Basic Radio Theory Flashcards
What is the speed of light
300,000,000 m/s (3x10*8)
How far up is the ionosphere from the surface of the earth?
60-400km
What are 3 main types of polarisation?
Linear, circular and Elliptical
What are the different modes of radio wave propagation?
Direct (line of sight)
Diffraction
Reflection
Refraction
What are space waves?
Line of sight signal, directly from transmitter to receiver
What are ground waves?
A form of surface wave, diffracted along the surface of the earth
What are sky waves?
Signal refracted from E and F layers of the ionosphere
What are propagation errors?
Attenuation - weakening or cancelling out of signal
Absorption - taking up or conversion of energy
Interference - effect on each other of 2 signals of same frequency
Fading - variation in degree of interference
What is skip distance?
The distance from the transmitter to the position of the first returning sky wave
What is dead space/skip zone?
The gap between the end of the ground wave and the first returning sky wave
What’s the Doppler effect?
The frequency of a wave increases or decreases if there’s relative motion between the transmitter and the receiver
How are pulses defined?
Pulse length - the duration in time of a pulse, measured in microseconds
Pulse power - the power contained in a single pulse
Continuous power - the average power consumed over time
What is a radio wave (electromagnetic wave) comprised of?
Electrical (E) field
Magnetic (H) field
E and H fields perpendicular to each other
E field aligned with antenna
