1
GATE ECE 1999
Subjective
+5
-0
The average power of an omni-directional antenna varies as the magnitude of cos($$\theta$$) where $$\theta$$ is the azimuthal angle. Calculate the maximum Directive Gain of the antenna and the angles at which it occurs.
2
GATE ECE 1997
Subjective
+5
-0
A dipole antenna has a sin$$\theta$$ radiation pattern where the angle $$\theta$$ is measured from the axis of the dipole. The dipole is vertically located above an ideal ground plane (Fig.). What should be the height of the dipole H in terms of wave length so as to get a null in the radiation pattern at an angle of 450 from the ground plane? Find the direction of maximum radiation also. 3
GATE ECE 1996
Subjective
+5
-0
Two isotropic antennas A and B from an array as shown in Fig. The currents fed to the two antennas are $${{\rm I}_0}\,\angle 0$$ and $${{\rm I}_0}\,\angle \alpha$$ respectively. What should be the value of $$\alpha$$ so that the radiation pattern has a null at $$\theta = {30^ \circ }$$. Find the direction of the maximum radiation for that value of $$\alpha$$ and draw the radiation pattern. ($$\lambda \,\,$$ is the wavelength of operation) 4
GATE ECE 1995
Subjective
+5
-0
Two dipoles are so fed and oriented in free space that they produce the following electromagnetic waves: $${E_x} = 10\,{e^{j\left( {\omega t - z\pi /3} \right)}}\,\,volts/metre$$$$${E_y} = j\,\,10\,{e^{j\left( {\omega t - z\pi /3} \right)}}\,\,volts/metre$$$

(a) Write down the expression for the corresponding magnetic field strength vector.
(b) Calculate the frequency of the wave.
(C) Give the complete description of the polarization of the wave.

GATE ECE Subjects
Signals and Systems
Network Theory
Control Systems
Digital Circuits
General Aptitude
Electronic Devices and VLSI
Analog Circuits
Engineering Mathematics
Microprocessors
Communications
Electromagnetics
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