Radar- Factors Affecting Coverage

Question 1

Radar systems need to be able to….

Answer 1

Identify the range and azimuth of each aircraft within its range coverage.

Question 2

The accuracy in which a radar system is able to identify range and azimuth of each target within its range is known as…

Answer 2

Resolution of radar

Question 3

List the 7 factors that determine Radar coverage

Answer 3

1) Aerial Size/Shape/height above ground
2) size of target (PSR)
3) Atmospheric conditions
4) Transmitter Power
5) Receiver Efficiency
6) Pulse Recurrence Frequency (PRF; PSR only)
7) Pulse Length (PSR only)

Question 4

What is the usual requirement for aerials in ATC?

Answer 4

A narrow azimuth beam combined with a wide beam in eleveation

Question 5

What is the usual beam width?

Answer 5

2-3 degrees

Note at 60nm would give coverage of 2-3m

Question 6

If a narrow beam is required then the aerial dimensions must be?

Answer 6

Large

Question 7

The height of the aerial above the ground must be considered with reference to?

Answer 7

The wavelength

Question 8

For a given aerial height the shorter the wave length the…

Answer 8

More gaps in high coverage but better will be the low coverage

Question 9

For a given aerial height, the longer the wave length the….

Answer 9

Fewer gaps in high coverage but low coverage will be poor.

Question 10

Radars use the “cosecant squared” radiation pattern to avoid wasting energy.
True or False?

Answer 10

True

Question 11

What information will a vertical coverage diagram display?

Answer 11

The theoretical coverage of display?

Question 12

What 3 things does the vertical coverage diagram take into account?

Answer 12

1) General Design Factors
2) Environment Conditions
3) Atmospheric Conditions

Question 13

What does the Unit Coverage Diagram (UCD) show?

Answer 13

Shows actual coverage of radar system after it has been installed at a specific location

Question 14

What does a unit coverage diagram (UCD) take into account?

Answer 14

Local terrain

Question 15

The shorter the wavelength the greater the atmospheric effects. True or False?

Answer 15

True.

Question 16

Short range radar uses which wave length?

Answer 16

3-10cm

Question 17

Long range area radar uses what wave length?

Answer 17

23-50cm

Question 18

What does Anoprop (Super-refraction) do?

Answer 18

Produces radar echoes below normal coverage and from ranges in excess of this allowed in the design of the radar.

Question 19

Transmitting power for PSR must be…

Answer 19

Sufficient allowing for attenuation for the radar to detect an echo from an aircraft at maximum range

Question 20

Transmitting power for SSR must be….

Answer 20

Sufficient allowing for attenuation for interrogation signal to reach an aircraft at maximum range.

Question 21

What does PRF stand for?

Answer 21

Pulse Recurrence Frequency

Question 22

The higher the PRF (together with beam width and scanning rate) the more “hits” on a target and the stronger and more recognisable will be the return.

True or False?

Answer 22

True.

Question 23

PRF must be

Answer 23

Low enough to accommodate the required maximum range.

Question 24

Pulse length will affect minimum range of a primary radar system. And cannot receive return if Transmitting.
True or False?

Answer 24

True.

Question 25

A narrow beam equals a large aenal dimensions

Answer 25

True