Radio waves Flashcards
Electromagnetic radiation is made up of
Two waves
-Electricfield traveling vertically
-Magnetic field travel horizontally
Measurements of frequncy :
1 Hz =
1 Khz =
1 Mhz =
1 Hz = 1 complete cycle per second
1 Khz = 1000
1 Mhz = 1 000 000
Advantage of AM over FM would be
Cheaper and simpler
SSB (single side band is)
A refinement of FM
transmittter power and bandwidth is more efficient
Surface waves follow the surface of the earth instead of in a straight line because of
Wave tilting
Frequency mostly used by skywaves returns are
LF
MF
HF
Distance between the first returning sky wave and the end of the surface wave is know as
the dead space
Direct waves produce
VHF
UHF
SHF
Over distance static and atmospheric effects will slowdown or weaken signals is known as
Attenuation
What happens to the inosphere at night and how does it effect hf radio communications
Ionosphere rises at night
and becomes half the day value
minimum angular difference between the vertical and the angle which returns the first sky wave is
The critical angle
Optimum useable frequeny of an HF signal is
0.85 x maximum useable frequency
PSR operates in the
SHF
UHF
Factors that affect PSR
Pulse reccurence frequncy
Mountains
Curvature of earth
Strength of the transmitter
Main factor that affects minimum range of PSR
The pulse width
