Microwave Engineering (EC-702 (A)) - Important Questions

Derive the expressions for effective dielectric constant and characteristic impedance of a microstrip line and discuss the effect of strip width and substrate height.

Explain the dominant and higher-order modes in stripline structure.

Explain the structure, principle of operation, and electron beam-RF field interaction mechanism in a TWT amplifier with neat sketch.

Draw the structure and explain the working principle / velocity modulation process of a two-cavity klystron amplifier and its applications.

Explain the construction and working of a reflex klystron including its mode curve/characteristics.

Explain the Gunn effect, bulk properties giving negative resistance, domains of operation of a Gunn diode and its use as Gunn oscillator.

Explain the working principle and characteristics of a Schottky barrier diode. Discuss its use as a microwave mixer and detector.

Describe the working of a microwave BJT, its frequency limitations and applications.

Define scattering matrix. State and explain its properties for a reciprocal network and derive the general form for a reciprocal and lossless two-port microwave network.

Explain the construction and working of a Slotted Line. How is it used to determine VSWR, wavelength and impedance?

Explain the methods for measurement of microwave frequency and VSWR. Describe the working of a VSWR meter with suitable example.

What is a magic Tee (matched hybrid Tee) junction? Derive its scattering matrix, showing how it combines E-plane and H-plane tee properties.

What are directional couplers? Explain their basic derived parameters such as coupling, directivity, isolation and insertion loss.

Describe the design and working of single-section and multi-section impedance transformers and explain how multi-section design increases bandwidth.

Write short notes on any two: (i) Working principle of microwave mixer, roles of LO, RF and IF signals and conversion loss (ii) Block diagram of frequency converters using varactor diodes (iii) Design of RF/microwave oscillator using S-parameter techniques (iv) Diode phase shifters.