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hbhbjknjndKJKWNDWJN,JN,,NKDNNCM,am,xs,dndx,ms sxmsad, Exercises of Power Electronics

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Typology: Exercises

2017/2018

Uploaded on 11/17/2018

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Fundamentals of Antennas
Week 1 Assignment
1. The measured HPBWs of an antenna in the two orthogonal planes are 30° and 20°. The
approximate gain of the antennain dB is : (2)
a. 17.3dB
b. 18.4dB(Ans)
c. 23.1dB
d. 31.5dB
2. The E-field pattern of an antenna varies as 3+2cosθ, where, angle θ is measured fr om
broadside. The approx. HPBW of the antenna is : (2)
a. 151o
b. 149o (Ans)
c. 31o
d. 25o
3. For an omnidirectional antenna, first null beam width (FNBW) in E-planeis 45o, the
approximate directivity in dB is : (2)
a. 15.2dB
b. 13.0dB
c. 7.6dB(Ans)
d. 6.5dB
4. The axial ratio of an antenna is 1.2. It is acceptable for which polarization : (1)
a. Linear
b. Circular (Ans)
c. Elliptical
d. Depends on the direction of wave propagation
5. If reflection coefficient of an antenna is 0.5at a frequency of 900 MHz, then
5.1 The value of voltage standing wave ratio(VSWR) is: (1)
a. 5
b. 3 (Ans)
c. 2
d. 1
5.2 The percentage power transmittedby antenna is: (1)
a. 75% (Ans)
b. 50%
c. 25%
d. 10%
6. If the antenna input impedanceis (30+j40)Ωat 2.45GHz, the percentage reflected power from
the antenna is : (2)
a. 0
b. 25%(Ans)
c. 75%
d. None of these
7. A GSM1800 cell tower antenna with 16dB gain is transmitting 10W of power at 1845 MHz.
The power density at a distance of 50m in the direction of maximum radiation is : (2)
a. 4.0 mWatt/m2
b. 6.4 mWatt/m2
c. 12.7 mWatt/m2(Ans)
d. 14.2 mWatt/m2
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Fundamentals of Antennas

Week 1 Assignment

  1. The measured HPBWs of an antenna in the two orthogonal planes are 30° and 20°. The approximate gain of the antennain dB is : (2) a. 17.3dB b. 18.4dB(Ans) c. 23.1dB d. 31.5dB
  2. The E-field pattern of an antenna varies as 3+2cosθ, where, angle θ is measured from broadside. The approx. HPBW of the antenna is : (2) a. 151 o b. 149 o^ (Ans) c. 31 o d. 25 o
  3. For an omnidirectional antenna, first null beam width (FNBW) in E-planeis 45 o, the approximate directivity in dB is : (2) a. 15.2dB b. 13.0dB c. 7.6dB(Ans) d. 6.5dB
  4. The axial ratio of an antenna is 1.2. It is acceptable for which polarization : (1) a. Linear b. Circular (Ans) c. Elliptical d. Depends on the direction of wave propagation
  5. If reflection coefficient of an antenna is 0.5at a frequency of 900 MHz, then 5.1 The value of voltage standing wave ratio(VSWR) is: (1) a. 5 b. 3 (Ans) c. 2 d. 1 5.2 The percentage power transmittedby antenna is: (1) a. 75% (Ans) b. 50% c. 25% d. 10%
  6. If the antenna input impedanceis (30+j40)Ωat 2.45GHz, the percentage reflected power from the antenna is : (2) a. 0 b. 25%(Ans) c. 75% d. None of these
  7. A GSM1800 cell tower antenna with 16dB gain is transmitting 10W of power at 1845 MHz. The power density at a distance of 50m in the direction of maximum radiation is : (2) a. 4.0 mWatt/m^2 b. 6.4 mWatt/m^2 c. 12.7 mWatt/m^2 (Ans) d. 14.2 mWatt/m^2
  1. Two identical transmitting and receiving antennasare located at a distance of 2km. Power transmitted is 30dBm at 15GHzand received poweris -70dBm, the approximate gain ofeach antenna is : (2) a. 11dB(Ans) b. 21dB c. 41dB d. 51dB
  2. Transmitting and receiving antennas operating at 1GHz with gains of 20dB and 15dB, respectively, are separated by a distance of 1 km. Assume that the transmitting antenna is circularly polarized and the receiving antenna is linearly polarized. If the transmitted power is 150W, the received power is : (3) a. -5.6dBm b. -7.2dBm c. -8.6dBm(Ans) d. -10.2dBm
  3. The diameter of a parabolic dish antenna for 40dB gain at 11GHz is……:(Assume that efficiency η of the antenna is 65%.) (2) a. 2.0m b. 1.5m c. 1.1m (Ans) d. 0.9m