RADARS
Radar is a basically a means of gathering information about distant objects or targets by sending electromagnetic(EM) waves to them and thereafter analyzing reflected waves or the echo signals. Radar evolved a few years before World war II. it was a radar that gave birth to microwave technology. in fact the early researchers found out that the highest frequencies gave the most accurate results. higher frequencies produce the best echoes,make it possible to detect smaller targets and permit the use of smaller antennas. a radar can detect static or mobile objects or targets and is the most effective method for guiding a pilot with regard to his location in space and also for warning the approach of an enemy plane for similar purposes.
A radar can detect static or mobile objects or targets and is the most effective method for guiding a pilot with regard to his location in space and also for warning the approach of an enemy plane for similar purposes.
We know that if an electromagnetic wave encounters sudden change in conductivity σ, permittivity ε or permeability μ in the medium, a part medium, a part of the electromagnetic energy gets absorbed by the second medium and is reradiated. This sudden change in the electrical property of the medium constitutes the target.
The reradiated energy on being received back at the radar station gives information about the location of the target.The location of the target includes range,angle and velocity parameters.the range is the distance of the target from radar station.The angle could be azimuth or elevation angle for static targets and velocity for moving targets.
For satisfactory location of the target,the received power(echo power) must be appreciable.
Accordingly,the amount of the power(energy) required to be radiated by the radar transmitter must be tremendous,typically few kW to MW.such high frequencies can be generated using magnetrons.
A radar can detect static or mobile objects or targets and is the most effective method for guiding a pilot with regard to his location in space and also for warning the approach of an enemy plane for similar purposes.
We know that if an electromagnetic wave encounters sudden change in conductivity σ, permittivity ε or permeability μ in the medium, a part medium, a part of the electromagnetic energy gets absorbed by the second medium and is reradiated. This sudden change in the electrical property of the medium constitutes the target.
The reradiated energy on being received back at the radar station gives information about the location of the target.The location of the target includes range,angle and velocity parameters.the range is the distance of the target from radar station.The angle could be azimuth or elevation angle for static targets and velocity for moving targets.
For satisfactory location of the target,the received power(echo power) must be appreciable.
Accordingly,the amount of the power(energy) required to be radiated by the radar transmitter must be tremendous,typically few kW to MW.such high frequencies can be generated using magnetrons.
we know that if an electromagnetic wave encounters sudden change in conductivity ,permittivity or permeability in the medium,a part of the electromagnetic energy gets absorbed by the second medium and is re radiated. this sudden change in the electrical property of the medium constitutes the target.
In general,radars consist of a transmitter, a receiver, a display and antennas. The received echo signal after it is processed by the receiver is displayed on the radar screen.It is very much possible to detect the height,speed and direction of travel of the target by space tringulation and by the time taken for the echo to come back after reflection from the target . the display screen can be similarly calibrated to indicated the target data.
1.The duplexer should be automatic in its operation.
2. The radar transmitter should remain silent during the echo period.
3. The transmitter pulse should be quite powerful to counter the attenuation during forward and return joureneys.
4. The received echo pulse being weak,the receiver should be extermely sensitivity and at the same time immune to noise signals.It should have necessary amplification,signal processing circuitry and capability to display the target information on the radar screen.
5. The radar antenna should be highly directive and have a large gain so that it can radiate a strong signal and receive a weak pulse.
Advantages of a Radar:
In general,radars consist of a transmitter, a receiver, a display and antennas. The received echo signal after it is processed by the receiver is displayed on the radar screen.It is very much possible to detect the height,speed and direction of travel of the target by space tringulation and by the time taken for the echo to come back after reflection from the target . the display screen can be similarly calibrated to indicated the target data.
The general requirement for any radar system are summarised below.
1.The duplexer should be automatic in its operation.
2. The radar transmitter should remain silent during the echo period.
3. The transmitter pulse should be quite powerful to counter the attenuation during forward and return joureneys.
4. The received echo pulse being weak,the receiver should be extermely sensitivity and at the same time immune to noise signals.It should have necessary amplification,signal processing circuitry and capability to display the target information on the radar screen.
5. The radar antenna should be highly directive and have a large gain so that it can radiate a strong signal and receive a weak pulse.
Advantages of a Radar:
i) Radar can see rain,fog,snow , darkness and haze .
ii) Radar can determine the range and angle.
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