Balamati Choudhury

Terahertz Antenna Technology for Space Applications

The terahertz (THz) band provides a transition between the electronic and the photonic regions thus adopting important characteristics from these regimes. These characteristics corresponding with the progress in semiconductor technology has enabled researchers to exploit hitherto unexplored domains including satellite communication, biomedical imaging, security systems, etc. This book, explores the terahertz antenna technology toward implementation of compact, consistent, and cheap terahertz sources, as well as the high-sensitivity terahertz detectors. The advances in new materials and nanostructures such as graphene will be helpful in miniaturization of antenna technology while simultaneously maintaining the desired output levels. Terahertz antenna characterization of bandwidth, impedance, polarization, etc. has not yet been methodically structured and it continues to be a major research challenge. This book addresses these issues besides including the advances of terahertz technology in space applications worldwide, along with possibilities of using this technology in deep space networks.

A PSO application for locating defective elements in antenna arrays

In this paper an approach using the Particle Swarm Optimization(PSO) is proposed which allows to locate the defective elements in an antenna array. A cost function has been proposed using the array factor of the defected array that can lead to the location of the defective antenna elements in the array. Complete fault as well as partial fault elements are considered in the formulation. Although in this paper the formulation has been developed for linear array, it can easily be extended to case of a planar array.

Permittivity and Permeability Tensors for Cloaking Applications

An optimal version of electromagnetic (EM) stealth is the design of invisibility cloak of arbitrary shapes in which the EM waves can be controlled within the cloaking shell by introducing a prescribed spatial variation in the constitutive parameters. The promising challenge in design of invisibility cloak lies in the determination of permittivity and permeability tensors for all the layers. This book provides the detailed derivation of analytical expressions of the permittivity and permeability tensors for various quadric surfaces within the 11 Eisenhart co-ordinate systems. These include the cylinders and the surfaces of revolutions. The analytical modelling and spatial metric for each of these surfaces are provided along with their tensors. This mathematical formulation will help the EM designers to analyze and design various quadratics and their hybrids, which can eventually lead to the designing of cloaking shells of arbitrary shapes.

Metamaterial based K band substrate integrated waveguide filter for advanced communication systems

The next generation communication system demands for high data rate transfer leading towards exploring a higher level of frequency spectrum. In view of this demand, design of substrate integrated waveguide filters has been presented here in conjunction with metamaterial technology to increase the performance. A metamaterial based substrate integrated waveguide filter operating in the K band (18 – 26.5 GHz) has been demonstrated in this paper with the insertion loss of −0.57 dB in passband and provides a rejection band of 4.1 GHz.

Design optimization of PBG based PIFA system using soft computing techniques

Planar inverted F antennas have wide range of applications in wireless industry those includes mobile handset antennas, wireless sensors in aircraft fuel tanks to check the fuel availability status etc. One of the game changing technologies of wireless industry is design and development of compact, light weight antenna with low specific absorption rate. The antenna size can significantly be reduced by introducing metamaterial structures. In this paper, design optimization of a photonic band gap structure based compact, high impedance bandwidth planar inverted F antenna has been reported. The optimized antenna shows an impedance bandwidth of 39.9% and a gain of 6.03 dB whereas the conventional PIFA is of 25.4% only.

Electromagnetic Perspective of Tensors

The computational electromagnetics for planar applications generally deals with scalars and vectors, whereas the conformal analysis which is an essential requirement in aerospace platform relies on the electromagnetic analysis beyond scalars and vectors, i.e., the tensors of rank 2. This chapter gives an insight into the fundamentals of electromagnetic tensors and their analysis. Starting from the concepts of scalars and vectors, tensors have been introduced and their significance is discussed.

Design Optimization of Cloaks

The advancement in metamaterial science has turned the concept of electromagnetic cloaking from fiction to reality and fascinated many researchers towards the design and analysis of metamaterial unit cells. This chapter explores the design and analysis of one-layer cylindrical cloak using square SRR unit cell. Also different planar and conformal metamaterial structures have been designed and analyzed over a wide band of frequency, varying from microwave to terahertz range. The conformal unit cells exhibit more negative dielectric characteristics as compared to planar structures, making them more suitable for cloaking applications. Also the effect of radius of curvature on permittivity and permeability of unit cell has been analyzed and explained briefly.

Design and Optimization of Multilayer Ideal Cloak

Radar cross-section reduction through invisibility cloaking concept have been explored as a futuristic stealth technology. This novel concept upon realization can provide the optimal version of stealth to the aerospace domain. This chapter provides a technical insight to the design of ideal cylindrical and spherical cloaking structures in accordance with the transformation optics theory along with the feasibility study of this concept to aerospace platform. The simulations shown in this chapter are performed by using FEM based COMSOL Multiphysics software. The performance of the designed ideal spherical cloak is analyzed by comparing the radar cross-section of PEC sphere without cloaking and with multilayer cloaking shells. The multilayer spherical cloak shows reduced radar cross-section in C band as compared to PEC sphere.

Design Optimization of Broadband Radar Absorbing Structures

Radar cross section (RCS) reduction is a prominent field of research for achieving stealth in military domain. Stealth technology also called as low observable (LO) technology is the technique to make friendly aircraft and warships less visible to the enemy’s radar and detection capabilities, in order to enhance its survival. This chapter explores the practice of metamaterial inspired radar absorbing structures for achieving stealth in military domain. Design and analysis of two different metamaterial absorbers has been proposed along with broadbanding techniques. Electromagnetic computational tool in conjunction with soft computing optimization has been used to achieve optimum performance of the absorbers. Further, RCS measurement results has been reported to show the effectiveness of the absorber.

Metamaterial-Based Miniaturized Planar Inverted-F Antenna

Planar inverted F antennas are well known and widely used in the mobile communication industry. The rapid growth and high demand in the high performance mobile devices, with weight constraint, low specific absorption rate has put a challenge to the scientific community. Introduction of metamaterials as substrate or superstrate can be a revolution to this challenging task. This chapter provides an insight to the design and development of metamaterial based PIFA systems with low specific absorption rate. Various metamaterial structures have been designed and the effect on the return loss characteristics has been detailed in this chapter.