ESAT CHAPTER 4 4

Line of sight communications is not a factor in which frequency range?

• VHF

• UHF

• HE

• Microwave

Radio waves demonstrated experimentally by:

• Armstrong

• Hertz

• Maxwell

• Marconi

What causes tropospheric ducting of radio waves?

• Lightning between the transmitting and receiving stations

• An aurora to the north

• A temperature inversion

• A very low pressure area

In electromagnetic waves, polarization means

• the physical orientation of magnetic field in space

• the physical orientation of electric field in space

• ionization

• the presence of positive and negative ions

What type of radio propagation where signal travels along the sur of the earth?

• E - layer propagation

• Knife - edge propagation

• Ground wave propagation

• Line of sight propagation

Which polarization can be reasonably well received by a circularly polarized antenna:

• vertical

• horizontal

• circular

• all of the above

Defines as the quotient of the maximum radiation intensity over the average radiation intensity

• Aperture gain

• Directive gain

• Transmission gain

• Power gain

What usually happens to radio waves with frequencies below the maximum usable frequency (MUF) when they are sent into the ionosphere?

• They are changed to a frequency above the MUF

• They are completely absorbed by the ionosphere

• They are bent back to the earth

• They pass through the ionosphere

The quality in sound that corresponds to color in light is

• Amplitude

• Resonance

• Waveform

• Pitch

The ionosphere has its greatest effect on signals in what frequency range?

• 300 kHz to 3 MHz

• 3 to 30 MHz

• 30 to 300 MHz

• Above 300 MHz