2. Tracking Radar
Measures the coordinate of a target for determining the
target path as well as to predict its future coordinates
Based on the measured coordinated error signal will be
generated
Antenna should be moved based on error signal to
maintain the target within the beam.
Tracking of range, angle, Doppler frequency shift and
radial velocity
Uses pencil beam

3. Angle tracking
 Two beams are squinted
 Crossover of two beam:
boresight
 Boresight always maintained in
the direction of the target
 Relative amplitude of two beam
determines how far the target is
from boresight
 Also direction in which beam
needs to be repositioned
 2 beams in both the coordinate

4. Methods of generating error signal
Conical scan or sequential lobing tracker
Time shares a single beam
Antenna beam is switched between two positions
Simultaneous lobing or monopulse
More than one simultaneous beam is used for tracking
Usually 4 simultaneous beams to perform 2
dimensional tracking

5. MonopulseTracking Radar
Radar in which information concerning the angular
location of the target is obtained by comparing the
signal received in two or more simultaneous beams.
Two offset antenna beams are combined to obtain
both sum and difference signal
This signals are multiplied in a phase sensitive
detector to obtain both magnitude and direction

6. Amplitude comparison monopulse

7. Amplitude comparison monopulse
Two
adjacent antenna
feeds are connected to the
2 input arms of a hybrid
junction
Sum and difference signal
Difference
channel
produce error voltage
appro proportional to the
angular deviation of the
target from the boresight

8. Amplitude comparison monopulse
By comparing the phase of sum and difference signal
direction of angle error is found
Depending on these information's the servo meter will
drive the antenna back to the target
Phase sensitive detector is used to compare the phase
of two signals

9. Monopulse in two angle coordinate

10. Monopulse in two angle coordinate

11. Monopulse in two angle coordinate
All four feeds are used to generate sum pattern
i.e A+B+C+D
Azimuth difference channel: (A+B) – (C+D)
Elevation difference channel: (B+D) – (A+C)
Two angle errors
Elevation angle error : o/p of phase comparison b/w
sum channel and Elevation difference channel
Azimuth angle error : o/p of phase comparison b/w
sum channel and Azimuth difference channel

12. Phase comparison monopulse
Instead of comparing the amplitude of the echoes
from two squinted beams , the angle of arrival from a
target is determined by comparing the phase
difference between two signals
Uses two separate beams from two separate antenna
looking in same direction

13. Phase comparison monopulse
An echo on boresight will arrive
at the two antennas at the same
time and therefore the phase
difference will be zero
An echo from a target at an angle
q to boresight will arrive at one
antenna later than the other due
to the extra distance it travels.

14. Phase comparison monopulse
Extra distance travelled
by one echo w.r.t other
is given by
Or expressed as phase
difference
Phase detector is used
to find the angle error

15. Phase comparison monopulse

16. Comparison
Amplitude-comparison
Phase comparioson
Has high SNR
Grating effect : high
Two feeds at the focus of
single antenna
Squinted beams used
sidelobes are produced in the
sum pattern resulting in
angle measurement
ambiguities
 two separate antenna are
used
Beams are not squinted but
look in same direction