BITS Faculty Publications
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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 Coaxial fed hexagonal dielectric resonator antenna for multifrequency operation(Wiley, 2006-03)Hexagonal dielectric resonator antenna (HDRA) for multifrequency operation is proposed and investigated experimentally. The proposed antenna, excited by a single coaxial feed, resonates at four frequencies centered at 2.215, 2.784, 3.445, and 3.955 GHz with identical polarization. The return loss, VSWR, bandwidth, radiation patterns and half-power beam width are measured and discussed. Multiple resonances with the same polarization and broad radiation patterns suggest the suitability of the antenna for multifrequency wireless applications.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 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 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.Item Parasitic Metal Loading to Purify the Higher-Order Mode of a Cylindrical Dielectric Resonator Antenna(SSRN, 2017-07) Kumar, A. V. PraveenThe paper shows that a metallic strip placed at certain planes of a Cylindrical Dielectric Resonator Antenna (CDRA) improves the purity of the co-polarized fields of its Higher Order Mode (HOM) when excited by a microstrip line. The metallic boundary suppresses the spurious field components of the HOM which are responsible for a distorted radiation pattern. A directivity of about –30 dB in the broadside direction and about 5.5 dB at ±500 elevation to the broadside has been demonstrated at the HOM frequency of 4.63 GHz. The metal loading also retains the fundamental broadside mode of the CDRA allowing dualband and dual-mode operation.Item Substrate size selection of microstrip-fed cylindrical dielectric resonator antennas for lowering the cross-polarisation(IET, 2019-01) Kumar, A. V. PraveenA cylindrical dielectric resonator antenna (DRA) has been excited with a microstrip line in the HEM11δ mode. It is demonstrated that at the operating frequency, minimum cross-polarisation occurs when the lateral dimension of the substrate is slightly higher than half a free-space wavelength (λ0). This occurs when direct waves from the DRA interfere appropriately with the waves that are diffracted from the substrate edges. For a 50 Ω microstrip-fed cylindrical DRA, numerical prediction suggests a substrate of lateral dimension 0.58λ0 for the lowest possible cross-polarisation. In addition, the above optimum substrate size is constant irrespective of the substrate shape (square or circle) or dielectric resonator (DR) properties (permittivity and aspect ratio) for a given substrate permittivity. Numerical results are experimentally verified for a DRA with permittivity 24 and aspect ratio 1.33, for both square and circular substrates at the respective operating frequencies.