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- Question
A 75 ohm line is first short terminated and minima locations are noted. Then the short is replaced by resistive load and minima location are again noted. If minima location are not altered and VSWR is 3, the value of resistive load is
Options- A. 25 ?
- B. 50 ?
- C. 225 ?
- D. 250 ?
- Correct Answer
- 225 ?
Explanationrv
and VSWR 
.
Microwave Communication problems
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- 1. A circular waveguide carries TE11 mode whole radial electric field is given by
Er = E0j1(r) sin ? V/m
where r is radial distance in cm from the axis
The cut off wavelength is
Options- A. 10 cm
- B. 3 p cm
- C. 2 p cm
- D. 8 cm Discuss
Correct Answer: 10 cm
- 2. For a rectangular waveguide having width a and height b, the cutoff wavelength for TM11 mode is equal to
Options- A.
- B.
- C.
- D.
Discuss
Correct Answer:
- 3. A circular polarizer converts a linearly polarized wave into a circularly polarised wave.
Options- A. True
- B. False Discuss
Correct Answer: True
- 4. In a circular waveguide with radius r, the dominant mode is
Options- A. TM01
- B. TE01
- C. TM11
- D. TE11 Discuss
Correct Answer: TE01
Explanation:
Some applications require dual polarization capability. Circular waveguide has this capability.These analysis uses cylindrical coordinates.
In circular waveguide TE11 mode has the lowest cut off frequency and is the dominant mode.
If D is diameter of waveguide
?c = 1.706 D for TE11 mode
?c = 1.029 D for TE21 mode
?c = 0.82 D for TE01 mode
?c = 1.306 D for TM01 mode.
- 5. Consider the following time parameters
- Domain growth time constant.
- Transit time.
- Dielectric relaxation time in positive mobility regime.
Options- A. 1, 2, and 3
- B. 1 and 2 only
- C. 1 and 3 only
- D. 2 and 3 only Discuss
Correct Answer: 1, 2, and 3
- 6. As frequency increases, the transmission efficiency
Options- A. decreases
- B. increases
- C. is not affected
- D. either (a) or (c) Discuss
Correct Answer: increases
- 7. A parametric amplifier uses
Options- A. non linear resistance
- B. non linear reactance
- C. either (a) or (b)
- D. neither (a) nor (b) Discuss
Correct Answer: non linear reactance
Explanation:
In a parametric amplifier the non-linear element is varactor diode or inductor.- 8. Effect of loading of line is
Options- A. increase in Z0, a and ?
- B. increase in Z0 and ? but decrease in a
- C. decrease in Z0, a and ?
- D. decrease in Z0 and ? but increase in a Discuss
Correct Answer: increase in Z0 and ? but decrease in a
- 9. If the repeller voltage in a klystron oscillator is increased the transit time of electron
Options- A. will be increased
- B. will be decreased
- C. will remain the same
- D. either (a) or (b) Discuss
Correct Answer: will remain the same
- 10. In a magnetron the magnetic flux density is of the order of
Options- A. 1 mWb/s
- B. 1 Wb/m2
- C. 106 m/s
- D. 1012 m/s Discuss
Correct Answer: 1 mWb/s
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- 1. A circular waveguide carries TE11 mode whole radial electric field is given by
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