This document discusses tracking radar and monopulse radar. Tracking radar measures target coordinates to determine path and predict future locations. It tracks range, angle, Doppler, and velocity. Monopulse radar obtains angular location using simultaneous beams. It compares signals in sum and difference channels to obtain magnitude and direction of angular errors and keep the antenna pointed at the target. Amplitude comparison monopulse uses a hybrid junction to combine adjacent feeds into sum and difference signals. Phase comparison monopulse compares phase differences between signals from two antennas to determine angular errors.

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