EC GATE 2007 - Online Test
Q1. A load of 50 Ω is connected in shunt in a 2-wire transmission line of Z0 = 50Ω as shown in the figure. The 2-port scattering parameter matrix (s-matrix) of the
shunt element is
Answer : Option C
Explaination / Solution:
Q2. The parallel branches of a 2-wire transmission line re terminated in 100Ω and
200Ω resistors as shown in the figure. The characteristic impedance of the
line is Z0 = Ω and each section has a length of λ/4. The voltage reflection
coefficient Γ at the input is
Answer : Option D
Explaination / Solution:
Q3. A λ/2 dipole is kept horizontally at a height of λ0/2 above a perfectly conducting
infinite ground plane. The radiation pattern in the lane of the dipole (
plane)
looks approximately as
plane)
looks approximately as
Answer : Option B
Explaination / Solution:
Q4. A right circularly polarized (RCP) plane wave is incident at an angle 600 to the
normal, on an air-dielectric interface. If the reflected wave is linearly polarized,
the relative dielectric constant ξr is.
Answer : Option D
Explaination / Solution:
No Explaination.
Q5. Two 4-array signal constellations are shown. It is given that φ1 and φ2 constitute
an orthonormal basis for the two constellation. Assume that the four symbols
in both the constellations are equiprobable. Let N0/2 denote the power spectral
density of white Gaussian noise.
The if ratio or the average energy of Constellation 1 to the average energy of
Constellation 2 is
Answer : Option B
Explaination / Solution:
Q6. In a transconductance amplifier, it is desirable to have
Answer : Option A
Explaination / Solution:
In the transconductance amplifier it is desirable to have large input resistance and large output resistance.
Q7. If C is code curve enclosing a surface S , then magnetic field intensity 
, the
current density 
and the electric flux density 
are related by
, the
current density and the electric flux density are related by
Answer : Option D
Explaination / Solution:
Q8. For the Op-Amp circuit shown in the figure, V is
Answer : Option C
Explaination / Solution:
No Explaination.
Q9. Two 4-array signal constellations are shown. It is given that φ1 and φ2 constitute an orthonormal basis for the two constellation. Assume that the four symbols in both the constellations are equiprobable. Let N0/2 denote the power spectral density of white Gaussian noise.
If these constellations are used for digital communications over an AWGN channel, then which of the following statements is true ?
Answer : Option A
Explaination / Solution:
No Explaination.
Q10. It is given that X, X .... XM at M non-zero, orthogonal vectors. The dimension of
the vector space spanned by the 2M vectors X, X, ....XM, - X, - X, ..... - XM is
Answer : Option C
Explaination / Solution:
For two orthogonal vectors, we require two dimensions to define them and similarly for three orthogonal vector we require three dimensions to define them. 2M vectors are basically M orthogonal vector and we require M dimensions to define them.
