Department of Electrical and Electronics Engineering
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Item A multifrequency coaxial-fed metal coated dielectric resonator antenna(Wiley, 2005-10) Kumar, A. V. PraveenA simple metal-coated dielectric resonator antenna with a coaxial feed producing multiple frequencies with similar polarization is reported. The characteristics of the antenna at all these frequencies are measured. The experimental results show that, the antenna produces broad patterns at all the operating frequencies. This antenna finds applications in frequency-agile systemsItem Coaxial fed hexagonal dielectric resonator antenna for circular polarization(Wiley, 2006-01) Kumar, A. V. PraveenA coaxial-fed hexagonal dielectric resonator antenna (HDRA) producing circular polarization is investigated experimentally. Circular polarization is achieved by exciting the orthogonal HE11δ modes of the HDRA in phase quadrature. The return-loss, impedance, and radiation characteristics are studied. The results show that the antenna produces circular polarization in the elevation plane with an axial ratio less than 3 dB over a bandwidth of 14.84% and a beam width of 66°.Item Hexagonal dielectric resonator antenna for 2.4 GHz WLAN applications(Wiley, 2006-11) Kumar, A. V. PraveenA dielectric resonator antenna (DRA) with hexagonal geometry for WLAN applications is proposed. The antenna is excited with a simple 50 Ω microstrip transmission line. The proposed antenna produces an impedance bandwidth of 105 MHz from 2.395 to 2.50 GHz, which covers the 2.4 GHz wireless local area networks band (WLAN: 2.4–2.485 GHz). The radiation patterns are measured and are found to be omnidirectional. An average gain of 5.4 dBi is measured in the operating band.Item Two-dimensional microwave tomographic imaging of low-water-content tissues(Wiley, 2005-07) Kumar, A. V. PraveenMicrowave tomographic imaging is explored in order to analyze the contrast in dielectric properties of low-water-content tissues such as bone and bone marrow. Two-dimensional tomographic images and dielectric-permittivity profiles of a calf femur are reconstructed from experimentally collected scattered fields, using the distorted Born iterative method (DBIM). The effects of bound water content on the dielectric permittivities of bone and bone marrow are studied. This approach has an application in the medical field for painless, cost-effective, and early diagnosis of leukemia in humans.Item Microstripline fed cylindrical dielectric resonator antenna for dual-band operation(Wiley, 2005-08) Kumar, A. V. PraveenA cylindrical dielectric resonator antenna (DRA) fed by microstripline giving dual-band operation with similar polarization is investigated. A single 50Ω microstrip transmission line excites the proposed DRA. The reflection and transmission characteristics of the antenna are discussed.Item Microstripline-fed half-cylindrical dielectric resonator antenna for 2.4-GHz WLAN application(Wiley, 2006-02) Kumar, A. V. PraveenA compact half-cylindrical dielectric resonator antenna (DRA) made from a high-permittivity (εr = 69) ceramic material is investigated. A microstrip transmission line excites the DRA. The DRA shows broad and stable radiation characteristics across a matching band of 2.32 to 2.5 GHz with peak gains of 5.5 dBi in the elevation plane and 3.6 dBi in the azimuth plane. The results lead us to propose this DRA for 2.4-GHz WLAN (2.4 to 2.484 GHz) application.Item Microstripline Fed Cylindrical Dielectric Resonator Antenna with a Coplanar Parasitic Strip(PIER, 2006) Kumar, A. V. PraveenThe paper discusses the experimental analysis on a cylindrical dielectric resonator antenna (DRA) with a parasitic conducting strip, loaded coplanar with the 50Ω microstripline feed. The antenna offers an impedance bandwidth as high as 17.33% at a centre frequency of 2.77 GHz, as a result of the enhanced coupling produced by the coplanar strip. The return loss, impedance, polarization and radiation characteristics of the antenna are studied. The radiation patterns are broad and the low cross-polarisation levels confirm that the antenna is linearly polarised over the entire impedance bandwidthItem A strip loaded dielectric resonator antenna for circular polarisation(Wiley, 2006-04) Kumar, A. V. PraveenThe paper presents an experimental investigation of a cylindrical dielectric resonator antenna (DRA) with a conducting strip loaded on its top surface enabling circular polarisation. A simple 50Ω microstrip transmission line excites the antenna. The reflection, polarisation, and radiation characteristics of the antenna are studied. The antenna exhibits circular polarisation with an axial ratio (AR) < 3 dB over a bandwidth of 3.14% and a beam width of 60°. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1354–1356, 2006; Published online in Wiley InterScienceItem A Wideband Conical Beam Cylindrical Dielectric Resonator Antenna(IEEE, 2007-07) Kumar, A. V. PraveenThe letter proposes a novel cylindrical dielectric resonator antenna (DRA) geometry with low radiation Q-value facilitating wide band operation with conical radiation patterns. The DRA is fed by a microstrip transmission line with a vertical strip that is attached to the DRA surface. At optimum dimensions and position of the vertical strip on the horizontal microstrip, the DRA exhibits an impedance bandwidth ( |S11|<−10 dB) of ∼35% at the centre frequency of 3 GHz. Measured radiation patterns are conical in shape and are stable with moderate gain across the matching band.