1

GATE ECE 2017 Set 1

MCQ (Single Correct Answer)

+2

-0.6

A half wavelength dipole is kept in the x-y plane and oriented along $${45^ \circ }$$ from the x-axis. Determine the direction of null in the radiation pattern for $$0 \le \phi \le \pi $$. Here the angle $$\theta \left( {0 \le \theta \le \pi } \right)$$ is measured from the z-axis, and the angle $$\phi \left( {0 \le \phi \le 2\pi } \right)$$ is measured from the x-axis in the x-y plane.

2

GATE ECE 2016 Set 1

MCQ (Single Correct Answer)

+2

-0.6

An antenna pointing in a certain direction has a noise temperature of $$50K$$. The ambient temperature is $$290K$$. The antenna is connected to a pre-amplifier that has a noise figure of 2 dB and an available gain of 40 dB over an effective bandwidth of $$12$$ $$MHz$$. The effective input noise temperature $${T_e}$$ for the amplifier and the noise power $${P_{ao}}$$ at the output of the preamplifier, respectively, are

3

GATE ECE 2016 Set 1

Numerical

+2

-0

Two lossless X-band horn antennas are separated by a distance of $$200\lambda $$. The amplitude reflection coefficients at the terminals of the transmitting and receiving antennas are $$0.15$$ and $$0.18$$, respectively. The maximum directivities of the transmitting and receiving antennas (over the isotropic antenna) are $$18$$ $$dB$$ and $$22$$ $$dB$$, respectively. Assuming that the input power in the lossless transmission line connected to the antenna is $$2$$ $$W$$, and that the antennas are perfectly aligned and polarization matched, the power ( in mW) delivered to the load at the receiver is ________ .

Your input ____

4

GATE ECE 2016 Set 1

MCQ (Single Correct Answer)

+2

-0.6

The far-zone power density radiated by a helical antenna is approximated as:
$$$\overrightarrow W {\,_{rad}} = \overrightarrow W \,average\, \approx \,\widehat a{}_rC{}_0\,{1 \over {{r^2}}}{\cos ^4}\theta $$$

The radiated power density is symmetrical with respect to $$\phi $$ and exists only in the upper hemisphere: $$0 \le \theta \le {\pi \over 2};\,\,\,\,0 \le \theta \le 2\pi ;$$

$${C_0}$$ is a constant. The power radiated by the antenna (in watts) and the maximum directivity of the antenna, respectively, are

Questions Asked from Antennas (Marks 2)

Number in Brackets after Paper Indicates No. of Questions

GATE ECE 2017 Set 1 (1)
GATE ECE 2016 Set 1 (3)
GATE ECE 2015 Set 2 (1)
GATE ECE 2008 (1)
GATE ECE 2007 (1)
GATE ECE 2006 (1)
GATE ECE 2005 (1)
GATE ECE 2003 (1)
GATE ECE 2002 (1)
GATE ECE 2001 (2)
GATE ECE 2000 (2)
GATE ECE 1999 (1)
GATE ECE 1997 (1)
GATE ECE 1996 (2)
GATE ECE 1992 (2)
GATE ECE 1991 (1)
GATE ECE 1990 (1)
GATE ECE 1989 (1)
GATE ECE 1988 (1)

GATE ECE Subjects

Signals and Systems

Representation of Continuous Time Signal Fourier Series
Discrete Time Signal Fourier Series Fourier Transform
Discrete Time Signal Z Transform
Continuous Time Linear Invariant System
Transmission of Signal Through Continuous Time LTI Systems
Discrete Time Linear Time Invariant Systems
Sampling
Continuous Time Signal Laplace Transform
Discrete Fourier Transform and Fast Fourier Transform
Transmission of Signal Through Discrete Time Lti Systems
Miscellaneous
Fourier Transform

Network Theory

Control Systems

Digital Circuits

General Aptitude

Electronic Devices and VLSI

Analog Circuits

Engineering Mathematics

Microprocessors

Communications

Electromagnetics