Some Efficient Representations of 3D Information based on Octress

The thesis introduced the octree and addressed the complete nature of problems encountered, while building and imaging system based on octrees. An efficient Bottom-up recursive algorithm and its iterative counterpart for the raster to octree conversion of CAT scan slices, to improve the speed of generating the octree from the slices, the possibility of utilizing the inherent parallesism in the conversion programme is explored in this thesis. The octree node, which stores the volume information in cube often stores the average density information could lead to “patchy”distribution of density during the image reconstruction. In an attempt to alleviate this problem and explored the possibility of using VQ to represent the imformation contained within a cube. Considering the ease of accommodating the process of compressing the information during the generation of octrees from CAT scan slices, proposed use of wavelet transforms to generate the compressed information in a cube. The modified algorithm for generating octrees from the slices is shown to accommodate the eavelet compression easily. Rendering the stored information in the form of octree is a complex task, necessarily because of the requirement to display the volumetric information. The reys traced from each cube in the octree, sum up the density en-route, accounting for the opacities and transparencies produced due to variations in density.

Design and Development of Compact Coplanar Waveguide Fed Antennas for Wireless Applications

The need of miniaturization in the present day communication industry is challenging. In the present scenario, printed antenna technology is highly suitable for wireless communication due to its low profile and other desirable radiation characteristics. Small monopole type antennas are overruled by compact small antennas for present day mobile communication applications. Coplanar waveguides (CPW) are printed on one side of a dielectric substrate. CPW have attracted the attention of antenna designers due to their excellent properties like ease of integration with ‘MMIC’, low cost, wide bandwidth, flexibility towards multiband operation, low radiation leakage and less dispersion. The requirement of omnidirectional coverage, light weight and low cost made these CPW fed antennas a good candidate for wireless applications. The main focus of the thesis is the study of coplanar waveguide transmission line. Rigorous investigations were performed on both the ground plane and signal strip of a coplanar waveguide transmission line to create effective radiation characteristics. Good amount of works have been done to transform CPW line to antenna suitable for mobile phone applications