1
GATE ECE 2002
Subjective
+5
-0
Consider a linear array of two half - wave dipoles A and B as shown in Fig. The dipoles are $${\lambda \over 4}$$ apart and are excited in such a way that the current on element B lags that on element A by $${90^0}$$ in phase

(a) Obtain the expression for the radiation pattern for E in the XY plane, i.e.,$$\left( {\theta = {{90}^0}} \right)$$.
(b) Sketch the radiation pattern obtained in (a). 2
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.
3
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. 4
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) 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
EXAM MAP
Joint Entrance Examination