Adaptive Active Phased Array Radars Seminar Report Pdf
This ECE Seminar Topic on Adaptive Active Array Phased Multifunction Radars, discuss about features and implementation of Radars. Over the years radar systems have been changing on account of the requirements caused by Increase in the number of wanted and unwanted targets, reduction in target size either due to physical size reduction due to the adoption of stealth measures, the need to detect unwanted targets in even more sever levels of clutter and at longer ranges, 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 full fill a specific role, or by providing user selectable roles within a single radar.
Download ECE Seminar Report on Adaptive Active Phased Array Multifunction Radars.We have been seeing images of radars on TV and magazines, so what does 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.
Typically surveillance radar will produce a fan shaped beam with a fixed elevation illumination profile, the azimuth scanning being achieved by rotating the antenna. A tracking radar will have a pencil beam that is used to track targets by the use of a mechanical tracking mount. Because of the limitations imposed on such radars by their design such radars are “single-function radars”.
The second category of radars is the passive phased array. These incorporate electronic beam scanning or beam shaping by the use of phase shifters, switching elements or frequency scanning methods. These features enable the radar designer to implement more complex systems having the capability to carry out more than one radar functions. “multi function radars”. Generally however, the functions of the radars are pre-programmed and not adaptable as the radar environment or the threat changes. In order to improve the multifunction capability over that of a conventional phased array, in many cases the adaptive active phased array radar (AAPAR) is the only practical solution.
In the AAPAR, transmitter /receiver modules are mounted at the antenna face and adaptive beam forming and radar management and control techniques are used. 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 changes 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 are well known and standard techniques of varying effectiveness have been developed for conventional radars to deal with these effects. Over the years, the design of ECM systems has become much more effective and radars have had to become more sophisticated in order to counter them. As in the case of natural clutter, the methods used to defeat ECM have usually been provided as a series of predetermined functions.
It has not proved possible to adapt the radar parameters quickly to cope with the changing ECM environment In the short term, conventional radar parameters cannot easily be adapted as the ECM threat changes through out a mission. In the longer term the radar design needs to be constantly updated to cope with the change of types and number of ECM equipments.
ADAPTIVE ACTIVE PHASED-ARRAY RADAR ACTIVE ARRAYS A major reason for the large size and power requirements of a conventional phased array radar is the need to overcome the loss in their RF signal between the bulk transmitter and the antenna, and between the antenna and the receiver. Losses typically can be 7dB and in some compiled designs can reach as much as 10dB.
Typically 95% of the prime power and 80% of the effective transmitter power is lost, with only 20% being used for detection. Combining in space the power of many low power radiating modules, mounted on the antenna face as in the AAPAR, ensures that the power is radiated directly into space with minimum loss. If the same module are used for reception with a low noise amplifier (LNA) stage closed to the array face, then similar reduction in receiver losses are obtained. This gives active arrays a major benefits in pure detection performance. Prime power requirements are also greatly reduced, allowing the use of smaller generators in mobile systems and reducing power consumption costs in static systems.
ADAPTIVE RADAR FEATURES The use of active modules provides the ability to control the radiation and receiver parameters of an active array radar in real time and to adapt these as the threat changes. Adaptive radar features are added to an active array to produce an AAPAR features that can be adapted include:. Digital beam forming. Waveform generation and selection. Beam management.
Frequency selection. Task scheduling. Tracking The increase in performance of an active array radar within the environment and its improved detection performance over conventional radars make the active array radar highly versatile and flexible in operation. It is now possible to design a radar to react to changes in the threat scenarios and to adapt its own parameters to optimize performance. The AAPAR can provide many benefits in meeting the performance that will be required by tomorrow’s radar systems.
In some cases it will be the only possible solution. It provides the radar system designer with an almost infinite range of possibilities. This flexibility, however, needs to be treated with caution: the complexity of the system must not be allowed to grow such that it becomes uncontrolled and unstable. The AAPAR breaks down the conventional walls between the traditional systems elements- antenna, transmitter, receiver etc-such that the AAPAR design must be treated holistically. Strict requirements on the integrity of the system must be enforced. Rigorous techniques must be used to ensure that the overall flow down of requirements from top level is achieved and that testability of the requirements can be demonstrated under both quiescent and adaptive condition.
Adaptive Active Phased Array Radars
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