Microwave/Satellite Communication

Microwave resonators are used in

• microwave oscillators

• microwave narrow band amplifier

• 
  microwave frequency metres

• 
  all of the above

In microwave system the function of mode filter is

• 
  to suppress modes with lower cut off frequencies

• 
  b. to suppress modes with higher cut off frequencies

• 
  to change mode of wave transmission

  both (b) and (c)

• c. to change mode of wave transmission

Atomic and molecular resonance is observed in many substances

• at microwave frequencies

• at low frequencies

• at frequencies used in AM broadcast

• 
  at both (light blue) and (yellow)

Microwave links are typically 50 km apart

• because of atmospheric attenuation

• 
  because of output tube power limitation

• because of earth's curvature

• to ensure that applied dc voltage is not excessive

Satellite communication systems use the frequency band

• 10 to 20 MHz

• 
  50 to 70 MHz

• 3 to 6 GHz

• 100 to 120 GHz

The characteristic impedance of a cable is about

• 300 Ω

• 50 Ω

• 
  5 Ω

• 2 Ω

For a directional coupler the power is in the ratio of

• 40 dB

• 30 dB

• 20 dB

• 
  10 dB

A microwave connector should have high SWR.

• True

• False

In microwave circuits, a mode transducer is used to

• change mode of wave transmission

• change direction of wave transmission

• change polarization of wave transmission

• 
  change mode, direction or polarization wave transmission

Microwaves

• get reflected by ionosphere

• 
  are absorbed by ionosphere

• 
  are neither reflected nor absorbed by ionosphere

• 
  are both reflected and absorbed by ionosphere