IFR Navaids - Radio Principles

Precipitation static is minimised by:

• Using short antennae

• Switching off all non-essential equipment

• Coating the aircraft with non-metallic paint

• Fitting discharger wicks to the aircraft

A horizontally polarised signal would be best received by an aerial which is:

• Horizontal

• Vertical

• Either horizontal or vertical

• The plane of the aerial does not matter

A VHF signal is transmitted from an aircraft at FL 230. It will first be received by an aircraft at 5000ft when the aircraft are:

• 209 nm apart

• 222 nm apart

• 260 nm apart

• 278 nm apart

You are flying a navigation exercise at 3000 ft amsl. You wish to contact your destination airfield (100 ft amsl) as soon as possible. What is the theoretical maximum range that you can call the station?

• 71 nm

• 81 nm

• 71 km

• 81 km

A maritime reconnaissance aircraft receives a MAYDAY from a surface vessel at a range of 110 nm. The altitude of the aircraft is:

• 230 ft

• 790 ft

• 2300 ft

• 7750 ft

The rate of attenuation of a radio wave which occurs when the wave travels close to the Earth’s surface:

• Decreases as the frequency of the wave increases, and is greater over the land than the sea

• Increases as the frequency of the wave increases, and is greater over the sea than the land

• Increases as the frequency of the wave increases, and is greater over the land than the sea

• Decreases as the frequency of the wave increases, and is greater over the sea than the land

What is the maximum theoretical range at which a VHF signal will be received by an aircraft flying at FL 200, assuming that the transmitter is sited at 860 ft amsl, and that there is no intervening high ground?

• 180nm

• 144nm

• 170nm

• 213nm

When a waves frequency increases from HF to VHF, atmospheric attenuation ____

• Increase

• Decrease

• No change

Attenuation of a radio wave is the:

• Change of its amplitude by use of side bands

• Change of its frequency by use of side bands

• Reduction of its power by absorption, scattering or dispersion

• Increase of its power by absorption, scattering or dispersion

VHF is a line of sight communication aid, which of the following can affect VHF propagation?

A Transmission power of both the transmitter and the receiver

B The height of the transmitter but not the receiver

C Obstacles at or near the transmitter

D Obstructions in the line of sight

E Attenuation of the direct and ground reflected wave

• All the statements are correct

• A, B, C & D are correct

• A, C, D and E are correct

• A & C are correct