The design and development of low radar cross section (RCS) phased array has been a challenging subject in stealth technology. The frequency selective surface elements act as absorbers in specific frequency band and facilitate gain enhancement and reduction of antenna RCS. This book presents a comprehensive EM design and analysis of such low-profile patch arrays with high impedance surface-based ground plane. It explains how to determine radiation mode RCS of low-profile antenna arrays with arbitrary configurations. Detailed descriptions of design, workflow of determining radiation and scattering behavior of antenna arrays have been supported with schematics, tables, and illustrations. Aimed at engineers and researchers for RCS, antenna engineers and graduate students in electrical engineering and electromagnetics, it • Discusses both radiation and scattering features of both planar and conformal HIS-based low profile antennas • Describes the theoretical background, design, simulations and analysis of low RCS phased array in detail • Presents the physics behind the resultant radiation and scattering characteristics of designed antenna array • Helps readers understand design and analysis of low RCS antenna array without any degradation in its radiation performance • Includes figures, schematics and illustrations to provide comprehensive descriptions of both radiation and scattering characteristics of phased arrays of different configurations

Stealth technology is a crucial pre-requisite in the combat zone, where swiftness, surprise and initiative are the decisive elements for survivability. The supreme goal here is to reduce the visibility of military vehicles by shaping, application of radar absorbing materials, passive cancellation, active cancellation etc. With respect to multilayered radar absorbing structures (RAS), this book presents an efficient algorithm based on particle swarm optimization (PSO), for the material selection as well as optimization of thickness of multilayered RAS models considering both normal as well as oblique incidence cases. It includes a thorough overview of the theoretical background required for the analysis of multilayered RAS as well as the step-by-step procedure for the implementation of PSO-based algorithm. The accuracy and computational efficiency of the indigenously developed code is also clearly established using relevant validations and case studies. FEATURES Provides step-by-step procedure for the implementation of particle swarm optimization (PSO) based algorithm in the context of multilayered radar absorbing structures (RAS) design Helps to understand the EM design, analysis and optimization of multilayered RAS Describes the theoretical background required for the analysis of multilayered RAS Illustrates in detail the theoretical formulation supported by intuitive ray diagrams and comprehensive flowcharts to implement the algorithm with ease Includes elaborate validations and case studies This book will serve as a valuable resource for students, researchers, scientists, and engineers involved in the electromagnetic design and development of multi-layered radar absorbing structures.

Stealth technology is a crucial pre-requisite in the combat zone, where swiftness, surprise and initiative are the decisive elements for survivability. The supreme goal here is to reduce the visibility of military vehicles by shaping, application of radar absorbing materials, passive cancellation, active cancellation etc. With respect to multilayered radar absorbing structures (RAS), this book presents an efficient algorithm based on particle swarm optimization (PSO), for the material selection as well as optimization of thickness of multilayered RAS models considering both normal as well as oblique incidence cases. It includes a thorough overview of the theoretical background required for the analysis of multilayered RAS as well as the step-by-step procedure for the implementation of PSO-based algorithm. The accuracy and computational efficiency of the indigenously developed code is also clearly established using relevant validations and case studies. FEATURES Provides step-by-step procedure for the implementation of particle swarm optimization (PSO) based algorithm in the context of multilayered radar absorbing structures (RAS) design Helps to understand the EM design, analysis and optimization of multilayered RAS Describes the theoretical background required for the analysis of multilayered RAS Illustrates in detail the theoretical formulation supported by intuitive ray diagrams and comprehensive flowcharts to implement the algorithm with ease Includes elaborate validations and case studies This book will serve as a valuable resource for students, researchers, scientists, and engineers involved in the electromagnetic design and development of multi-layered radar absorbing structures.

The design and development of low radar cross section (RCS) phased array has been a challenging subject in stealth technology. The frequency selective surface elements act as absorbers in specific frequency band and facilitate gain enhancement and reduction of antenna RCS. This book presents a comprehensive EM design and analysis of such low-profile patch arrays with high impedance surface-based ground plane. It explains how to determine radiation mode RCS of low-profile antenna arrays with arbitrary configurations. Detailed descriptions of design, workflow of determining radiation and scattering behavior of antenna arrays have been supported with schematics, tables, and illustrations. Aimed at engineers and researchers for RCS, antenna engineers and graduate students in electrical engineering and electromagnetics, it * Discusses both radiation and scattering features of both planar and conformal HIS-based low profile antennas * Describes the theoretical background, design, simulations and analysis of low RCS phased array in detail * Presents the physics behind the resultant radiation and scattering characteristics of designed antenna array * Helps readers understand design and analysis of low RCS antenna array without any degradation in its radiation performance * Includes figures, schematics and illustrations to provide comprehensive descriptions of both radiation and scattering characteristics of phased arrays of different configurations

This book presents a novel methodology for the computation of RCS of metallic structures using a parallelized version of NEC in conjunction with a finite element preprocessor which has been strategically incorporated for simplifying geometry modelling catering to NEC guidelines. It includes a thorough overview of the theoretical background of NEC including all relevant aspects of formulation and modelling. The revised methodology including all the required steps and details is discussed elaborately along with case studies and validations. This book will serve as a valuable resource for students, researchers, scientists, and engineers working in the field of RCS predictions and measurements.

This book focuses on determination of scattering of parallel-fed planar dipole arrays in terms of reflection and transmission coefficients at different levels of the array system. In aerospace vehicles, the phased arrays are often in planar configuration. The radar cross section (RCS) of the vehicle is mainly due to its structure and the antennas mounted over it. There can be situation when the signatures due to antennas dominate over the structural RCS of the platform. This necessitates the study towards the reduction and control of antenna/ array RCS. The planar dipole array is considered as a stacked linear dipole array. A systematic, step-by-step approach is used to determine the RCS pattern including the finite dimensions of dipole antenna elements. The mutual impedance between the dipole elements for planar configuration is determined. The scattering till second-level of couplers in parallel feed network is taken into account. The phase shifters are modelled as delay line. All the couplers in the feed network are assumed to be four port devices. It is shown that the array RCS can be reduced considerably for a low observable platform by an optimization of array design parameters even in the presence of mutual coupling. This book presents a systematic step-by-step analytical formulation for RCS of planar half-wavelength centre-fed dipole arrays through various schematics and illustrations. The analytical description and analysis provided in this book should be useful for students, researchers, and design engineers of phased arrays.

Decreasing trends of organic matter and plant-available nutrients in arable soils, other negative consequences of fertilizer inputs and frequent tillage call for newer techniques in agriculture, one such technique which has attracted considerable interest is microbial management. Microbial biomass is a small active fraction of the soil organic matter which turns over very rapidly, and holds a large pool of plant-available nutrients. It acts as a source and a sink of nutrients and is responsive to several agricultural practices. Soil organic carbon (SOC) has also been identified as a factor that is important to soil fertility as well as for the environment because of huge carbon sequestration potential of the soils. Present study was undertaken to evaluate the influence of applications of straw and chemical fertilizer on the soil microbial biomass, available nutrient pools and crop growth under reduced tillage, dryland conditions. The major hypothesis tested in this study was that the management practices which can increase the size of active soil organic pool can enhance the nutrient supply rate and hence crop growth in drylands under reduced tillage cultivation