1
GATE ECE 2005
+2
-0.6
Two identical and parallel dipole antennas are kept apart by a distance $$\lambda /4$$ of in the H-plane. They are fed with equal currents but the right most antenna has a phase shift of +90°. The radiation pattern is given as
A
B
C
D
2
GATE ECE 2003
+2
-0.6
Two identical antennas are placed in the $$\theta = \pi /2$$ plane as shown in figure. The elements have equal amplitude excitation with 180° polarity difference, operating at wavelength λ. The correct value of the magnitude of the far zone resultant electric field strength normalized with that of a single element, both computed for $$\phi = 0$$ is
A
$$2\,\cos \left( {{{2\,\pi s} \over \lambda }} \right)$$
B
$$2\,\sin \left( {{{2\,\pi s} \over \lambda }} \right)$$
C
$$2\,\cos \left( {{{\pi s} \over \lambda }} \right)$$
D
$$2\,\sin \left( {{{\pi s} \over \lambda }} \right)$$
3
GATE ECE 2002
+2
-0.6
A person with a receiver is 5 Km away from the transmitter. What is the distance that this person must move further to detect a 3-dB decrease in signal strength?
A
942 m
B
2070 m
C
4978 m
D
5320 m
4
GATE ECE 2001
+2
-0.6
In a uniform linear array, four isotropic radiating elements are spaced $$\lambda /4$$ apart. The progressive phase shift between the elements required for forming the main beam at 60° off the end-fire is
A
$$- \pi \,\,rad$$
B
$$- \pi /2\,\,rad$$
C
$$- \pi /4\,\,rad$$
D
$$- \pi /8\,\,rad$$
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