Discussion
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- Question
In an infinite line the input impedance at every point is equal to characteristic impedance.
Options- A. True
- B. False
- Correct Answer
- True
- 1. The inductance of a twin feeder used to connect antenna to TV receiver is about
Options- A. 0.2 ? H/m
- B. 0.6 ? H/m
- C. 1.6 ? H/m
- D. 10 ? H/m Discuss
- 2. 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
- 3. 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
- 4. 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
- 5. 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
- 6. The domain mode in rectangular waveguide is
Options- A. TE01
- B. TE02
- C. TE10
- D. TM11 Discuss
- 7. The number of PM radio channels which can be accommodated in a spectrum of 300 MHz is about
Options- A. 10
- B. 100
- C. 500
- D. 1500 Discuss
- 8. In a klystron amplifier the force on all electrons
Options- A. causes acceleration of all electrons
- B. causes retardation of all electrons
- C. causes acceleration of some electrons and retardation of others
- D. none of the above Discuss
- 9. In a line with finite attenuation
Options- A. power transmission is least efficient when there are no standing waves on the line
- B. power transmission is most efficient when there are no standing waves on line
- C. Load power depends on phase constant
- D. standing waves will always exist on the line Discuss
- 10. If load impedance ZL >> Z0, then
Options- A. Z0 = ZL (VSWR)
- B. ZL = Z0 (VSWR)
- C. ZL = Z0 (VSWR - 1)
- D. ZL = Z0 VSWR Discuss
Microwave Communication problems
Search Results
Correct Answer: 1.6 ? H/m
Correct Answer: long range navigation
Correct Answer: p+ and n+ layers separated by i layer
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: 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: TE10
Correct Answer: 1500
Correct Answer: causes acceleration of some electrons and retardation of others
Explanation:
An electron beam is produced by oxide coated indirectly heated cathode and is focussed and accelerated by focussing electrode.
This beam is transmitted through a glass tube. The input cavity where the beam enters the glass tube is called buncher.
As electrons move ahead they see an accelerating field for half cycle and retarding field for the other half cycle.
Therefore, some electrons are accelerated and some are retarded. This process is called velocity modulation.
The velocity modulation causes bunching of electrons. This bunching effect converts velocity modulation into density modulation of beam.
The input is fed at buncher cavity and output is taken at catcher cavity.
In a two cavity klystron only buncher and catcher cavity are used. In multi cavity klystron one or more intermediate cavities are also used.
The features of a multicavity klystron are :
1. Frequency range - 0.25 GHz to 100 GHz
2. Power output - 10 kW to several hundred kW
3. Power gain - 60 dB (nominal value)
4. Efficiency - about 40%.
A multicavity klystron is used in UHF TV transmitters, Radar transmitter and satellite communication.
Correct Answer: power transmission is most efficient when there are no standing waves on line
Explanation:
Correct Answer: ZL = Z0 (VSWR)
Explanation:
and VSWR 
. Therefore ZL = Z0(VSWR).
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