Antennas and Wave Propagation Mid - II, November - 2014

1.The magnitude of surface wave tilt depends on
  • conductivity & permittivity of earth
  • reactivity of earth
  • permeability of earth
  • permeability & permittivity of earth
Answer: A
2.MUF is related to the critical frequency and the angle of incidence by the expression
  • MUF =fc r secφ I
  • MUF =fc rcosφ I
  • MUF =fc rsinφ I
  • MUF =fc rtanφ I
Answer: A
3.A Paraboloid reflector of 1.8 m diameter is used at 6GHz.The beam width between the nulls is
  • 7.6º
  • 4.51º
  • 3.89º
  • 9.29º
Answer: C
4.A vertically polarized wave at the surface of earth will have
  • forward tilt
  • backward tilt of 10
  • no tilt
  • backward tilt of 20
Answer: A
5.The refractivity of atmosphere, N is
  • (77.6 / T) P + (4810 e / T)
  • (77.6 / T) + (4810 e / T)
  • P+( 4810 e / T)
  • (77.6 / T) P + (4810 e)
Answer: A
6.One of the following is a delay type lens antenna
  • H plane metal lens
  • E plane metal plate lens
  • EH metal plate
  • Horn
Answer: A
7.The width of the rectangular microstrip antenna using a substrate with dielectric constant of 2.2 and resonate at 10GHz.
  • 2.4cm
  • 0.22 cm
  • 22cm
  • 1.186cm
Answer: B
8.Directivity is
  • D=WT/4ПU (θ, Φ)
  • D=4ПU (θ, Φ)*WT
  • D=4ПU (θ, Φ)/WT
  • D=4ПU (θ, Φ)+WT
Answer: C
9.The Vertical antennas are used for are
  • surface wave propagation
  • ground wave propagation
  • sky wave propagation
  • space wave propagation
Answer: B
10.The disadvantage of E plane metal plate lens is
  • frequency sensitive
  • frequency independent
  • phase sensitive
  • phase independent
Answer: A
11.In the dielectric lens action depends on ----------------------------------- of the wave in lens
Answer: Retardation
12.The region very close to antenna is called ----------------------------------- region.
Answer: Reactive near field
13.The F/D of a parabolic reflector is > ----------------------------------
Answer: 0.25 to 0.5
14.The loss in aperture in Feed antenna blockage is avoided by using -----------------------------------
Answer: Offset feed
15.__________ type of reflector has included angle 90º
Answer: Corner reflector
16.Space wave propagation is a EM wave transmission of frequencies between --------- Hz to --------- Hz
Answer: 30MHz-300MHz
17.The delay type lens antenna is ------------------------------------------
Answer: Dielectric lens
18.Directivity is obtained by the ---------------------------------- expression
Answer: D = 41,253/ θ1. θ 2
19.According to standard condition the distance between two antennas should be ----------------------
Answer: r≥2d²/ λ
20.The antenna which operates at VHF and UHF frequencies is ----------------------------------------
Answer: Yagi-Uda and Folded Dipole