rectangular notches are determined to be 1.5 mm (d) and 8 ϫ 4 mm 2 (t ϫ h) in this study. The measured result for a corresponding planar cross-plate monopole antenna is also shown for comparison. Note that the proposed bent cross-plate monopole antenna occupies a cross-sectional area of only 25% that of the corresponding planar cross-plate monopole antenna (15 ϫ 15 mm 2 versus 30 ϫ 30 mm 2 ). From the measured return loss, we can observe that the effect of bending a planar metal plate into a step-shaped metal plate upon the impedance matching of the antenna is small, and the two antennas both show a very wide operating bandwidth. For the proposed antenna, the impedance bandwidth defined by 10-dB return loss is about 10 GHz (from 1.85 to 11.93 GHz) or has an edge frequency ratio of larger than 1:6.The radiation patterns were also measured. Figures 3, 4, and 5 plot the measured radiation patterns of the proposed antenna at 4, 7, and 11 GHz, respectively. Omnidirectional or near-omnidirectional radiation patterns in the azimuthal ( x-y) plane for frequencies across the wide impedance bandwidth are obtained. Figure 6 shows the measured antenna gain against frequency. For lower frequencies in the operating band, the antenna gain in general increases with frequency (from about 2.7 to 7.0 dBi), while for higher frequencies in the operating band, a stable antenna gain level of about 7.0 dBi is seen.
CONCLUSIONA compact wideband cross-plate monopole antenna has been proposed. The antenna has a cross-sectional area of only 25% that of a corresponding planar cross-plate monopole antenna. Furthermore, the proposed antenna can generate omnidirectional or nearomnidirectional radiation patterns for frequencies across a wide operating bandwidth of about 10 GHz (1. 85-11.93 GHz in this study). rectangular waveguide filled with a single negative metamaterial slab was studied. Cutoff frequencies along with the propagation constant  were numerically obtained for various single negativematerial constitutive slabs. Discontinuities in a grounded DNG slab waveguide, sandwiched between two regular dielectric slabs, were also analyzed in [6]. The anomalous dispersion characteristics were explored. The dispersion diagrams for the TM modes were found to be bent in a special region. They did not increase monotonically with normalized thickness, as is the case with conventional grounded-dielectric slab waveguides.In this paper, a grounded DNG slab waveguide is studied by examining its field dispersion. The dispersion relations of TM modes and TE modes are derived analytically and numerical results for the dispersion relations are obtained by using the graphical technique. Comparisons with the conventional grounded dielectric slab waveguide are made.
DERIVATION OF THE DISPERSION RELATIONSHIPThe geometry of a grounded DNG metamaterial slab waveguide is shown in Figure 1. The proposed DNG slab is assumed to be lossless and has a thickness of d, with both real negative permittivity ( r1 Ͻ 0) and permeability ( r1 Ͻ 0). For d Յ x Ͻ ϱ, a free-s...
Abstract:The purpose of this paper is to present a new and faster algorithmic procedure for generating the nbit Gray codes. Thereby, through this paper we have presented the derivation, design and implementation of a newly developed algorithm for the generation of an n-bit binary reflected Gray code sequences. The developed algorithm is stemmed from the fact of generating and properly placing the min-terms from the universal set of all the possible min-terms [m 0 m 1 m 2 …. m N ] of Boolean function of n variables, where, 0 < N < 2 n -1. The resulting algorithm is in concise form and trivial to implement. Furthermore, the developed algorithm is equipped with added attributes of optimizing of time and space while executed.
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