B.TECH - Semester 6 antenna and wave propagation Question Paper 2020 (jan)
Practice authentic previous year university questions for better exam preparation.
Sample Questions
- With necessary equations explain the terms wave polarization and antenna temperature.
- Explain the concept of retarded potential.
- Discuss grating lobes.
- Explain type of antenna suitable for mobile hand sets.
- Discuss the principle of beam steering.
- Explain uniform linear arrays.
- Discuss the term diversity in the context of wave propagation.
- What is MUF?
- Calculate the radiation resistance of $\lambda / 2$ wire dipole in free space.
- Discuss the features of log periodic antenna. ( $\mathbf{1 0} \boldsymbol{\times} \mathbf{2} \boldsymbol{=} \mathbf{2 0}$ Marks) P.T.O. Answer any one question from each module. Each question carries 20 marks.
- (a) A transmitting antenna with a directivity of 30 dBi takes an input power of 12 kW and its efficiency is $85 \% \mathrm{~W}$. Find the maximum possible power density at a distance of 5 km from it.
- (b) If the input power to an antenna is 1.8 kW with a radiation efficiency of $95 \%$. Find radiated and dissipated power.
- Write short notes on: (a) radiation efficiency (b) radiation resistance (c) effective height (d) effective aperature (e) capture area.
- (a) Derive the expression of field pattern in the case of two isotropic point sources of same amplitude and unequal phase separated by a distance ' $d$ '.
- (b) State and explain the Principle of pattern multiplication. Illustrate this principle with an N element array.
- (a) Design a broadside Dolph - Tschebyscheff array of 8 elements with spacing of $d=\lambda / 2$ between the element and major to minor lobe ratio of 25 dB .
- (b) Using the Principle of Pattern multiplication obtain the radiation pattern of four element binomial array with spacing of $d=\lambda / 2$.
- (a) A right handed monofilar helical antenna has 15 turns, 100 mm diameter and 60 mm turn spacing. The frequency is 1.2 GHz . Find out: (i) HPBW (ii) Gain (iii) State of Polarization.
- (b) Design a rectangular microstrip antenna using a substrate with a dielectric constant of 2.25 and operating at 12 GHz . Take Height of Substrate $(\mathrm{h}=0.12 \mathrm{~cm})$.
- (a) Explain the construction and working of Rhombic Antenna and $\vee$ Antenna.
- (b) With the help of neat diagrams explain the principle of operation of Log Periodic Antenna.
- (a) Explain Tropospheric scatter propagation.
- (b) Derive an expression for the LOS distance in km when the antenna heights above ground are $h_{t}$ and $h_{r}$ respectively for the transmitter and receiver.
- (a) Explain the various diversity techniques used in wave propagation.
- (b) Explain the terms: Duct propagation, Virtual height skip distance. $$ (4 \times 20=80 \text { Marks }) . $$