Phased array radar

					Phased array radar
Radar works

?

?

?

?

?

?

?

?

?

?
   Dragonfly's compound eye
   We know that dragonflies of each eye by the many small eyes, each eye can be as
small as a complete, thus making the scope of dragonflies have seen much larger than
the human eye. Similarly, phased array radar antenna array surface by numerous a
radiation unit and receiver unit (known as array element), with cell number and
function of the radar can be from hundreds to tens of thousands. These units are
regularly arranged on a flat surface to form the array antenna. Use of coherent
electromagnetic wave theory, fed through the computer control unit to the current
phase of the radiation, can change the direction of beam scan, so called electronic
scanning. Radiation unit to the received echo signals into the host, to complete the
target of the search radar, tracking and measurement. In addition to the antenna of
each antenna unit oscillator, there are a phase shifter, the device must be. By a
different oscillator phase shifter can be fed into a different phase of the current, and
thus a different direction in space radiation beam. The more the number of antenna
elements, the beam's orientation in space, the more likely. This work is
based on radar controlled phase array antennas, "Phased Array"
was named.
   ?Active phased array radar and passive phased array radar is the difference between
the passive is only a single or several transmitter sub-array of the original can only
receive, and active is the original of each array have the complete transmit and receive
unit!
   ?Advantages of phased array radar:
   ?(1) point to a flexible beam can be fast inertia-free scanning, data rate;
   ?(2) a radar can simultaneously form multiple independent beams, respectively, for
searching, identification, tracking, guidance, passive detection and other functions;
   ?(3) target capacity, while in airspace surveillance, tracking hundreds of targets;
   ?(4) of the complex target environment adaptable;
   ?(5) anti-jamming performance is good. Solid-state phased array radar can * high,
even a small amount of component failure can still work properly.
   ?However, phased array radar equipment, complex, expensive, and the beam
scanning range is limited, the maximum scan angle of 90 ° ~ 120 °. When the need for
comprehensive monitoring, the need to configure the 3 ~ 4 Antenna Array.
   ?Phased array radar, compared with the mechanical scanning radar, scanning more
flexible, performance can *, stronger anti-interference ability, to quickly adapt to
changing battlefield conditions. Multifunction phased array radar has been widely
used in terrestrial remote warning systems, airborne and shipborne air defense
systems, airborne and shipboard systems, emplacement measurement, range
measurements. U.S. "Patriot" air defense system AN/MPQ-53
radar, ship-based "Aegis" Command and Control System radar,
B-1B bomber on the APQ-164 radar, the Russian C-300 air defense weapon system
multifunction radar are all typical of phased array radar. With the development of
microelectronics, solid active phased array radar is widely used, is a new generation
of tactical air defense, surveillance, fire control radar.
   ?How God phased array radar?
   ?"Aegis" is the core of the system with SPY-1D phased array
radar, in particular its superior search capabilities and the ability to identify early
warning, as if to attempt to "independence" of
Taiwan's new leader a straw, a dream of the umbrella, The phased array
radar once again into people's sight. Said phased array radar or technology,
we may be unfamiliar, but if the talk about how China last year, the U.S. military on
the monitoring report of its stealth fighter jet, we may be clear. With a long list of
television receiving antennas to monitor the sky, economic and effective, and this is
the most primitive and based radar, phased array radar.
   ?Here to talk about the radar and phased array radar development.
   ?First, radar and classification
   ?Radar (Radar, or radio detecting and ranging), which means radio search and
ranging. It is the use of various radio positioning methods for detecting, identifying
goals, determination of target coordinates and other information devices. And
production of modern military radar become increasingly important role, especially
World War II, Nazi Germany, the British Air Force and the Air Force's
"Britain" air war, to reveal the importance of the radar very well.
Radar from the antenna system, launcher, receiver, anti-jamming equipment, monitors,
signal processors, power supplies and other components. Among them, the radar
antenna is to achieve a large airspace, multi-function, multi-target one of the key
technologies; signal processor is a multi-function radar with the radar capability of the
core components of many types can be classified several ways:
   ?(1) by positioning methods can be divided into: active radar, semi-active radar and
passive radar.
   ?(2) according to location and can be divided into; ground radar, radar, aviation
radar, satellite and radar.
   ?(3) The type of radiation can be divided into: pulse radar and continuous wave
radar.
   ?(4) The work is divided into a long band: radars, sub radars, centimeter-wave radar
and other band radar.
   ?(5) can be divided according to use: target detection radar, surveillance radar,
weapons control radar, flight security radar, weather radar, navigation radar.
   ?Phased array radar is a new type of active electronic scanning array multifunction
radar. It not only has the functions of conventional radar, but also other RF functions.
Active electronic scanning array of the most important feature of radiation directly to
the air and receive RF energy. It is compared with the mechanical scanning antenna
system, there are many significant advantages. For example, phased array antenna
drive system omitted the whole, some individual components Fasheng failure,
remains high availability * Xing, Mean Guzhangshijian to 100,000 hours, Er
mechanical scanning radar antenna, the mean time to failure Xiaoyu 1000 hours. The
following introduces the advanced phased array radar.
   ?Second, an overview of phased array radar
   ?Phased array technology, as early as the late 30's already there. In 1937,
the United States first began this research. But not until the mid 50's
developed two practical shipboard phased array radar. 60's, the United
States and the former Soviet Union have developed and equipped with several phased
array radar, are used for ballistic missile defense systems, such as the United States
AN/FPS-46, AN/FPS-85, MAR, MSR, the former Soviet Union's
"chicken cage "and" den "and so on.
These are all fixed large phased array radar, the common denominator: the fixed-type
planar array antenna, antenna size, the radiation of high power, role distance. Which
the     United      States   and     the    former     Soviet     Union     AN/FPS-85
"kennel" is the most typical, 70's, phased array radar
has been developed rapidly, in addition to the two US-Soviet foreign, but also the
development of many countries and is equipped with phased array radar, such as
Britain, France, Japan, Italy, Germany and Sweden. The most typical are: the United
States AN/TPN-25, AN/TPQ-37 and GE-592, British AR-3D, France AN/TPN-25,
Japan NPM-510 and J/NPQ-P7, Italy RAT-31S, KR-75, etc. in Germany. This period
of phased array radar has high mobility, small antenna, antenna scanning diversity
system wide application and so on. 80, phased array radar has many unique
advantages as obtained further application. In the equipment and is developing a new
generation of long-range air defense missile weapon systems use multi-function
phased array radar, it has become the third generation, long-range air defense missile
weapon system is an important symbol. Thus, greatly enhanced the combat air
defense missile weapon system performance. In the 21st century, phased array radar
technology with the continuous development and the characteristics of modern
warfare weapons, its manufacturing and research to new levels.
   ?Third, phased array theory
   ?Phased array is composed of many radiating elements arranged in the form of
composition to the antenna array, each unit of radiation energy and the phase between
the relations can be controlled. Typical phased array is the use of computer controlled
phase shifter changes the phase distribution on the antenna aperture to achieve beam
scanning in space, the electronic scanning, referred to as power sweep. Phase control
phase method can be used, real-time method, frequency method, and electronic feed
switch method. In the one-dimensional on a number of radiating elements shall be
arranged in linear array, arranged in two dimensions on the number of units known as
the plane array of radiation. Radiation unit can also be arranged on a curve or surface.
This antenna is called conformal array antennas. Conformal array antenna can
overcome the linear and planar array scan angle and disadvantages, can an electronic
scanning antenna for full airspace. The usual conformal array antenna with circular
array, circular planar array, conical array, cylindrical array, such as hemispherical
array. In conclusion, phased array radar antenna phased its formation its name.
   ?Phased array radar antenna arrays have fairly intensive in the traditional area on
the surface of the radar antenna can be installed more than 1,000 currently to more
than 2000 Phased Array Antenna (F-22 about 2000), any one can send and receive
antenna radar, and several adjacent antenna that has a radar function. Scan, select one
of the blocks (number of antenna elements), or the number of blocks on a single target
or area to scan, so the radar can simultaneously scan many of the goals or region or
track, with multiple radar functions. As a radar can simultaneously scan different
directions, coupled with the scanning electronic control instead of mechanically
rotating, so the information update rate greatly improved mechanical scanning radar is
limited by mechanical rotation frequency and thus the information is updated in
seconds or 10 seconds Level electronic scanning radar was milliseconds, or
microseconds. Thus it is more suitable to deal with high maneuvering targets. In
addition, due to launch a narrow beam, which can also serve as electronic warfare
antennas, such as electromagnetic interference or even the idea of launching
anti-phase radar to detect radio waves off.
   ?Fourth, phased array radar classification
   ?Phased array radar can be roughly divided into two categories, namely, electric
scanning phased array and finite phased array electronic scanning. All electronic scan
phased array can say fixed phased array, that is, in azimuth and elevation are used on
the power sweep, the antenna array is stationary. Limited electronic scan phased array
antenna is a hybrid design, that is to combine two or more antenna technology in
order to obtain the desired effect, with an initial phase scanning technology and
reflector antenna technology combined with the power sweep angle is small, only a
small amount of radioactive elements, so can greatly reduce the equipment cost and
complexity.
   ?Antenna array, according to scan the situation can be divided into phase scanning,
frequency sweep, phase / phase scanning, phase / frequency sweep, machine / phase
scanning, machine / frequency sweep, sweep and other institutions is limited. Phase
scanning series using phase shifters to change the phase relationship to achieve the
beam power sweep. Frequency sweep is to use the method to change the operating
frequency to achieve electronic beam scanning. Phase / phase scanning is the use of
control plane phase shifter array to achieve beam power coordinates of the two angle
sweep. Phase / frequency sweep is the use of phase shifter control plane array and the
other coordinates use a coordinate change of frequency control to achieve the beam
power sweep. Machine / phase sweep is used in the azimuth plane sweep, sweep angle
of elevation on the use phase. Machine / frequency sweep is used in the azimuth plane
sweep, elevation on the use of frequency sweep.
   ?5, the characteristics of phased array radar
   ?Phased array radar possesses great vitality, as it better than the general mechanical
scanning radar. It has the following features:
   ?(1) can deal with multiple objectives. Phased array radar using electronic scanning
flexibility, speed and time division multi-beam theory, can achieve edge search side
track work, and computer matching, can also search for, detect and track in different
directions and different heights of more than grant objectives, and can simultaneously
guided missiles hit more than one multi-targets in the air. Therefore, for
multi-objective, multi-direction, multi-level air combat environment.
   ?(2) multi-functional, mobile. Phased array radar can simultaneously control the
formation of multiple independent beams, respectively, for the implementation of
search, detection, identification, tracking, target illumination and tracking, guided
missiles and other functions. A phased array radar can play the role of multiple
dedicated radar, such as the "Patriot" in a multi-function phased
array radar can complete the equivalent of "Hawk" and
"Nike" -2 type 9 Radar function, but also much higher than they
are able to simultaneously deal with multiple objectives. Therefore, we can greatly
reduce the weapon system's equipment, thus improving mobility.
   ?(3) short reaction time, the data rate. Phased array radar antenna drive system may
not need, beam pointing flexibility, to achieve fast scanning without inertia, thereby
reducing the target signal detection, admission, the time needed for information
transmission, high data rates. Phased array antennas typically digital work to combine
radar and digital computer, can greatly increase the degree of automation to simplify
radar operation, shorter target search, tracking and control and launch preparation
time, facilitate fast and accurate implementation of the plot up procedures and data
processing. Thus improve the tracking of air high-speed maneuvering targets.
   ?(4) anti-jamming capability. Phased array radar antenna aperture distribution can
be used on multiple units together into a very high radiation power, and to rational
management of energy and control of the main lobe gain, according to the needs of
different directions with different distribution of emission energy, easy to implement
adaptive side lobe suppression and adaptive anti-kinds of interference, to facilitate the
detection of small radar reflection from targets and surface targets (such as stealth
aircraft), can also improve the ability of anti-radiation missiles.
   ?(5) high reliability. Phased array radar array group more, and the parallel use, even
a small amount of component failure, can still work, suddenly the possibility of
complete failure of the minimum. In addition, with the development of solid-state
devices, solid-state radar grid more and more devices, and even children have
produced solid-state phased array radar, such as the United States.
"Patriot" radar, its antenna MTBF up to 150,000 hours, even if
10% of cell damage does not affect the normal operation of the radar.
   ?Of course, phased array radar is not perfect, also has its drawbacks. Mainly cost of
your typical phased array radar radar than the average cost to be higher than the
number of times. In addition, phased array radar for the short-range ballistic missile
attacks can be said to do nothing, which is why the United States and Taiwan worried
about the deployment of the mainland coastal areas in Fujian Dongfeng missile
reasons. The 1991 Gulf War, Iraq, of "Scud" missile attacks on
Israel, when the "Patriot" missile could not effectively be shot
down, not to mention it just the Taiwan Strait?
   ?Active phased array radar and passive phased array radar, the difference between
   ?Passive is the only difference is a single or several transmitter sub-array of the
original can only receive, and active is the original of each array have the complete
transmit and receive unit! Airborne radar has experienced in form from the
mechanical scanning phased array electronic scanning, to the latest conformal
"Smart Skin" antenna development, the use of electronic
scanning radar, the advantage in combat where? The future integrated RF (RF) sensor
systems and key technologies of the general characteristics of what?
   ?Nearly 50 years, airborne radar adopting new technological achievements,
improving performance, which are all important to the multi-pulse radio frequency
(MPRF) mode and high-resolution Doppler beam sharpening (DBS) technology in
Radar practical application. Currently, due to signal processing and GaAs microwave
integrated circuits technology, radar, tactical aircraft, as the status of the primary
sensor will still continue. The emergence of active ESA is another technology
advancement. Each of its element in the array has a RF transmitter and sensitive RF
receiver, in each transmit / receive (T / R) module has a power amplifier, a low noise
amplifier and the use of GaAs technology manufacturing phase-amplitude control
device. Active ESA radar technology to give up the traditional center-type high-power
transmitters, in addition to passive phased array radar has the advantage, but also
improve the energy efficiency and the use of adaptive beam control, strong
anti-interference capability and high availability * of advantages.
   ?The first generation of Western countries, active phased array radar system close
to the shape of the United States and Japan, equipped with F-22 FS-X radar
equipment. Britain, France and Germany jointly developed AMSAR project also
identified the use of advanced active phased array radar technology, for follow-up
fighter radar in Europe to prepare for the upgrade modifications. From
today's point of view, the future of radar technology development under the
direction of a shape-preserving "smart skin" array, which the
ESA technology and multi-active aperture sharing combines RF, antenna array
arrangement, and the structure of the aircraft fuselage with skillfully to achieve
wide-band and multi-functional. Conformal antenna array with high-performance
processor and use the space - time adaptive processing techniques to effectively
suppress the external noise, interference and clutter, and in the most optimal way to
detect targets of interest. Although there are many related technical problems to
resolve, but the conformal "smart skin" technology is not a
practical solution, expected to be 20 to 25 years can be reached a practical stage
within.
   ?10 to 15 years, on tactical aircraft radio frequency sensors (including radar) future
tasks, the most urgent need is to increase functionality, improve performance, and also
to focus on the economy and maintainability. America's "Gem
Road" program has proven avionics systems through the use of common
modules, resource sharing and the sensor space reconstruction (reconstruction of
equipment, including radar, electronic warfare and communications - Navigation -
recognition, radio frequency sensors) can make the system the cost and weight
reduced by half, and can * of triple. It has established an integrated modular avionics
design principles have been integrated for the JSF aircraft sensor system (ISS) and
multiple integrated RF sensor design of the project, the European aircraft similar
tactics for the future integrated RF sensor projects being implemented

				
DOCUMENT INFO