appropriate amounts of carbon black in a nitrile butadiene rubber matrix along with an optimized amount of magnetic counterpart, namely, barium hexaferrite for applications in S, C, and X-bands. Effective dielectric permittivity and magnetic permeability were measured using cavity perturbation method in the frequency range of 2–12 GHz. The microwave absorbing characteristics of the composites were studied in the S, C, and X-bands employing a model in which an electromagnetic wave is incident normally on a metal terminated single layer. Reflection loss exceeding 20 dB is obtained for all the samples in a wide frequency range of 2–12 GHz when an appropriate absorber thickness between 5 and 9mm is chosen. The impact of carbon black is clearly observed in the optimized composites on the mechanical strength, thickness, band width of absorption, dielectric properties, |
Description: | J. Appl. Phys. 116, 024902 (2014) |
URI: | http://dyuthi.cusat.ac.in/purl/4426 |
Files | Size |
---|---|
Flexible microw ... 2–12 GHz applications.pdf | (2.341Mb) |
Abstract: | The flange technique, suggested by Reynolds72 is simple technique to improve antenna characteristics. Using flange technique we can trim the antenna characteristic by suitably adjusting the flange parameters75. Later corrugated flanges87 are used for beam shaping. The important parameters of the corrugated flanges are (a) flange angle, (b) flange width, (c) flange position, (d) conductivity of the flange, (e) amplitude excitation of the flange elements, (f) period of corrugation etc. Compared to a compound horn the flange technique offers great convenience in trimming antenna characteristics. Horns are commonly used as a feed in radar and satellite communications. A large number of work had been done to improve the characteristics of horn antennas. It is an established fact that grooved walls on the inner surface of a horn can improve the antenna characteristics44. Corrugated comb surface can be used for the circular polarization98, tilt of polarization99 etc. This suggests the possibility to combine these two phenomena and to obtain a resultant beam. This thesis presents the result of an investigation to study the possibility of controlling different antenna characteristics like polarization, beam shaping, matching etc, using corrugated flange techniques. |
Description: | Department of physics, Cochin University of Science And Technology |
URI: | http://dyuthi.cusat.ac.in/purl/3476 |
Files | Size |
---|---|
Dyuthi-T1473.pdf | (8.996Mb) |
URI: | http://dyuthi.cusat.ac.in/purl/1103 |
Files | Size |
---|---|
Mohanan P 1985.pdf | (1.825Mb) |
Abstract: | A novel compact chipless RFID tag using spurline resonators is discussed in this paper. The detection of the tag's ID is using the spectral signature of a spurline resonator circuit. The tag has a data capacity of 8-bits in the range 2.38 to 4.04 GHz. The tag consists of a spurline multiresonating circuit and two cross polarized antennas. The prototype of the tag is fabricated on a substrate CMET/ LK4.3 of dielectric constant 4.3 and loss tangent 0.0018. The measured results show that group delay response can also be used to decode the tag’s identity |
Description: | RADIOENGINEERING, VOL. 23, APRIL 2014 |
URI: | http://dyuthi.cusat.ac.in/purl/4338 |
Files | Size |
---|---|
Frequency Coded ... ng Spurline Resonators.pdf | (1.526Mb) |
Abstract: | Electromagnetic scattering behaviour of a superstrate loaded metallo– dielectric structure based on Sierpinski carpet fractal geometry is reported. The results indicate that the frequency at which backscattering is minimum can be tuned by varying the thickness of the superstrate. A reduction in backscattered power of 44 dB is obtained simultaneously for both TE and TM polarisations of the incident field. |
URI: | http://dyuthi.cusat.ac.in/purl/675 |
Files | Size |
---|---|
Frequency tunab ... ering reduction Anupam.pdf | (205.4Kb) |
Dyuthi Digital Repository Copyright © 2007-2011 Cochin University of Science and Technology. Items in Dyuthi are protected by copyright, with all rights reserved, unless otherwise indicated.