04-05-2013, 12:44 PM
SEMINAR REPORT ADAPTIVE ACTIVE PHASED ARRAY RADAR
[attachment=53425]
ABSTRACT
Adaptive active phased array radars are seen as the vehicle to
address the current requirements for true ‘multifunction’ radars systems.
Their ability to adapt to the enviournment and schedule their tasks in real
time allows them to operate with performance levels well above those that
can be achieved from the conventional radars. Their ability to make
effective use of all the available RF power and to minimize RF losses also
makes them a good candidate for future very long range radars.
INTRODUCTION
Over the years radar systems have been changing on account of
the requirements caused by
a) Increase in the number of wanted and unwanted targets
b) reduction in target size either due to physical size reduction due to the
adoption of stealth measures
c) the need to detect unwanted targets in even more sever levels of
clutter and at longer ranges
d) the need to adapt to a greater number of and more sophisticated types
of electronic counter measures
Radar designers addressed these needs by either designing radars
to fulfill a specific role, or by providing user selectable roles within a single
radar. This process culminated in the fully adaptive radar, which can
automatically react to the operational environment to optimize
performance.
Conventional radars fall into two categories independent of what
functions they perform. The first category has fixed antenna with
centralized transmitters which produces patterns by reflector or passive
array antennas. The beaming being fixed, scanning can only be achieved
by physically moving the antenna.
BACKGROUND
TARGET SIZE
Radar echoing areas have become smaller through practical size
reduction, modern materials and the introduction of stealth techniques. In
parallel with this reduction in target size the effectiveness of weapons
delivery systems has improved substantially. The range at which munitions
can be released has increased. This compounded by the increased speed and
lethality of the modern weapons has led to a commensurate increase in the
range at which the targets need to be detected.
ENVIRONMENTAL CONSIDERATION
Along with changes in target characteristics there has also been a
major change in the radar electromagnetic (EM) environment. This consist
of natural elements- land, sea and whether clutters etc. and man made
elements such as background interference, mutual interference from other
systems and ECM. The effect of natural clutter on radar performance is
well known and standard techniques of varying effectiveness have been
developed for conventional radars to deal with these effects.
VOLUME SURVEILLANCE
The AAPAR can provide a number of operating mode to tailor
surveillance volumes to the system or mission requirements. Energy usage
is optimizes and the probability of target determination is maximized by the
management of radar waveforms and beams. Volume surveillance can be
managed in order to cope with varying threats - lower priority surveillance
tasks can be traded for higher priority tasks such as short range surveillance
or target tracking as the threat scenario changes.
TARGET IDENTIFICATION
Co operative technique use an IFF (Identification: Friend or Foe)
integrated system controlled by a radar. Defending on the role of the radar,
integration of target is performed only when the demanded, or on a
continuous 'Turn and Burn' basis. Selective integration is used to minimize
transmission from the radar to reduce the probability of ESM (Electronic
Surveillance Measures) intercepts and is merely always used when mode 4;
the secure IFF mode, is being used .
Non cooperative technique extract additional data from radar
returns by extracting features and comparing them with information held on
threat date bases. A correlation process is used that finds the best fit to the
data. This method can provide good accuracy in recognizing a target from a
class of targets, or a specific type of targets.
TRACKING OF ECM EMISSIONS
Receive-only beams can be formed with an active array, giving all
the normal receive processes without the need for transmitted RF. Utilizing
these beams, sources of in band radiation can be accurately tracked in two
dimensions. The track data can be correlated with strobes from other
sensors to enable the positions of the jamming sources to be determined
and tracked in conditions in which the presence of jamming may prohibit
the formation of tracks.
KILL ASSESSMENT
It is possible to use a radar sensor to give some information to the
kill assessment process. The radar can only be used in two ways. Firstly, it
can determine whether the trajectory or track vector has changed
sufficiently to indicate that the threat has aborted its mission or been
damaged sufficiently to loose control. Secondly, the radar can form a high
resolution image of the target to determine if it has been fragmented.
[attachment=53425]
ABSTRACT
Adaptive active phased array radars are seen as the vehicle to
address the current requirements for true ‘multifunction’ radars systems.
Their ability to adapt to the enviournment and schedule their tasks in real
time allows them to operate with performance levels well above those that
can be achieved from the conventional radars. Their ability to make
effective use of all the available RF power and to minimize RF losses also
makes them a good candidate for future very long range radars.
INTRODUCTION
Over the years radar systems have been changing on account of
the requirements caused by
a) Increase in the number of wanted and unwanted targets
b) reduction in target size either due to physical size reduction due to the
adoption of stealth measures
c) the need to detect unwanted targets in even more sever levels of
clutter and at longer ranges
d) the need to adapt to a greater number of and more sophisticated types
of electronic counter measures
Radar designers addressed these needs by either designing radars
to fulfill a specific role, or by providing user selectable roles within a single
radar. This process culminated in the fully adaptive radar, which can
automatically react to the operational environment to optimize
performance.
Conventional radars fall into two categories independent of what
functions they perform. The first category has fixed antenna with
centralized transmitters which produces patterns by reflector or passive
array antennas. The beaming being fixed, scanning can only be achieved
by physically moving the antenna.
BACKGROUND
TARGET SIZE
Radar echoing areas have become smaller through practical size
reduction, modern materials and the introduction of stealth techniques. In
parallel with this reduction in target size the effectiveness of weapons
delivery systems has improved substantially. The range at which munitions
can be released has increased. This compounded by the increased speed and
lethality of the modern weapons has led to a commensurate increase in the
range at which the targets need to be detected.
ENVIRONMENTAL CONSIDERATION
Along with changes in target characteristics there has also been a
major change in the radar electromagnetic (EM) environment. This consist
of natural elements- land, sea and whether clutters etc. and man made
elements such as background interference, mutual interference from other
systems and ECM. The effect of natural clutter on radar performance is
well known and standard techniques of varying effectiveness have been
developed for conventional radars to deal with these effects.
VOLUME SURVEILLANCE
The AAPAR can provide a number of operating mode to tailor
surveillance volumes to the system or mission requirements. Energy usage
is optimizes and the probability of target determination is maximized by the
management of radar waveforms and beams. Volume surveillance can be
managed in order to cope with varying threats - lower priority surveillance
tasks can be traded for higher priority tasks such as short range surveillance
or target tracking as the threat scenario changes.
TARGET IDENTIFICATION
Co operative technique use an IFF (Identification: Friend or Foe)
integrated system controlled by a radar. Defending on the role of the radar,
integration of target is performed only when the demanded, or on a
continuous 'Turn and Burn' basis. Selective integration is used to minimize
transmission from the radar to reduce the probability of ESM (Electronic
Surveillance Measures) intercepts and is merely always used when mode 4;
the secure IFF mode, is being used .
Non cooperative technique extract additional data from radar
returns by extracting features and comparing them with information held on
threat date bases. A correlation process is used that finds the best fit to the
data. This method can provide good accuracy in recognizing a target from a
class of targets, or a specific type of targets.
TRACKING OF ECM EMISSIONS
Receive-only beams can be formed with an active array, giving all
the normal receive processes without the need for transmitted RF. Utilizing
these beams, sources of in band radiation can be accurately tracked in two
dimensions. The track data can be correlated with strobes from other
sensors to enable the positions of the jamming sources to be determined
and tracked in conditions in which the presence of jamming may prohibit
the formation of tracks.
KILL ASSESSMENT
It is possible to use a radar sensor to give some information to the
kill assessment process. The radar can only be used in two ways. Firstly, it
can determine whether the trajectory or track vector has changed
sufficiently to indicate that the threat has aborted its mission or been
damaged sufficiently to loose control. Secondly, the radar can form a high
resolution image of the target to determine if it has been fragmented.