Chapter 1, Electromagnetic waves Flashcards
A transmitted radio wave will have a plane
wavefront
In the far field
The lowest layer in the earth’s atmosphere is
The troposphere.
A radio wave at 115 kHz is most likely to
propagate as
A ground wave
The height of the E-layer is approximately
100 km
When a large mass of cold air is overrun by warm air the temperature inversion produced will often result in
Tropospheric ducting
Ionospheric sounding is used to determine
The critical angle and maximum usable frequency for a given path
The critical frequency is directly proportional to
The square root of the electron density
The MF range extends from
300 kHz to 3 MHz
A radio wave has a frequency of 15 MHz.
What is the wavelength of the wave?
20 m
Which one of the following gives the velocity at which a radio wave propagates?
3 × 108 m/s
The main cause of ionisation in the upper
atmosphere is
Solar radiation
The F2-layer is
The same height at the equator as at the
poles
The free-space path loss experienced by a
radio wave
Increases with both frequency and distance
For a given HF radio path, the MUF changes most rapidly at
Dawn and dusk
Radio waves tend to propagate mainly as line-of-sight signals in the
HF band