If S(f) is the power spectral density of a real, wide-sense stationary random process, then which of the following is ALWAYS true?

**A. ** S(0)≤S(f)

**B. ** S(f)≥0

**C. ** S(-f) = -S(f)

**D. **

**Answer : ****Option B**

**Explaination / Solution: **

No Explaination.

No Explaination.

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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 Z_{0} = Ω and each section has a length of λ/4. The voltage reflection
coefficient Γ at the input is

**A. ** -j-

**B. ** -5/7

**C. ** j-

**D. ** 5/7

**Answer : ****Option D**

**Explaination / Solution: **

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A signal flow graph of a system is given below

**A. **

**B. **

**C. **

**D. **

**Answer : ****Option C**

**Explaination / Solution: **

The set of equalities that corresponds to this signal flow graph is

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The signal is

**A. ** FM only

**B. ** AM only

**C. ** both AM and FM

**D. ** neither AM nor FM

**Answer : ****Option C**

**Explaination / Solution: **

No Explaination.

No Explaination.

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The Nyquist sampling rate for the signal is given by

**A. ** 400 Hz

**B. ** 600 Hz

**C. ** 1200 Hz

**D. ** 1400 Hz

**Answer : ****Option C**

**Explaination / Solution: **

S(t) = sinc(500t) sinc(700t)

S(t) = sinc(500t) sinc(700t)

S(f ) is convolution of two signals whose spectrum covers f1 = 250 Hz and f2 = 350 Hz. So convolution extends

f = 25 + 350 = 600 Hz

Nyquist sampling rate

N = 2f = 2#600 = 1200 Hz

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A half wavelength dipole is kept in the x-y plane and oriented along 45^{0 }from the x-axis. Determine the direction of null in the radiation pattern for 0 ≤ ϕ ≤ π. Here the angle θ (0 ≤ θ ≤ π) is measured from the z-axis, and the angle ϕ (0 ≤ ϕ ≤ 2π) is measured from the x-axis in the x-y plane.
**A. ** θ = 90^{0}, ϕ= 45^{0}

**B. ** θ = 45^{0}, ϕ= 90^{0}

**C. ** θ = 90^{0}, ϕ= 135^{0}

**D. ** θ = 45^{0}, ϕ= 135^{0}

**Answer : ****Option A**

**Explaination / Solution: **

The null occurs along axis of the antenna which is θ = 90^{0}and ϕ= 45^{0}

The null occurs along axis of the antenna which is θ = 90

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The maximum value of ᶿ until which the approximation sin ᶿ=ᶿ holds to within 10% error is
**A. ** 10º

**B. ** 18º

**C. ** 50º

**D. ** 90º

**Answer : ****Option B**

**Explaination / Solution: **

Here, as we know

Here, as we know

but for 10% error, we can check option (B) first

so, the error is more than 10%. Hence, for error less than 10%, ᶿ = 18º can have the approximation

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In the circuit shown below, the network N is described by the following Y matrix: the voltage gain (V_{2}/V_{1})is

**A. ** 1/90

**B. ** -1/90

**C. ** -1/99

**D. ** -1/11

**Answer : ****Option D**

**Explaination / Solution: **

From given admittance matrix we get

From given admittance matrix we get

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The fourier series expansion of the periodic
signal shown below will contain the following nonzero terms

**A. **

**B. **

**C. **

**D. **

**Answer : ****Option D**

**Explaination / Solution: **

⇒ it satisfies the half wave symmetry, so that it contains only odd harmonics.

⇒ it satisfies the half wave symmetry, so that it contains only odd harmonics.

⇒ It satisfies the even symmetry. So b_{n} = 0

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For a periodic signal the
fundamental frequency in radians/s is

**A. ** 100

**B. ** 300

**C. ** 500

**D. ** 1500

**Answer : ****Option A**

**Explaination / Solution: **

No Explaination.

No Explaination.

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