Sep 2012Lesson 6.1

Radio

Radio Waves

Reference

From the Ground UpChapter 8.1:RadioPages 209 - 213

Introduction• Radio is the transmission of signals

through the air in the form of electromagnetic waves.

• It’s good to have a background understanding on how radio wave work when flying an aircraft.

Outline• Wavelength• Frequency• Signal Characteristics

Wavelength• Wavelength is the linear measurement of a wave (in

meters)

• A Cycle is the period that a wave vibrates between its crest and trough

Wavelength

Frequency• The Frequency is the cycles per second (in hertz)

• Radio is in the electromagnetic spectrum between 3 kHz and 300 GHz

Low Frequencies High Frequencies

Frequency• Low/Medium Frequencies (LF/MF)

– 30 KHz to 3000 KHz– Air navigation (NDB), short-wave radio

• High Frequencies (HF)– 3,000 to 30,000 KHz– Air-ground communication, AM radio– Waves reflect off ionosphere, therefore have longer range

• Very High Frequencies (VHF)– 30 to 300 MHz– Air navigation (VOR), aviation radio, FM radio

• Ultra High Frequency (UHF)– 300 to 3000 MHz– Government use, air navigation (ILS, DME)

Signal Characteristics• Ground Waves

– Travel along earth’s surface– Dulled by obstacles

• Sky Waves– Travels up into air– Certain frequencies reflect back to the surface from ionosphere

• Skip Zone– Area between ground waves and sky waves– Transmissions very erratic or unheard

• Line of Sight– VHF waves travels straight through air– Aircraft must see station to receive transmissions

Signal Characteristics

Receives sky waves

No signal

Radio station

Surface of Earth

Signal Characteristics

Receivesground waves

In skip zone,Receives nosignal Receives

reflectedsky waves

Ionosphere

Next Lesson

6.2 – RadioCommunication

From the Ground UpChapter 8.4:Radio Communication ProceduresPages 219 - 229