# A message signal given by m(t) = (1/2) cos ω1t - (1/2) sin ω2t. Is amplitude modulated with a carrier of frequency ωc to generate s(t) = [1 + m(t)] cos ωct

1.  8.33%

2.  11.11%

3.  20%

4.  25%

4

20\%

Explanation :
No Explanation available for this question

# For the circuit shown in the figure, D has a transition from 0 to 1 after CLK changes from 1 to 0. Assume gate delays to be negligible Which of the following statements is true

1.  Q goes to 1 at the CLK transition and stays at 1.

2.  Q goes to 0 at the CLK transition and stays at 0

3.  Q goes to 1 at the CLK transition and goes to 0 when D goes to 1.

4.  Q goes to 0 at the CLK transition and goes to 1 when D goes to 1

4

Q goes to 1 at the CLK transition and goes to 0 when D goes to 1.

Explanation :
No Explanation available for this question

# A  communication  channel with  AWGN  operating  at  a  signal  to  noise  ratio  SNR>>1  and bandwidth  B  has  capacity  C1.  If  the  SNR  is  doubled  keeping  B  constant,  the  resulting capacity C2 is given by

1.  C2 ≈ 2C1

2.  C2 ≈ C1 + B

3.  C2 ≈ C1 + 2B

4.  C2 ≈ C1 + 0.3B

4

C2 ≈ C1 + B

Explanation :
No Explanation available for this question

# A rectangular waveguide of internal dimensions (a = 4 cm and b = 3 cm) is to be operated in TE11 mode. The minimum operating frequency is

1.   6.25 GHz

2.  6.0 GHz

3.  5.0 GHz

4.  3.75 GHz

4

6.25 GHz

Explanation :
No Explanation available for this question

# One end of a  loss-less  transmission  line having  the characteristic  impedance of 75 and length  of  1  cm  is  short-circuited. At  3 GHz,  the  input  impedance  at  the  other  end  of  the transmission line is

1.  0

2.  Resistive

3.  Capacitive

4.  Inductive

4

Inductive

Explanation :
No Explanation available for this question

# A uniform plane wave  in  the  free space  is normally  incident on an  infinitely  thick dielectric slab (dielectric constant ε = 9). The magnitude of the reflection coefficient is

1.  0

2.  0.3

3.  0.5

4.  0.8

4

0.5

Explanation :
No Explanation available for this question

# A magnetic field in air is measured to be B = B0 ((x/(x2 + y2))  - (y/(x2 + y2)) ). What  current    distribution  leads  to  this  field  [Hint:  The  algebra  is  trivial  in  cylindrical coordinates.]

1.  = (B0 /μ0)(1/(x2 + y2))

2.  = (B0 /μ0)(2/(x2 + y2))

3.  = 0, r ≠ 0

4.  = (B0 /μ0)(3/(x2 + y2)),

4 = 0, r ≠ 0

Explanation :
No Explanation available for this question

# In  the design of a  single mode  step  index optical  fiber  close  to upper  cut-off,  the  single-mode operation is NOT preserved if

1.  radius as well as operating wavelength are halved

2.  radius as well as operating wavelength are doubled

3.  radius is halved and operating wavelength is doubled

4.  radius is doubled and operating wavelength is halved

4

radius is doubled and operating wavelength is halved

Explanation :
No Explanation available for this question

# At 20 GHz, the gain of a parabolic dish antenna of 1 meter diameter and 70% efficiency is

1.  15 dB

2.  25 dB

3.  35 dB

4.  45 dB

4

45 dB

Explanation :
No Explanation available for this question

1.  200

2.  100?

3.  50?

4.  25?

4