Analysis Of Dual Band Rectangular Microstrip Antenna Using IE3D/PSO

This thesis covers three aspects of Microstrip antenna designs. The first is the analysis and design of single element rectangular Microstrip antenna which operates at the central frequency of 2.4 GHz. The second aspect is the design of dual band rectangular microstrip antenna which operates at 2.4 & 3.08 GHz. Both antennas are modeled, designed and simulated. Here transmission line and cavity modeling are used to model both antennas. First, the design parameters for single element of rectangular patch antenna is calculated from the transmission line model equation and then the antenna design is exdended to Dual Band rectangular Microstrip patch antenna using the slots at radiating edge. The simulation process has been carried out through IE3D electromagnetic software which is based on method of moment (MOM). The third is the interfacing between IE3D and PSO (MATLAB).In this part optimization is done through Particle Swarm Optimization (PSO) and then the antenna is designed using IE3D simulation software

Investigations on some compact wideband fractal antennas

Today’s small handheld and other portable devices challenge antenna designers for ultrathin, and high performances that have the ability to meet multi standards. In the context, fractal geometries have significant role for antenna applications with varying degree of success in improving antenna characteristics. In this thesis, we have investigated several wideband fractal monopole antennas. This work starts with design and implementation of Koch fractal, hybrid fractal, sectoral fractal, semi-circle fractal monopole antennas with discussion, covering their operations, electrical behavior and performances. The performances of these designs have been studied using standard simulation tools used in industry/academia and are experimentally verified. Frequency reconfigurable Koch snowflake fractal monopole antenna is also introduced. The present antenna can be used as an array element and has a wideband frequency of operation. A square Sierpinski monopole antenna has been designed, which is suitable for use in indoor UWB radio system and outdoor base station communication systems. Technique for obtaining a band stop function in the 5-6 GHz frequency band is numerically and experimentally presented. In addition to examining the performance of UWB system, the transfer function and waveform distortion are discussed. Finally, fractal antenna for array with MIMO environment is developed for mobile communication devices. Aim of this work is to achieve the acceptable performances in terms of isolation, envelope correlation coefficient, capacity loss, radiation patterns and efficiency. Furthermore, a wideband feed network prototype based on a modified Wilkinson power divider is designed. The designed feed network has been used in constructing 2-element and 4-element linear antenna arrays for high gain. This research work has addressed the effectiveness of fractal geometries in antenna and to bring-out the true advantages of their in antenna engineering

Higher Order Bandpass Single and Dual Band Frequency Selective Surfaces With Aperture Coupled Patch Resonators

In this article, a low profile aperture coupled single and dual band higher order bandpass frequency selective surface (FSS) is proposed. Initially, a basic patch resonator with L-shape truncated corner is investigated theoretically so that two orthogonal modes can be excited simultaneously. Next, to avoid the cross-polarized reflection produced by two orthogonal modes, a combination of four such L-shape truncated patch resonators with 90° between two adjoining patches are implemented and analyzed.Further, by arranging two of such combination resonators placed back-to-back manner through aperture coupling metallic layer in middle, a three layer single mode fourth order and a dual band second order bandpass FSS is designed. The proposed bandpass FSS enables higher order bandpass FSSs where the order of the modes is twice than traditional aperture coupled patch resonators (AC-PRs). It provides more flexibility at higher order filtering responses. To endorse the design concept, a single and dual bandpass FSS is simulated to initiate magnetic and electric coupling through the aperture metallic layer. Moreover, an equivalent circuit model for the even and odd mode analysis method is examined the principle of operation. Finally, the proposed bandpass FSS is fabricated and tested in a vector network analyzer (VNA) setup. The measured and simulated results are compared and validated

Gain Enhancement in Microstrip Patch Antenna With High Negative Refractive Index 3D-Metamaterial Inspired Superstrate for Wireless Applications

This article presents a 3D-metamaterial (3D-MTM) structure to enhance microstrip patch antenna gain. A 3D-MTM unit cell exhibits an MNG ( $\mu$ -negative) property with a high negative refractive index over the 2.36-2.53 GHz frequency range resonating at 2.45 GHz. Therefore, a $4\times 4$ array of the proposed 3D-MTM unit cell is analyzed and used as a superstrate over a patch antenna and a $2\times 2$ array antenna to achieve high gain for wireless applications. The simulated and measured results of the designed antenna show that the gain is enhanced by about 5dBi and 3.2dBi. In addition, the half power beam width reduced in E-plane is 23° and 12.85° for a patch antenna and $2\times 2$ array antenna, respectively

Multiangle lidar observations of the Atmosphere

Atmospheric Lidars are used extensively to get aerosol parameters like backscatter coefficient, backscatter ratio etc. National Atmospheric Research Laboratory, Gadanki (13°N, 79°E), India has a powerful lidar which has alt-azimuth capability. Inversion method is applied to data from observations of lidar system at different azimuth and elevation angles. Data Analysis is described and Observations in 2D and 3D format are discussed. Presence of Cloud and the variation of backscatter parameters are seen in an interesting manner