Practice previous years' questions for Electromagnetics, Antennas, Microwave Engineering, Digital Communication, Signals & Systems, Analog Electronics, VLSI, and Optical Communications.
Marking scheme: +3.00 positive, -0.75 negative (ICRB Standard).
The true statement for wave propagation in rectangular wave guides filled with air is :
As the wave frequency approaches to cut-off frequency of wave guide, the correct statement is :
The EM wave which does not propagate through a rectangular waveguide with $a = 30\text{ mm}$ & $b = 15\text{ mm}$ is :
The minimum input signal that gives output signal to noise ratio of 10 dB in a system that has an input impedance equal to 50 Ω, a noise figure of 4 dB and bandwidth of 100 KHz is :
[$10 \log_{10}(kT_0) = -174\text{ dBm}$]
In this circuit,
$V_{\text{out}}$ is :
The RF amplifier A is having 3 dB NF & 5 dB of gain, amplifier B is having 3.5 dB NF & 15 dB. For overall noise figure of the cascaded system, the correct statement is :
The gain of a parabolic dish antenna of 1 m diameter and 80% efficiency at 9.5 GHz is :
In a uniform linear array, four isotropic radiating elements are spaced $\lambda/4$ apart. The progressive phase shift between the elements required for forming the main beam at $60^\circ$ of the end fire is :
The radiation resistance of a thin line centre fed $\lambda/2$ antenna with sinusoid current distribution is :
To increase gain of a parabolic reflector antenna by 6dBi, the correct statement is :
(Assuming efficiency 70%)
The waveguide Magic Tee can be used as :
The microwave device working on the principal of Faraday rotation is called as :
The phase difference between adjacent anode poles of Magnetron is generally :
Which of the following devices cannot be used as microwave oscillator :
For this RF Circuit, the correct statement is :
For a Phase Locked Loop system, the open loop transfer function is
$$G(s) = \frac{1000}{s\left(\frac{s}{1192} + 1\right)}$$
The phase margin is $50^\circ$ and the crossover frequency is approximately $1000\text{ rad/s}$. A time delay is introduced in the phase detector reducing the phase margin to $40^\circ$. The maximum permissible time delay (in seconds) is :
In this circuit, the relationship between $V_i$ & $V_o$ is :
Output Impedance of a source follower is :
For a negative feedback system shown in Figure,
the equivalent transfer function is :
If $(146)_x + (313)_{x-2} = (246)_8$, then the value of base x is :
The truth table for implementing a boolean variable F is given by
| C | B | A | F |
|---|---|---|---|
| 0 | 0 | 0 | d |
| 0 | 0 | 1 | 1 |
| 0 | 1 | 0 | 1 |
| 0 | 1 | 1 | d |
| 1 | 0 | 0 | 0 |
| 1 | 0 | 1 | 0 |
| 1 | 1 | 0 | 0 |
| 1 | 1 | 1 | 1 |
where d represents don't care states. The minimized expression for F is :
The state transition diagram for a sequence generator is shown in figure
It is designed using D F/Fs and combinational logic blocks $L_0$, $L_1$ & $L_2$ and is initialized at $(Q_2 = 1, Q_1 = 0, Q_0 = 1)$
The minimized expressions for O0, O1 & O2 are :
The number of comparators needed in a 8-bit flash type A to D converter is :
The register in the 8085A that is used to keep track of the memory address of the next op-code to be run in the program is the :
The Complement Accumulator (CMA) instruction of 8085 processor on execution affects :