Radio Theory

Question 1

What are the 5 bands of frequencies that we use in aviation?

Answer 1

• Low (LF)
• Medium (MF)
• High (HF)
• Very High (VHF)
• Ultra High (UHF)

Question 2

Where are you most likely to see High Frequency (HF) radio?

Answer 2

Far north or Trans-Atlantic

Question 3

What is High Frequency (HF)?

Answer 3

• 3000 - 30000 KHZ
• Use for long range air and ground comms
• Its range is dependant on conditions in the ionosphere (Sun up, Frequency up. Sun down, Frequency down). During the day you will use 5000Khz and above. At night, you’ll use around 3000Khz.

Question 4

In Northern Canada where VHF cannot be established, what specific frequency will you use?

Answer 4

5680Khz

Question 5

What is VHF?

Answer 5

• 30 - 300 Mhz
• Very High Frequency
• Used extensively in aviation navigation aids and comms

Question 6

What VHF channel ranges do we use for VOR and voice comms?

Answer 6

• VOR: 112.00 - 117.95 Mhz
• Voice: 118.00 - 137.00 Mhz

Question 7

LM, MF, HF are all in _hz

Answer 7

Khz

Question 8

VHF and UHF are in _hz

Answer 8

Mhz (Mega)

Question 9

What is the ILS (Instrument Landing System) radio range?

Answer 9

108.10 - 111.95

Question 10

What are the radio channel ranges for ILS, VOR, and Voice comms?

Answer 10

ILS: 108.10 - 111.95
VOR: 112.00 - 117.95
Voice: 118.00 - 137.00

Question 11

What phenomenon is the reason VHF and UHF frequencies have very few ground waves?

Answer 11

Attenuation (objects in the way)

Question 12

What frequency range is UHF in?

Answer 12

300 - 3000 Mhz
Mostly used by the military and gov, but DMEs are also in this range.

Question 13

What are ground waves?

Answer 13

Question 14

What are sky waves?

Answer 14

Question 15

More on sky waves

Answer 15

Question 16

Line of Sight frequencies diagram

Answer 16

Question 17

What is the formula to figure out if you can get a VOR/VHF signal?

Answer 17

1.25 x Sq Root of your AGL

The answer is the farthest distance away that you can be and still get the signal. So as long as whatever distance they gave you in the question is less that what the formula answer is, then you can receive the signal.

Question 18

What is HF Single Sideband frequency?

Answer 18

It removes the carrier frequency (which decreases necessary power usage) and one of the side frequencies, and uses only a single side band frequency to broadcast (saves on band space)

Question 19

In what range (LF, MF, HF, VHF, UHF) does a NDB operate?

Answer 19

LF and MF

Question 20

LF and MF frequencies operate in the range of…

Answer 20

30 - 3000 Khz

Question 21

HF range is used for:

Answer 21

long range air/ground voice communications

Question 22

What two frequency ranges does an NDB use?

Answer 22

190 - 415 - 510 - 535