(16EC425)
UNIT-I
Microwave Transmission Lines: Introduction, Microwave spectrum and bands, applications of Microwaves. Waveguides-Solution of Wave Equation in Rectangular Coordinates, TE/TM mode analysis, Expressions for fields, Characteristic equation and cutoff frequencies, filter characteristics, dominant and degenerate modes, sketches of TE and TM mode fields in the cross-section. Mode characteristics- Phase and Group velocities, wavelengths and impedance relations, Illustrative Problems.
Rectangular Waveguides– Power Transmission and Power Losses, Impossibility of TEM Modes, Micro strip lines-introduction, Z0 relations, effective dielectric constant, losses, Qfactor, Cavity resonators-introduction, Rectangular and cylindrical cavities, dominant modes and resonant frequencies, Q-factor and coupling coefficients, Illustrative Problems.
UNIT-II
Waveguide Components And Applications: Coupling mechanisms- probe, loop, aperture types. Wave guide discontinuities-waveguide Windows, tuning screws and posts, matched
loads. Waveguide attenuators-resistive card, rotary vane Attenuators; waveguide phase shifters-dielectric, rotary vane phase shifters. Wave guide multiport junctions-E plane and H
plane Tees, Magic Tee, Directional couplers-2 hole, Bothe hole types, Illustrative Problems. Ferrites-composition and characteristics, Faraday rotation; Ferrite components-Gyrator,
Isolator, Circulator.
UNIT-III
Microwave Tubes: Limitations and losses of conventional tubes at microwave frequencies. Microwave tubes-O type and M type classifications. O type tubes: 2 cavity klystronsstructure, Reentrant cavities, velocity modulation process and Applegate diagram, bunching process and small signal theory-Expressions for O/P power and efficiency. Reflex Klystronsstructure, Velocity Modulation, Applegate diagram, mathematical theory of bunching, power output, efficiency, oscillating modes and O/P characteristics, Effect of Repeller Voltage on Power O/P, Illustrative Problems. HELIX TWTS: Significance, types and characteristics of slow wave structures; structure of TWT and amplification process (qualitative treatment), suppression of oscillations, gain considerations.
UNIT-IV
M-Type Tubes: Introduction, cross field effects, Magnetrons-different types, cylindrical travelling wave magnetron-Hull cutoff and Hartree conditions, modes of resonance and PImode operation, separation of PI-mode, O/P characteristics, Illustrative Problems. MICROWAVE SOLID STATE DEVICES: Introduction, classification, applications,
Transfer Electronic Devices, Gunn diode-principles, RWH theory, characteristics, basic modes of operation – Gunn oscillation modes. LSA Mode, Varactor Diode, Parametric
Amplifier, Introduction to Avalanche Transit time devices (brief treatment only)
UNIT-V
Microwave Measurements: Scattering Matrix-Significance, Formulation and properties. S Matrix calculations for 2port junction, E plane and H plane Tees, Magic Tee, Directional
coupler, circulator and Isolator, Illustrative Problems Description of Microwave benchdifferent blocks and their features, errors and precautions; Microwave power measurementBolometers, Measurement of attenuation, frequency standing wave measurements – measurement of low and high VSWR, cavity Q, impedance measurements.
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