L1 VHF Propagation Principles

Flashcards about VHF Propagation Principles

What is the frequency range for Very Low Frequency (VLF)?

3 kHz - 30 kHz

What is the usage of Very Low Frequency (VLF)?

Omega long range navigation aid

What is the frequency range for Low Frequency (LF)?

30 kHz - 300 kHz

What is the usage of Low Frequency (LF)?

Aviation and maritime navigation aids

What is the frequency range for Medium Frequency (MF)?

300 kHz - 3 MHz

What is the usage of Medium Frequency (MF)?

Aviation and maritime navigation aids, AM commercial radio broadcast

What is the frequency range for High Frequency (HF)?

3 MHz - 30 MHz

What is the usage of High Frequency (HF)?

Long range maritime and aviation communication, 'short wave' commercial radio

What is the frequency range for Very High Frequency (VHF)?

30 MHz - 300 MHz

What is the usage of Very High Frequency (VHF)?

Maritime and aviation communications, FM commercial radio, TV broadcast, emergency services radio

What is the frequency range for Ultra High Frequency (UHF)?

300 MHz - 3 GHz

What is the usage of Ultra High Frequency (UHF)?

Military aircraft communications, aircraft radar, TV broadcast, mobile phone

What is the frequency range for Super High Frequency (SHF)?

3 GHz - 300 GHz

What is the usage of Super High Frequency (SHF)?

Radio astronomy, radar and satellite

What frequency range does the VHF band cover?

30 MHz to 300 MHz

What types of services use the VHF band?

FM commercial radio, marine radio, emergency communications and some radio navigation aids

In what frequency range does civilian aircraft voice communications take place in the VHF band?

118 MHz and 137 MHz

How many discreet channels were provided in the 118.000 MHz to 137.000 MHz band with 25 kHz spacing?

760

What was the reduced channel bandwidth implemented to increase the number of channels?

8.33 kHz

How many channels are available with the 8.33 kHz spacing in the VHF band?

2280

On what frequency does the channel 118.005 MHz actually transmit?

118.0000 MHz

On what frequency does the channel 118.010 MHz actually transmit?

118.0083 MHz

On what frequency does the channel 118.015 MHz actually transmit?

118.0167 MHz

On what frequency does the channel 118.030 MHz actually transmit?

118.0250 MHz

On what frequency does the channel 118.035 MHz actually transmit?

118.0333 MHz

Post-January 2019, what are frequencies officially called?

'channels'

How do VHF radio electromagnetic waves travel?

Straight line

What is the feature of VHF transmissions often described as?

Line-of-sight

On the ground, what is the approximate distance to the horizon?

2.5 nautical miles

Approximately how far can VHF transmissions reach from 1000 ft above the surface?

39 nautical miles

Approximately how far can VHF transmissions reach from 10000 ft above the surface?

122 nautical miles

What happens when you increase the height of a VHF radio installation?

Increases its range

What is the theoretical VHF range at 5000 ft?

86 NM

What is the theoretical VHF range at 13,000 ft?

140 NM

What atmospheric condition can lead to duct propagation?

Temperature inversion

During duct propagation, how much can the range of VHF transmissions at low levels increase?

Increase by two or three times their normal distance

What unusual activity in the ionosphere can massively increase the range of VHF transmissions?

Sporadic E

Why do planners try to ensure airfields using the same frequency are far apart?

Avoid interference

Approximately how far apart are Gloucestershire airport tower and Dundee airport tower?

275 nautical miles

What type of radio is used for long-distance aircraft voice communications?

High Frequency (HF) radio

What factors affect High Frequency radio?

Time of day, seasons, and sun activity

What is the frequency range for Very Low Frequency (VLF) transmissions?

3 kHz to 30 kHz

What is the frequency range for Low Frequency (LF) transmissions?

30 kHz to 300 kHz

What is the frequency range for Medium Frequency (MF) transmissions?

300 kHz to 3 MHz

What is the frequency range for High Frequency (HF) transmissions?

3 MHz to 30 MHz

What is the frequency range for Very High Frequency (VHF) transmissions?

30 MHz to 300 MHz

What is the frequency range for Ultra High Frequency (UHF) transmissions?

300 MHz to 3 GHz

What is the frequency range for Super High Frequency (SHF) transmissions?

3 GHz to 300 GHz

What is Low Frequency (LF) primarily used for?

Aviation and maritime navigation

What is Medium Frequency (MF) primarily used for?

Aviation and maritime navigation, AM radio

What is High Frequency (HF) primarily used for?

Long-range communication

What is Very High Frequency (VHF) primarily used for?

Maritime, aviation communications, TV, radio and emergency services

What is Ultra High Frequency (UHF) primarily used for?

Military communications, radar, TV, mobile phones

What is Super High Frequency (SHF) primarily used for?

Radio astronomy, radar, satellites

How many channels were possible with 25 kHz spacing?

760

What is the current channel spacing?

8.33 kHz

How many channels are possible with 8.33 kHz spacing?

2280

How do VHF waves propagate?

Straight line

VHF propagation is usually described as what?

Line of Sight

What is the theoretical VHF range on the ground?

2.5 NM

What is the theoretical VHF range at 1000 ft?

38 NM

What is the theoretical VHF range at 3000 ft?

67 NM

What is the theoretical VHF range at 5000 ft?

86 NM

What is the theoretical VHF range at 10,000 ft?

123 NM

What is the theoretical VHF range at 13,000 ft?

140 NM

What is a temperature inversion?

Temperature increases with height

What phenomenon can temperature inversions cause?

Duct Propagation

How much can duct propagation increase VHF range?

Two to three times

What is it called when there is unusual activity in the ionosphere?

Sporadic E

What frequency range is used for long distance communications?

HF

How far apart are Gloucestershire and Dundee airports?

275 NM

What frequency is mainly used for ground to air communication?

VHF

What primary navigation aid does VLF support?

Omega long range navigation aid

Besides aviation, what other mode of transport uses LF?

Maritime

What type of radio broadcast uses MF?

AM Radio

What is common name for HF commercial radio?

Short wave radio

How fast do VHF transmissions travel?

Speed of light

What happens in duct propagation?

Radio waves refract/bend

What causes sporadic-E?

Solar flares

What long range navigation aid corresponds to VLF?

Omega

What application uses LF?

Navigation

What application uses MF?

Broadcasting

What application uses HF?

Shortwave

What application uses VHF?

Air Traffic Control

What application uses UHF?

Mobile Phones

What application uses SHF?

Satellite Communication

How did channel separation decrease in the VHF band to create more channels?

25 kHz to 8.33 kHz

What principle explains the line-of-sight requirement for VHF transmissions?

Electromagnetic waves travel in a straight line

What type of system uses VLF frequencies?

Omega Navigation

What modes of transport use LF frequencies for navigation?

Aviation and Maritime Systems

What main type of Radio is on MF?

AM broadcast

Who uses VHF radio?

Both military and civilian

What consumer device uses UHF signals?

Mobile phones

What enables SHF to reach very long distances?

Satellite

What is the most common aviation communication band?

VHF

What phenomenon greatly extend s VHF range?

Ducting

Sporadic E occurs at what sphere?

Ionosphere

What was legacy VHF frequency width?

25 kHz

What is the current VHF frequency widths?

8.33 kHz

What impacts VHF distances

Line of Sight