JNTU
JNTU B.Tech III ANTENNAS AND WAVE PROPAGATION Previous Question Paper (August/September - 2024 - R13)
Note: i) Question paper consists of Part A, Part B.
ii) Part A is compulsory, which carries 25 marks. In Part A, Answer all questions.
iii) In Part B, Answer any one question from each unit. Each question carries 10 marks and may have a, b as sub questions.
Part A
Distinguish power gain and directive gain.
Answer
Directive gain is defined as the ratio of the radiation intensity in a given direction to the radiation intensity averaged over all directions, representing how well an antenna concentrates energy in a specific direction regardless of efficiency. Power gain, however, accounts for the antenna's efficiency by multiplying the directive gain by the radiation efficiency factor, representing the actual power radiated in a specific direction relative to the total power input to the antenna.
where G is power gain, D is directive gain, and η is the radiation efficiency (0 ≤ η ≤ 1).
The field amplitude due to half wave dipole in 10Km is 0.1V/m and it operates at 100MHz. Find the dipole length.
Answer
The length of a half-wave dipole is determined by its operating frequency and is independent of the field amplitude or distance. For a half-wave dipole, the physical length L is approximately half the wavelength λ.
First, calculate the wavelength using the frequency f = 100 MHz (100 × 106 Hz) and the speed of light c ≈ 3 × 108 m/s:
The length of the half-wave dipole is:
Calculate the bandwidth of a 50cm long half wave dipole having a Q of 15?
Answer
Sign in to view the complete answer paper.
Write the salient features of Yagi-Uda antenna.
Answer
Sign in to view the complete answer paper.
A paraboloid reflector operates at 4GHz. Its mouth diameter is 6m. Find the minimum distance required far field pattern of paraboloid between two antennas.
Answer
Sign in to view the complete answer paper.
Write the Characteristics of Microstrip Antennas.
Answer
Sign in to view the complete answer paper.
Differentiate broadside array and end fire array.
Answer
Sign in to view the complete answer paper.
List the various antenna parameter measurement ranges. Also compare the features of outdoor and indoor ranges.
Answer
Sign in to view the complete answer paper.
Determine the critical frequency of EM wave for D (N=400electrons/cm3), E (N=5×105 electrons/cm3) and F (N=2×106 electrons/cm3) layers.
Answer
Sign in to view the complete answer paper.
Write the relation between MUF and Skip Distance.
Answer
Sign in to view the complete answer paper.
Part B
Derive an expression for field components present due to a small current element.
Answer
Sign in to view the complete answer paper.
A thin dipole antenna is λ/15 long. If its radiation loss is 1.5Ω, find the radiation resistance and efficiency of an antenna.
Answer
Sign in to view the complete answer paper.
Explain the antenna radiation intensity and power density.
Answer
Sign in to view the complete answer paper.
Write the design and far field equations for helical antenna.
Answer
Sign in to view the complete answer paper.
Calculate the directivity (in dB) of a helical antenna which has 50 turns, λ/3 diameter and λ/5 turn spacing. The helix is right handed.
Answer
Sign in to view the complete answer paper.
Explain in detail about Horn antenna and its types.
Answer
Sign in to view the complete answer paper.
Describe various methods used for feeding a parabolic reflector.
Answer
Sign in to view the complete answer paper.
Discuss the working of lens antenna.
Answer
Sign in to view the complete answer paper.
What is the need of binomial array? Explain the general considerations of it.
Answer
Sign in to view the complete answer paper.
Write the principle of pattern multiplications.
Answer
Sign in to view the complete answer paper.
Illustrate the measurement methods of antenna pattern and directivity.
Answer
Sign in to view the complete answer paper.
Explain in detail about the structure of atmosphere for communication point of view.
Answer
Sign in to view the complete answer paper.
Explain the concept of Super Refraction.
Answer
Sign in to view the complete answer paper.
Write short notes on ionosphere abnormalities.
Answer
Sign in to view the complete answer paper.