1
GATE ECE 1990
MCQ (Single Correct Answer)
+1
-0.3
The minimum function that can detect a "divisible by 3" 8421 BCD code digit (representation is D8 D4 D2 D1) is given by:
A
$${D_8}\,{D_1}\, + {D_4}\,{D_2}\, + \,\overline {{D_8}} \,{D_2}\,{D_1}$$
B
$${D_8}\,{D_1}\, + {D_4}\,{D_2}\,\overline {{D_1}} \, + \,\overline {{D_4}} \,{D_2}{D_1} + \overline {{D_8}} \,\overline {{D_4}} \,\overline {{D_2}} \,\overline {{D_1}} \,$$
C
$${D_8}\,{D_1}\, + \,{D_4}\,{D_2}\, + \,\overline {{D_8}} \,\overline {{D_4}} \,\overline {{D_2}} \,\overline {{D_1}} \,$$
D
$${D_4}\,{D_2}\,\overline {{D_1}} \, + \,{D_4}\,{D_2}\,{D_1}\, + \,{D_8}\,\overline {{D_4}} \,{D_2}{D_1}$$
2
GATE ECE 1990
MCQ (Single Correct Answer)
+1
-0.3
The number of Boolean functions that can be generated by n variable is equal to:
A
2$$^n$$
B
$${2^2}^n$$
C
2$$^{n - 1}$$
D
2$$^{n + 1}$$
3
GATE ECE 1990
MCQ (Single Correct Answer)
+2
-0.6
Two isotropic antennas are separated by a distance of two wavelengths. If both the antennas are fed with currents of equal phase and magnitude, the number of lobes in the radiation pattern in the horizontal plane are
A
2
B
4
C
6
D
8
4
GATE ECE 1990
Subjective
+8
-0
A 300 MHz plane E.M. wave is propagating in free space. The wave is incident normally on an infinite copper slab. For the transmitted wave in the copper slab, calculate the following

(a) Attenuation constant
(b) Phase constant
(c) Skin depth
(d) Phase velocity and
(e) Group velocity

for copper assume the following values
Conductivity $$\sigma = 5.8 \times {10^7}$$ $$mho/m$$
Permeability $$\mu = 4\pi \times {10^{ - 7}}$$ $$H/m$$
Permeability $$\varepsilon = {1 \over {36\pi }} \times {10^{ - 9}}$$ $$F/m$$

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