Radio Principles

Question 1

Electromagnetic waves

Answer 1

Radiation Pattern
–Varies with antenna shape
–Purpose specific
- Energy movement
Transmitted
– Light, Electricity

Question 2

Frequency

Answer 2

Number of cycles completed in one unit of time
Measured per second
–Kilohertz is 1000s cycles per second
–Megahertz is millions of cycles per second

Question 3

Wavelength

Answer 3

Distance between peaks of repeating wave
Inversely proportional to frequency

Question 4

Current

Answer 4

Flow of electrons through a conductor
Direct Current – DC
–Aircraft Systems
Alternating Current – AC
–Outlets, Larger aircraft systems

Question 5

Characteristics of waves

Answer 5

All matter has a varying degree of resistance to radio waves
–Earth is greatest resistor
Strength of signal decreases over distance
Different frequencies and equipment are used depending on requirements

Question 6

Ground waves

Answer 6

100 Hz – 1000 kHz (1MHz)
Travels across the Earth’s surface
–Generally the lower the frequency the farther it will travel
Navigation Purposes
–Consistent path through atmosphere
–NDBs

Question 7

Sky waves

Answer 7

1-30 MHz
Characteristics
–Good for long distances (Shortwave Radio)
–Refracted from ionosphere
Not used in modern navigation
–Does not follow consistent path
Why? Ionosphere altered by Sun intensity
High Frequency Transmissions (HF)

Question 8

Space waves

Answer 8

15 MHz – many GHz
Able to pass through ionosphere
–However they are used prior to reaching the ionosphere, except GPS
Unit itself corrects for propagation error
Errors of Space Waves
–Reflection
–Blocked
–Propeller Modulation
–Line of Sight
Most navigation systems use space waves

Question 9

Characteristics of bands

Answer 9

Lower Frequencies
–long distance
–long antennas
–ground waves
–sky waves
–subject to interference
Higher Frequencies
–line of sight
–short antennas
–little interference

Question 10

Disturbances to radio waves

Answer 10

Precipitation Static Causes:
–Complete loss of VHF equipment
–Erroneous magnetic compass readings
–High pitched radio squeal
–Loss of all avionics

Question 11

St. Elmo’s fire

Answer 11

Named after the patron saint of the sailors
–St. Erasmus of Formiae (St. Elmo)
–The phenomenom sometimes appeared at sea
Bright blue or violet glow

Question 12

Basic navigation equipment

Answer 12

Signal generating device
Transmitter
Antennas
Receiver
Instruments for visual presentations

Question 13

Navigation aids

Answer 13

VOR
NDB
ILS
DME
Radar
GPS

Question 14

Types of radio navigation

Answer 14

VOR
Localizer
NDB
GPS
RADAR

Question 15

Required for IFR flight

Answer 15

No Minimum Navigation Radio Equipment is Required
You only need what you intend to use on a particular flight