11) In an air line, adjacent maxima are found at 12.5 cm and 37.5 cm. The operating frequency is
a) 1.5 GHz
b) 600 MHz
c) 300 MHz
d) 1.2 GHz
12) The phenomenon of microwave signals following the curvature of earth is known as
a) Faraday effect
b) ducting
c) wave tilt
d) troposcatter
13) Following antenna is frequently used for local area transmission at UHF/VHF
a) Ground monopole
b) Turnstile antenna
c) Slot antenna
d) Loop antenna
14) In a line the VSWR of a load is 6dB. The reflection coefficient will be
a) 0.033
b) 0.33
c) 0.66
d) 3.3
15) A waveguide operated below cut-off frequency can be used as
a) A phase shifter
b) An attenuator
c) An isolator
d) None of the above
16) If the phase velocity of a plane wave in a perfect dielectric is 0.4 times its value in free space, then what is the relative permittivity of the dielectric ?
a) 6.25
b) 4.25
c) 2.5
d) 1.25
17) To couple a coaxial line to a parallel wire, it is best to use a
a) Balun
b) Slotted line
c) Directional coupler
d) Quarter wave transformer
18) The dominant mode in a circular waveguide is a
a) TEM mode
b) TM01 mode
c) TE21 mode
d) TE11 mode
19) Equipotential surface about a point charge are in which one of the following forms ?
a) Spheres
b) Planes
c) Cylinders
d) Cubes
20) Which one of the following modes has the highest cut-off wavelength in a rectangular waveguide ?
a) TE10
b) TE01
c) TM01
d) TM11