Discussion
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- Question
In the given figure shows the equivalent circuit of a magic tee. If all ports are matched
Options- A. nE = nH = 2
- B. nE = nH = 0.707
- C. nE = 2, nH = 0.707
- D. nH = 0.707, nH = 2
- Correct Answer
- nE = nH = 2
- 1. A reflex klystron oscillator is a
Options- A. low power device
- B. high power device
- C. high efficiency device
- D. both (a) and (b) Discuss
- 2. Assertion (A): Gunn diode is a transferred electron device.
Reason (R): A Gunn oscillator uses the phenomenon of transferred electron effect.
Options- A. Both A and R are correct and R is correct explanation of A
- B. Both A and R are correct but R is not correct explanation of A
- C. A is correct but R is wrong
- D. A is wrong but R is correct Discuss
- 3. Read the following statements about TWT
- It uses thermionic emission.
- It uses an attenuater.
- It is inherently a resonant device.
- It has broad bandwidth.
Options- A. 1, 2, 3 and 4
- B. 1, 2 and 3
- C. 1, 3 and 4
- D. 1, 2 and 4 Discuss
- 4. For matching over a range of frequencies in a transmission line it is best to use
Options- A. a balun
- B. a broad band directional coupler
- C. double stub
- D. a single stub of adjustable position Discuss
- 5. Assertion (A): For high frequency lines inductive reactance is very high as compared to ac resistance.
Reason (R): Due to skin effect ac resistance of line is higher than dc resistance.
Options- A. Both A and R are correct and R is correct explanation of A
- B. Both A and R are correct but R is not correct explanation of A
- C. A is correct but R is wrong
- D. A is wrong but R is correct Discuss
- 6. If ZTE is wave impedance for TE waves, Ed is maximum dielectric strength of insulating material, a and b are the width and height of a rectangular wave guide, the maximum power handling capability Pmax for TE10 mode is
Options- A.
- B.
- C.
- D.
Discuss
- 7. Assertion (A): Impatt diode can be used in both amplifiers and oscillators.
Reason (R): Impatt diode has a low resistance.
Options- A. Both A and R are correct and R is correct explanation of A
- B. Both A and R are correct but R is not correct explanation of A
- C. A is correct but R is wrong
- D. A is wrong but R is correct Discuss
- 8. Assertion (A): Microstrip is very commonly used in microwave integrated circuits.
Reason (R): Microstrip has an easy access to the top-surface so that active and passive discrete components can be easily mounted.
Options- A. Both A and R are correct and R is correct explanation of A
- B. Both A and R are correct but R is not correct explanation of A
- C. A is correct but R is wrong
- D. A is wrong but R is correct Discuss
- 9. PIN diode has
Options- A. p+ and n layers separated by i layer
- B. p+ and n+ layers separated by i layer
- C. p- and n- layers separated by i layer
- D. none of the above Discuss
- 10. The word 'LORAN' means
Options- A. long range navigation
- B. long range TV transmission
- C. long range cable transmission
- D. either (b) or (c) Discuss
Microwave Communication problems
Search Results
Correct Answer: low power device
Explanation:
Its parts are electron gun, resonator, repeller and output coupling.
It operates on the principle of positive feed back.
The repeller electrode is at negative potential and sends the partially bunched electron beam back to resonator cavity.
This positive feedback supports oscillations. Its feature are:
1. Frequency range - 2 to 100 GHz
2. Power output - 10 MW to about 2 W
3. Efficiency - 10 - 20 %
Its applications include radar receivers, local oscillator in microwave devices, oscillator for microwave measurements in laboratories etc.
Correct Answer: Both A and R are correct but R is not correct explanation of A
Explanation:
This effects is called transferred electron effect. The impedance of a Gunn diode is tens of ohms.
A Gunn diode oscillator has a resonant cavity, an arrangement to couple Gunn diode to cavity, biasing arrangement for Gunn diode and arrangement to couple RF power to load.
Applications of Gunn diode oscillator include continuous wave radar, pulsed radar and microwave receivers.
Correct Answer: 1, 2 and 4
Explanation:
A TWT is a broadband device. Its main components are electron gun (to produce the electron beam) and a structure supporting the slow electromagnetic wave.
The velocity of wave propagation along the helix structure is less than velocity of light.
The beam and wave travel along the structure at the same speed.
Thus interaction occurs between beam and wave and the beam delivers energy to the RF wave.
Therefore the signal gets strengthened and amplified output is delivered at the other end of tube.
The main features of TWT are :
1. Frequency range - 0.5 GHz to 90 GHz
2. Power output - 5 mW at low frequencies(less than 20 GHz) 250 kW (continuous wave) at 3 GHz 10 MW (pulsed) at 3 GHz
3. Efficiency - about 5 to 20%
4. Noise - about 5 dB for low power TWT 25 dB for high power TWT
TWT is used as RF amplifier in broadband microwave receivers, repeater amplifier in broad band communication systems, communication satellites etc.
Correct Answer: double stub
Explanation:
Correct Answer: Both A and R are correct but R is not correct explanation of A
Explanation:
Correct Answer:
Correct Answer: Both A and R are correct but R is not correct explanation of A
Explanation:
It exhibits negative resistance and operates on the principle of avalanche breakdown.
Impatt diode circuits are classified as broadly tunable circuit, low Q circuit and high Q circuit.
The impedance of Impatt diode is a few ohms. The word Impatt stands for Impact Avalanche Transit Time diode.
The features of Impatt diode oscillator are : frequency 1 to 300 GHz, Power output (0.5 W to 5 W for single diode circuit and upto 40 W for combination of several diodes), efficiency about 20%.
Its applications include police radar systems, low power microwave transmitter etc.
Correct Answer: Both A and R are correct and R is correct explanation of A
Explanation:
Its special feature is easy access to top surface so that minor adjustments can be made after circuit fabrication.
The high dielectric constant of the substrate reduces guide wavelength and circuit dimensions.
A microstrip line is the most commomly used transmission structure for microwave integrated circuits.
Correct Answer: p+ and n+ layers separated by i layer
Correct Answer: long range navigation
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