Weather Radars

By Local Weather Doppler Radar / On / In Doppler Radar

The word RADAR actively means, RAdio Detecting And Ranging based on its use of what are known as radio waves.

The weather radar has four basic main components.

• A transmitter which is used to create the electromagnetic pulse. • A transmit and receive switch which functions by instructing the antenna used by the radar when to receive pulses.
• The antenna used in sending and receiving the radio pulses.
• A receiver which is used to detect, amplify and decode the signals to a format easily understood by the operator.

The radar antenna which can generally be seen rotating at any given instance emits a series of extremely short radio waves in small bursts which are referred to as pulses.

The duration of each pulse emitted from the radar’s antenna lasts for approximately 0.000001576 seconds or 1.57 times ten to the minus 6 with an in-between listening period of about 0.00099840 seconds or 998.4 times 10 to the minus 6. With such short bursts the waves transmitted from the weather radar through the atmosphere can be seen traveling at the speed of light.

The device by successfully recording the direction in which it’s antenna was aligned allows the radar to effectively determine and monitor the distance and direction of its target. As the target is seen to increase in its effectiveness to reflect the radio waves emitted, would suggest an increase in size such as could be seen in much larger rain drops or in some instances the presence of hail stones. Such reflected radio waves are termed as echoes from the target source.

The information received, monitored and decoded by the weather antenna during the short listening time of 0.001 second is repeated consecutively up to at least 1,300 times per second. The weather radar by monitoring the time allowed for the radio waves to be emitted from its antenna reach its designated target and return allows the radar to effectively calculate the distance from of the target and even its direction.

The Weather Surveillance Radar 88 Doppler or WSR-88D for short generates pulses with an average power capacity of over 450,000 watts when compared to the typical home microwave which is seen at any given occasion to generate a capacity of at least 1000 watts of energy.

Due to the fact that the weather radar will transmit for only a short time and considering that the pulses are calculated only during those transmitted times on an hourly basis, the radar will remain on for just over 6 seconds within each hour. Thus the weather radar will spend the remaining fifty nine minutes and fifty four seconds actively listening for reflected signals to determine the distance, size and motion of possible targets.