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SYLLABUS

UNIT-I

microwave Transmission Lines: Introduction, Microwave spectrum and bands, applications of Microwaves. Rectangular 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, Illustratives problems. Rectangular Waveguides – Power Transmission and Power Losses, Impossibility of TEM modes, Micro strip linesintroduction, Z0 relations, effective dielectric constant, losses, Q-factor, 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 phases shifters – dielectric, Rotary vane phase shifters. Waveguide multiport junctions – E plane and H plane Tees, Magic Tee, Directional couplers – 2 hole, Bethe 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 klystrons-structure, Reentrant cavities, Velocity modulation process and Applegate diagram, Bunching process and small signal theory – Expressions for o/p power and efficiency. Reflex Klystrons-structure, 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 MagnetronHull cutoff and Hartree conditions, Modes of resonance and PI-mode 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 2-port junction, E plane and H plane Tees, Magic Tee, Directional coupler, Circulator and Isolator, Illustrative Problems. Description of Microwave bench – Different blocks and their features, Errors and precautions; Microwave power measurement – Bolometers, Measurement of attenuation, frequency, Standing wave measurements, measurements of low and high VSWR, Cavity – Q, Impedance measurements.