1
GATE ECE 1990
MCQ (More than One Correct Answer)
+2
-0.6
Choose the correct statements.
For a wave propagating in an air filled rectangular wave guide
A
Guided wavelength is never less than the free space wavelength
B
Wave impedance is never less than the free space impedance.
C
Phase velocity is never less than the free space velocity
D
TEM mode is possible if the dimensions of the wave guide are properly chosen.
2
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 $$\varepsilon = {1 \over {36\pi }} \times {10^{ - 9}}$$ $$F/m$$

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
MCQ (Single Correct Answer)
+1
-0.3
In a junction diode
A
The depletion capacitance increases with increase in the reverse bias
B
The depletion capacitance decreases with increase in the reverse bias
C
The depletion capacitance increases with increase in the forward bias
D
The depletion capacitance is much higher than the depletion capacitance when it is forward bias.
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