GATE ECE

Antennas

Electromagnetics

(Past Years Questions)

Marks 1

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The directivity of an antenna array can be increased by adding more antenna elements, as a larger number of elements
GATE ECE 2015 Set 3
For an antenna radiating in free space, the electric field at a distance of 1 km is found to be 12 m V/m. Given that int...
GATE ECE 2014 Set 4
Match column A with column B. Column 1. Point electromagnetic source 2. Dish antenna 3. Yagi-Uda antenna Colum...
GATE ECE 2014 Set 4
The radiation pattern of an antenna in spherical co-ordinates is given by $$$F\,(\theta )\, = {\cos ^4}\,\theta \,\,\,;\...
GATE ECE 2012
For a Hertz dipole antenna, the half power beam width (HPBW) in the E-plane is
GATE ECE 2008
A transmission line is feeding 1 Watt of power to a horn antenna having gain of 10 dB. The antenna is matched to the tra...
GATE ECE 2006
Refractive index of glass is 1.5. Find the wavelength of a beam of light with a frequency of $${10^{14}}$$ Hz in glass. ...
GATE ECE 2005
Consider a lossless antenna with a directive gain of + 6 dB. If 1 m W of power is fed to it the total power radiated by ...
GATE ECE 2004
The line-of-sight communication requires the transmit and receive antennas to face each other. If the transmit antenna i...
GATE ECE 2002
If the diameter of a $$\lambda /2$$ dipole antenna is increased from $$\lambda /100$$ to $$\lambda /50$$ then is
GATE ECE 2000
The radiation resistance of a circular loop of one turn is 0.01 $$\Omega $$. The radiation resistance of five turns of s...
GATE ECE 1998
An antenna in free space receives 2$$\mu $$ W of power when the incident electric field is 20 m V/m rms. The effective a...
GATE ECE 1998
The far field of an antenna varies with distance r as
GATE ECE 1998
The vector $$\mathop H\limits^ \to $$ in the far field of an antenna satisfiels
GATE ECE 1998
An antenna when radiating, has a highly directional radiation pattern. When the antenna is receiving its radiation patte...
GATE ECE 1995
For a dipole antenna
GATE ECE 1994

Marks 2

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A half wavelength dipole is kept in the x-y plane and oriented along $${45^ \circ }$$ from the x-axis. Determine the dir...
GATE ECE 2017 Set 1
An antenna pointing in a certain direction has a noise temperature of $$50K$$. The ambient temperature is $$290K$$. The ...
GATE ECE 2016 Set 1
Two lossless X-band horn antennas are separated by a distance of $$200\lambda $$. The amplitude reflection coefficients ...
GATE ECE 2016 Set 1
The far-zone power density radiated by a helical antenna is approximated as: $$$\overrightarrow W {\,_{rad}} = \overrigh...
GATE ECE 2016 Set 1
Two half-wave dipole antennas placed as shown in the figure are excited with sinusoidally varying currents of frequency ...
GATE ECE 2015 Set 2
At 20 GHz, the gain of a parabolic dish antenna of 1 meter diameter and 70% efficiency is
GATE ECE 2008
A $$\lambda /2$$ dipole is kept horizontally at a height of $${\lambda _0}/2$$ above a perfectly conducting infinite gro...
GATE ECE 2007
A mast antenna consisting of a 50 meter long vertical conductor operates over a perfectly conducting ground plane. It is...
GATE ECE 2006
Two identical and parallel dipole antennas are kept apart by a distance $$\lambda /4$$ of in the H-plane. They are fed w...
GATE ECE 2005
Two identical antennas are placed in the $$\theta = \pi /2$$ plane as shown in figure. The elements have equal amplitud...
GATE ECE 2003
A person with a receiver is 5 Km away from the transmitter. What is the distance that this person must move further to d...
GATE ECE 2002
A medium wave radio transmitter operating at a wavelength of 492 m has a tower antenna of height 124m. What is the radia...
GATE ECE 2001
In a uniform linear array, four isotropic radiating elements are spaced $$\lambda /4$$ apart. The progressive phase shif...
GATE ECE 2001
For an 8 feet (2.4 m) parabolic disk antenna operating at 4 GHz, the minimum distance required for far field measurement...
GATE ECE 2000
The half-power beam widths (HPBW) of an antenna in the two orthogonal planes are $${100^ \circ }$$ and $${60^ \circ }$$...
GATE ECE 2000
A transmitting antenna radiates 251 W isotropically. A receiving antenna, located 100m away from the transmitting antenn...
GATE ECE 1999
A parabolic dish antenna has a conical beam 20 wide. The directivity of the antenna is approximately
GATE ECE 1997
A transverse electromagnetic wave with circular polarization is received by a dipole antenna. Due to polarization mismat...
GATE ECE 1996
A 1 km long microwave link uses two antennas each having 30dB gain. If the power transmitted by one antenna is 1 W at 3 ...
GATE ECE 1996
Two dissimilar antennas having their maximum directivities equal
GATE ECE 1992
The beam width-between-first-null of a uniform linear array of N equally-spaced (element spacing = d) equally-excited an...
GATE ECE 1992
In a board side array of 20 isotropic radiators, equally spaced at a distance of $$\lambda /2$$, the veam width between ...
GATE ECE 1991
Two isotropic antennas are separated by a distance of two wavelengths. If both the antennas are fed with currents of equ...
GATE ECE 1990
In the case of ground wave propagation, at far-off distances from the transmitting tower antenna, the Poynting vector is...
GATE ECE 1989
The electric field E and the magnetic field H of a short dipole antenna satisfy the condition
GATE ECE 1988

Marks 4

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A thin dipole antenna is $$\left( {\lambda /15} \right)$$ long, where $$\lambda $$ is the voperating wavelength. If the ...
GATE ECE 1987

Marks 5

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Consider a linear array of two half - wave dipoles A and B as shown in Fig. The dipoles are $${\lambda \over 4}$$ apart...
GATE ECE 2002
The average power of an omni-directional antenna varies as the magnitude of cos($$\theta $$) where $$\theta $$ is the az...
GATE ECE 1999
A dipole antenna has a sin$$\theta $$ radiation pattern where the angle $$\theta $$ is measured from the axis of the dip...
GATE ECE 1997
Two isotropic antennas A and B from an array as shown in Fig. The currents fed to the two antennas are $${{\rm I}_0}\,\a...
GATE ECE 1996
Two dipoles are so fed and oriented in free space that they produce the following electromagnetic waves: $$${E_x} = 10\...
GATE ECE 1995
Two spacecrafts are separated by 3000 km. Each has a paraboloidal reflector antenna of 0.85 m diameter operating at a fr...
GATE ECE 1994
Consider an array of two non-directional radiators with spacing $$d\,\, = \,\,0.5\,\,\lambda $$. Determine the direction...
GATE ECE 1993

Marks 8

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Elements of a linear array of three equally spaced (element spacing $$0.5\lambda $$ ) vertical mast radiators are excite...
GATE ECE 1992

Marks 10

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In the radiation pattern of a 3-element array of isotropic radiators equally spaced at distances of $${\lambda /4}$$ it...
GATE ECE 1991
Two vertically oriented half wave dipoles are spaced 1.5 wavelengths apart to from an array. Calculate the half power be...
GATE ECE 1989

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