## Microwave Engineering

#### Course Information

- Course Instructor J. Shri Hari Rao, NITW(Rtd.)
- Level Undergraduate
- Language English
- Course Duration 16 Weeks
- Course Start DEC 20, 2017

**Description**

Microwave Engineering

The course will introduce three basic building blocks of microwave engineering viz. microwave transmission system, passive circuit components at microwave frequency and microwave active devices. The lectures would try to emphasize the need to understand the blocks in somewhat detail so that key design concepts behind a microwave network are grasped. The course would lay the foundation for further exploring the vast area of microwave engineering analysis and design.

#### **Prerequisites**

Basic Knowledge of Electromagnetic Theory, Transmission line, Electronic network theory.

**Course Objectives:**

Upon completion of this course, students will be able to do the following:

•Understand fundamental electrical characteristics of waveguides and transmission lines through electromagnetic field analysis. |

•Understand the basic properties of Polarization and Ferrite materials composition in the case of waveguide components. |

•Understand the multiport junction concept for splitting the microwave energy in a desired direction. |

•Understand the function, design, and integration of the major microwave components like oscillator, modulator, power amplifier, filter, and mixer in building a Microwave test bench setup for measurements. |

**Course Outcomes:**

After completing this course the candidate should be able to:

•After going through this course the student will Gain knowledge of transmissionlines and waveguide structures and how they are used as elements in impedance matching and filter circuits. |

•Apply analysis methods to determine circuit properties of passive or active microwave devices. |

•Gain knowledge and understanding of microwave analysis methods. Distinguish between M-type and O-type tubes |

•Analyze and measure various microwave parameters using a Microwave test bench. |

**Syllabus**

### Unit 1

**MICROWAVE TRANSMISSION LINES:** Introduction, Microwave
Spectrum and Bands, Applications of Microwaves. Rectangular Waveguides
– TE/TM mode analysis, Expressions for Fields, Characteristic Equation and
Cut-off 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; Power Transmission and Power Losses in Rectangular Guide,
Impossibility of TEM mode. Related Problems.

### Unit 2

**CIRCULAR WAVEGUIDES:** Introduction, Nature of Fields,
Characteristic Equation, Dominant and Degenerate Modes. Microstrip Lines–
I ntroduction, Zo Relations, Effective Dielectric Constant, Losses, Q factor.
Cavity Resonators– Introduction, Rectangular and Cylindrical Cavities,
Dominant Modes and Resonant Frequencies, Q factor and Coupling
Coefficients, Excitation techniques- waveguides and cavities, Related
Problems.

### Unit 3

**WAVEGUIDE COMPONENTS AND APPLICATIONS - I :** Coupling
Mechanisms – Probe, Loop, Aperture types. Waveguide Discontinuities – Waveguide irises, Tuning Screws and Posts, Matched Loads. Waveguide
Attenuators – Resistive Card, Rotary Vane types; Waveguide Phase Shifters
– Dielectric, Rotary Vane types. Scattering Matrix– Significance,
Formulation and Properties. S-Matrix Calculations for – 2 port Junction, Eplane
and H-plane Tees, Magic Tee, Hybrid Ring; Directional Couplers –
2Hole, Bethe Hole types, Ferrite Components– Faraday Rotation, S-Matrix
Calculations for Gyrator, Isolator, Circulator, Related Problems.

### Unit 4

**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,
Applegate Diagram and Principle of working, Mathematical Theory of
Bunching, Power Output, Efficiency, Electronic Admittance; Oscillating
Modes and o/p Characteristics, Electronic and Mechanical Tuning, Related
Problems.

### Unit 5

**HELIX TWTS:** Significance, Types and Characteristics of Slow Wave
Structures; Structure of TWT and
Suppression of Oscillations, Nature of the four Propagation Constants.
M-type Tubes
Introduction, Cross-field effects, Magnetrons – Different Types, 8-Cavity
Cylindrical Travelling Wave
Magnetron – Hull Cut-off and Hartree Conditions, Modes of Resonance and
PI-Mode Operation, Separation of PI-Mode, o/p characteristics.

### Unit 6

**MICROWAVE SOLID STATE DEVICES:** Introduction, Classification,
Applications. TEDs – Introduction, Gunn Diode – Principle, RWH Theory,
Characteristics, Basic Modes of Operation, Oscillation Modes. Avalanche
Transit Time Devices – Introduction, IMPATT and TRAPATT Diodes –
Principle of Operation and Characteristics.

**MICROWAVE MEASUREMENTS:** Description of Microwave Bench –
Different Blocks and their Features, Precautions; Microwave Power
Measurement – Bolometer Method. Measurement of Attenuation, Frequency,
VSWR, Cavity Q. Impedance Measurements.