Md Jahedul Islam

Radar (Radio Detecting and Ranging) is a remarkable instrument combining science and technology. Radar transmits strong, high-frequency radio waves (radio waves) in a specific direction. Then an object under those waves, such as a ship or aircraft, actually intercepts these waves, and returns to the radar through reflection.

Through this the radar confirms the presence of the object. Not only the presence the radar can also determine the distance, velocity, angular distance of the incoming object. Radar does this through radio waves. After the radio wave is generated in the radar then the antenna (which acts as a transmitter) shoots the wave forward into space. The radar is always rotating so that it can pick up (receive) reflections from a larger area.

Radio waves emitted by radar travel at the speed of light. It runs until it is interrupted by someone. After intercepting an object the reflected radio waves return to the radar at the speed of light. By receiving this return wave then it is understood how far and in what condition the radio wave returned after being intercepted by the object. That is a detailed understanding of the obstructed object can be obtained from the returning wave. Although the reflected radio wave is quite weak it can be amplified at will. This is why radar can detect distant objects through radiation. With the help of this radar the distant objects can be observed even in thick dark nights.

That's why radar is also known as the third eye of an airplane pilot or a sea captain. We see anything on earth because of light. This light comes from the sun and reflects off objects to reach our eyes. Our brain can easily understand the time of light reflection and the magnitude of light reflection. As a result we can estimate exactly how far away we are from an object. Accordingly we can take action with full understanding about any object. Radar technology operates largely on this basis. On the other hand a radar station, is like a mini-sized radio or television broadcasting station. From this center radio waves are fired into the sky.

The radio waves used in radar are generated by a device called a "Magnetron". Radio waves and light can travel at the same speed. Since the radar uses radio waves there is no problem with the radar whether it is dark at night or bad weather. Apart from the battlefield radar has many uses. Airplane pilots use it when taking off, during takeoff, and during landing.

Also this technology is used to observe weather conditions to know about the surface and properties of distant or nearby. This technology also helps to find out the astronomical objects position of other ships or flat land at sea. Even NASA uses radar to get maps of Earth and other planetary. Some times NASA also uses radar to know the position of satellites. Meanwhile the satellite communication systems and radar technology are complementary to each other. But these two communication technologies are not mutually exclusive.

So excluding one and relying on the other will not provide good information. For example is when a strong cyclone forms at a great distance from a place to strike. Satellite technology communication systems, not radar, will then trace the likely size, shape, and surface location of the cyclone at greater distances. Again when the cyclone comes close to the point of impact it will be tracked by the radar, not the satellite. That is the initial phase will provide satellite information. Later the radar will give detailed information about it.

The two technologies work hand in hand to provide complete information. The light energy emitted by the radar is reflected from the particles of rainwater or combustion vapor and returns to the radar receiver. The larger the water particles or droplets in the cloud then the more reflected electro-magnetic waves that hit them return to the radar and the more energy reflected to the radar. In this way using weather radar the amount of rainfall, the possibility of heavy rain due to thunderstorms and the direction of cyclone flow can be determined.

Basically this radar technology was developed during World War - II. Later this router technology system became one of the most important tools of air warfare in a very short time. Due to the fact that specific positions including the direction of the enemy's warplanes are identified through radar. It is possible to take necessary defense measures accordingly. In case of attack in dark of night or in adverse weather conditions, accurate location guidance of the target is also available from the radar. The role of radar are essential both in attack and defense.

The writer is a, Network Technician (ICT Cell) Jagannath University, Dhaka.