STUPIDSID
1 (a)
Define the following terms with respect to antenna:
(i) Gam (ii) Isotropic radiator (iii) Beam area
(iv) Radiation resistance
(i) Gam (ii) Isotropic radiator (iii) Beam area
(iv) Radiation resistance
8 M
1 (b)
Prove that maximum effective aperture for a λ/2 antenna is 0.13λ2.
6 M
1 (c)
The effective apertures of transmitting and receiving antennas in a communication system are 8&lamba;2 and 12λ2 respectively, with a separation of 1.5 km between them. The E.M. wave is travelling with a frequency of 6 MHz and the total I/P power is 2.5 kW. Find the power received by the receiving antenna.
6 M
2 (a)
Derive an expression of power radiated from an isotropic point source with "sine squared power pattern". Also find directivity "D" and draw power pattern.
6 M
2 (b)
Find the power radiated and directivity for the unidirectional point source, having the following point source power patterns:
i) U=Um cos2 θ sin3 ϕ, 0?θ?Π, 0?ϕ?Π
ii) U=Um sin2 θ sin3ϕ, 0?θ?Π, 0?ϕ ? Π
i) U=Um cos
ii) U=Um sin2 θ sin3ϕ, 0?θ?Π, 0?ϕ ? Π
6 M
2 (c)
Eight point source are spaced λ/6 apart. They have a phase difference of Π/3 between adjacent element. Obtain the field pattern. Also find BWFN and HPBW
8 M
3 (a)
Show that the radiation resistance of a half wave \[ \left ( \dfrac {\lambda}{2} \right ) \] dipole antenna is 73Ω.
6 M
3 (b)
Write an explanatory note on folded dipole antenna, giving neat figures.
6 M
3 (c)
A magnetic field strength of 20 μA/m is required to be produced at a point 2.5 km from the antenna in the broadside plane, in space. How much power is transmitted by,
i) A hertz dipole with \[ l=\dfrac {\lambda}{15} \] ii) a half wave dipole and
iii) a monopole antenna.
i) A hertz dipole with \[ l=\dfrac {\lambda}{15} \] ii) a half wave dipole and
iii) a monopole antenna.
8 M
4 (a)
Discuss the features of a loop antenna. Derive an expression for the far field components of a loop antenna.
10 M
4 (b)
Explain Babinct's principle with illustrations. Discuss features of complementary antennas, with neat figures.
10 M
5 (a)
With a neat figure, explain the working of Yagi-Uda antenna. Write the design formulae for different components, used in Yagi-Uda antenna. Also mention the applications of Yagi-Uda antennas.
8 M
5 (b)
Determine:
i) The length L aperture 'an' and half angles in E and H planes for a pyramidal Horn antenna, for which aE=10λ. The horn is fed with a rectangular wave guide in TE10 mode. Let \[ \delta = \dfrac {\lambda}{12}\ in \ the \ E- plane \ and \ \delta=\dfrac {\lambda} {6} \] in the H-plane.
ii) Calculate directivity 'D'.
i) The length L aperture 'an' and half angles in E and H planes for a pyramidal Horn antenna, for which aE=10λ. The horn is fed with a rectangular wave guide in TE10 mode. Let \[ \delta = \dfrac {\lambda}{12}\ in \ the \ E- plane \ and \ \delta=\dfrac {\lambda} {6} \] in the H-plane.
ii) Calculate directivity 'D'.
8 M
6 (a)
Write note on:
i) Plasma antenna.
ii) Embedded antenna
i) Plasma antenna.
ii) Embedded antenna
8 M
6 (b)
With a neat sketch, explain the principle of lens antenna.
6 M
6 (c)
A parabola reflector of 2m diameter is used at 10 GHz. Calculate the beam width between first nulls (BWFN) HPBW and gain in dB.
6 M
7 (a)
Discuss various forms of radio-wave propagation.
8 M
7 (b)
Derive the expression for resultant electric field strength (ER) at a point, due to space wave propagation.
6 M
7 (c)
Derive the expression for 'Line of sight' distance (LOS) between transmitting and receiving antennas.
6 M
8 (a)
A high frequency radio link is to be established between two points on the earth 350 km apart. The reflection region of the atmosphere is at a height of 250 km and has a critical frequency of 8 MHz. Calculate the maximum usable frequency (MUF), for the given path in case of flat earth.
6 M
8 (b)
Define skip distance. Derive an expression for skip distance (D), for a flat earth.
6 M
8 (c)
Define critical frequency. Find the critical frequency for a particular ionospheric layer with Nm=9×106 /cm3. Also find maximum usable frequency (MUF), if the angle of incidence ∠i-60°.
8 M
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