Department of Electrical and Electronics Engineering
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Item Investigation on the aspect ratio of conducting superstrates in deciding its function as a gain enhancer/suppressor for wideband slot antenna(Springer, 2022-07) Kumar, A. V. PraveenThis paper presents an investigation on the effect of the aspect ratio (AR or width-to-length ratio) of a conducting sheet for radiation control i.e., gain enhancement or suppression, leading to useful applications for wireless communication. A wideband slot antenna working in 6–8.5 GHz band is adopted as the basic antenna. It is found that for the sheet AR < 1, the boresight (θ = 0°) gain in the entire band is enhanced, while for AR > 1, boresight gain suppression is achieved. For an optimum AR such that AR(enhancement) = 1/AR(suppression), the same sheet can serve the above dual purposes according to its azimuthal orientation with respect to the slot. For ϕ = 0° orientation with respect to the slot, the sheet acts as a gain enhancer, while for ϕ = 90° orientation, it suppresses the radiation, both in θ = 0°. Practically, the sheet orientation can be easily controlled manually. Antenna measurements demonstrate an impedance band of 6–8.66 GHz with bidirectional radiation pattern, and 1.11 dBi boresight gain at 7.25 GHz. A conducting sheet of size 1.45λ0 × 0.29λ0 where λ0 is the free-space wavelength at 7.25 GHz, is loaded above the slot which improves the boresight gain by 5.77 dB, and when rotated by ϕ = 90°, suppresses the gain by 8.78 dB, both relative to the original slot antenna.Item 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 Magnetic quadrupole mode excitation of a cylindrical dielectric resonator antenna using planar feed(Wiley, 2019-10) Kumar, A. V. PraveenIn this article, excitation of the magnetic quadrupole mode of a cylindrical dielectric resonator antenna, designated as the HEM21δ mode, using planar feeding technique is discussed for the first time. Two types of planar feeds—a dual-microstrip feed and a dual-slot feed are numerically investigated. Results show that the dual-slot feed is more suitable for exciting the HEM21δ mode as it gives better symmetry of the radiation pattern and lower cross-polarization level. A DRA prototype (dielectric constant, εr = 24, loss tangent, tanδ = 0.002, diameter, 2a = 19.43 mm and height, h = 7.3 mm) using dual-slot feed is fabricated and characterized. Measurements demonstrate a resonant frequency of ~ 4.96 GHz, bandwidth of ~4.4%, peak gain of ~3.45 dBi and peak cross-polar level of ~ − 11 dB for the HEM21δ mode, which are in decent agreement with numerical predictions.Item Investigation on the aspect ratio of conducting superstrates in deciding its function as a gain enhancer/suppressor for wideband slot antenna(ACM Digital Library, 2022-09) Kumar, A. V. PraveenThis paper presents an investigation on the effect of the aspect ratio (AR or width-to-length ratio) of a conducting sheet for radiation control i.e., gain enhancement or suppression, leading to useful applications for wireless communication. A wideband slot antenna working in 6–8.5 GHz band is adopted as the basic antenna. It is found that for the sheet AR < 1, the boresight (θ = 0°) gain in the entire band is enhanced, while for AR > 1, boresight gain suppression is achieved. For an optimum AR such that AR(enhancement) = 1/AR(suppression), the same sheet can serve the above dual purposes according to its azimuthal orientation with respect to the slot. For ϕ = 0° orientation with respect to the slot, the sheet acts as a gain enhancer, while for ϕ = 90° orientation, it suppresses the radiation, both in θ = 0°. Practically, the sheet orientation can be easily controlled manually. Antenna measurements demonstrate an impedance band of 6–8.66 GHz with bidirectional radiation pattern, and 1.11 dBi boresight gain at 7.25 GHz. A conducting sheet of size 1.45λ0 × 0.29λ0 where λ0 is the free-space wavelength at 7.25 GHz, is loaded above the slot which improves the boresight gain by 5.77 dB, and when rotated by ϕ = 90°, suppresses the gain by 8.78 dB, both relative to the original slot antenna.