RF Modelling And Antennas Question Paper - Dec 17 - Electronics And Telecomm (Semester 5)

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RF Modelling And Antennas - Dec 17

Electronics And Telecomm (Semester 5)

Total marks: 80
Total time: 3 Hours INSTRUCTIONS
(1) Question 1 is compulsory.
(2) Attempt any three from the remaining questions.
(3) Draw neat diagrams wherever necessary.

Q1. Attempt any four out of the remaining five

1.a. Explain hazards of electromagnetic radiation.

(5 marks)

1.b. Explain how Richard's transformation and unit elements are useful in RF filters designing.

(5 marks)

1.c. Explain near field, inductive field and radiation field related to antenna.

(5 marks)

1.d. Explain pattern multiplication for antenna array.

(5 marks)

1.e. What are characteristics of Horn antenna?

(5 marks)

2.a. Design a low pass composite filter with cut-off frequency 3 MHz and impedance of 75$\Omega$. Place infinite attenuation pole at 3.08 MHz.

(10 marks)

2.b.. Explain with equivalent circuits the RF behaviour of resistor, capacitor and inductor.

(10 marks)

3.a. Design a maximally flat low pass filter with a cut-off frequency of 2 GHz, impedance of 50$\Omega$, and at least 15 dB insertion loss at 3GHz.

(10 marks)

3.b. Explain in detail dipole antenna . Compare dipole, monopole and folded dipole antennas.

(10 marks)

4.a. Derive radiation resistance of infinitesimal dipole.

(10 marks)

4.b. Find the radiation pattern of an array of 2 isotropic point sources fed with same amplitude and opposite phase and spaced $\lambda / 2$ apart. Find its HPBW and FNBW.

(10 marks)

5.a. Explain working principle of Yagi-Uda antenna and draw its radiation pattern. Mention its applications.

(10 marks)

5.b. Draw the structure of microstrip antenna. Discuss its characteristics, limitations and applications.

(10 marks)

Write short notes on the following

6.a. Friss transmission formula

(5 marks)

6.b. Log periodic antenna

(5 marks) 00

6.c. Helical antenna

(5 marks) 00

6.d. Principal of parabolic reflector antenna

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(5 marks) 00

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