Propagation Flashcards
Reflection
reflectivity depend on wavelenght reflection increase as wavelenght equal target size
refraction
change in medium(density) higher f less refraction costal athmosferic ionoshperic
Diffraction
radio wave hit “sharped edge) and change his propagation
Attenuation
loss of signal strenght
surface incr F incr Atten
Atmospheric incr F incr Atten
Ionosph incr F decrease Atten
range
to double the range you need to increase the power of four
static
thunderstorm
worst at lower frequency
nil from VHF and bove
precipitation static
rain hitting the A/C can create electic discharge worst at LF and MF
Noise
man made
unschield electrical equipment
Worst @VHF and above
interference
similar frequency
Fading
can create from interference and is the change in signal strenght due to phase difference
Signal/Noise ratio
DB comparison btn signal strenght and unwanted signal
Direct wave
straight line
VHF and up
no reffraction in the ionoshpere
surface wave short
reflected wave
coming from directed wave and reflect by terrain
Sky wave
VHF and above
the sum of direct and reflected wave
duct propagation
also call super refraction is warm air above normal air that reflect the space wave
