antennas and wave propagation


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, & 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.
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 & their characteristics. Helical Antennas, Helical 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.
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 reflectorsgeometry, pattern characteristics, Feed Methods, Reflector Types – Related Features, Lens Antennas – Geometry of Non-metallic Dielectric Lenses, Zoning , Tolerances, -Applications, Illustrative Problems.
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).
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, 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.

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