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SYLLABUS

UNIT-I

Antenna Basics & Dipole Antennas : Introduction, Basic antenna parameters – Patterns, Beam area, Radiation intensity, Beam efficiency, Directivity-Gain-Resolution, Antenna apertures, Effective height, Fields from oscillating dipole, Field zones, Shape-Impedance considerations, Polarization – Linear, Elliptical and circular polarizations. Antenna temperature, Antenna impedance, Front-to-back ratio, Antenna theorems, Radiation – Basic Maxwell’s equations, Retarded potential – Helmholtz Theorem, Radiation from small electric dipole, Quarter wave monopole and half wave dipole – Current distributions, Field components, Radiated power, Radiation resistance, Beam width, Natural current distributions, Far fields and patterns of thin linear center-fed antennas of different lengths, Illustrative problems.

UNIT-II

VHF, UHF and Microwave Antennas-I : Loop antennas-Introduction, Small loop, Comparison of far fields of small loop and short dipole, Radiation resistances and directives of small and large loops (Qualitative Treatment), Arrays with parasitic elements - Yagi-Uda Arrays, Folded dipoles and their characteristics, Helical AntennasHelical geometry, Helix modes, Practical design considerations for monofilar helical antenna in axial and normal modes, Horn antennas-Types, Fermat’s principle, Optimum horns, Design considerations of pyramidal Horns, Illustrative Problems.

UNIT-III

VHF, UHF and Microwave Antennas-II : Micro strip antennas – Introduction, Features, Advantages and limitations, Rectangular patch antennas – Geometry and parameters, Characteristics of micro strip antennas, Impact of different parameters on characteristics, Reflector antennas – Introduction, Flat sheet and corner reflectors, Parabola reflectors – Geometry, Pattern characteristics, Feed methods, Reflector types – Related features, Lens antennas – Geometry of non-metallic dielectric lenses, Zoning, Tolerances, Applications, Illustrative Problems.

UNIT-IV

Antenna Arrays : Point sources – Definition, Patterns, Arrays of 2 isotropic sources – Different cases, Principle of pattern multiplication, Uniform linear arrays – Broadside arrays, Endfire arrays, EFA with increased directivity, Derivation of their characteristics and comparison, BSA with non-uniform amplitude distributions – General considerations and binomial arrays, Illustrative problems. Antenna Measurements : Introduction, Concepts – Reciprocity, Near and far fields, Coordination system, Sources of errors, Patterns to be measured, Pattern measurement arrangement, Directivity measurement, Gain measurements (By comparison, Absolute and 3-antenna methods).

UNIT-V

Wave Propagation: Introduction, Definitions, Characterizations and general classifications, Different modes of wave propagation, Ray/Mode concepts, Ground wave propagation (Qualitative treatment) – Introduction, Plane earth reflections, Space and surface waves, Wave tilt, Curved earth reflections, Space wave propagation – Introduction, Field strength variation with distance and height, Effect of earth’s curvature, Absorption, Super refraction, M-curves and duct propagation, Scattering phenomena, Tropospheric propagation, Fading and path loss calculations, Sky wave propagation – Introduction, Structure of ionosphere, Refraction and reflection of sky waves by ionosphere, Ray path, Critical frequency, MUF, LUF, OF, Virtual height and skip distance, Relation between MUF and skip distance, Multi-HOP propagation, Energy loss in ionosphere, Summary of wave characteristics in different frequency ranges, Illustrative problems.