Radar 2

Question 1

Describe the relationship between Antenna Size and Beamwidth.

Answer 1

Beamwidth (BW) is determined by the antenna dimensions and the frequency (or wavelength) of the transmitted signal.
* BW ≈ wavelength (λ) / Antenna size

Typically: The Larger the Antenna Dimension the Narrower the Beamwidth
• The larger the horizontal antenna dimension, the narrower the azimuth
beamwidth.
• The larger the vertical antenna dimension, the narrower the elevation
beamwidth.

Question 2

Define Nominal Beamwidth.

Answer 2

Nominal Beamwidth is the beam angle that contains at least half the peak power (½ power points, or – 3dB points) of the main-lobe.

Question 3

Define Angular Resolution.

Answer 3

Angular Resolution is defined as the smallest angle in the horizontal plane in which two targets can be resolved.

Question 4

Define Radar Cross Section (RCS).

Answer 4

The effective area of a target that intercepts the transmitted radar power and then scatters that power back to the radar receiver.

Question 5

Define Effective Beamwidth.

Answer 5

Effective Beamwidth is the beam angle that contains sufficient returned power from an object to produce a radar paint.

Question 6

Illustrate and describe the concept of side-lobes.

Answer 6

A side-lobe is any area into which power is radiated other than the main-lobe.
* Side-lobes are a spillover of power that form subsidiary beams either side of the main beam.
* They can be reduced in the design stages, but never completely eliminated.

Question 7

Describe Antenna Gain and Pulses per Paint

Answer 7

Antenna Gain - The ability of an antenna to focus energy (Directivity)

Puleses per Paint - Number of pulses of radar energy incident upon a target.