Design Factors

Question 1

What factors affect Radar Coverage? (7)

Answer 1

• Aerial size, shape and height above the ground.
• Size of the target - Primary Radar only.
• Atmospheric conditions.
• Transmitter power.
• Receiver efficiency.
• Pulse Recurrence Frequency (PRF) - Primary Radar only.
• Pulse Length - Primary Radar only.

Question 2

What are operational radar procedures determined from?

Answer 2

UCD
Unit Coverage Diagram

Question 3

What is a UCD?

Answer 3

A Unit Coverage Diagram (UCD) shows the
actual coverage of the radar system after it has
been installed at a specific location.
It takes into account the local terrain, hills,
valleys etc. and thus it is unique to each
particular installation

Question 4

Design factors for Aerials?

Answer 4

The usual beam width is 2-3 degrees which at
60nm would give a coverage of 2-3nm.

Question 5

Aerial height relationship

Answer 5

For a given aerial height,
the shorter the wavelength the more gaps in high coverage but the better will be the low coverage. (Approach)
Conversely, for a given aerial height, the longer the wavelength the fewer gaps in high coverage but the low coverage will be poorer. (ACC)

Question 6

What is PRF?

Answer 6

Pulse reccurence Frequency

The higher the PRF (together with beam width
and scanning rate) the more ‘hits’ on a target
and hence the stronger and more recognisable
will be the return.
The PRF is, however, a compromise as it must be
low enough to accommodate the required
maximum range.