How does a plane manage to dodge radars and other tracking devices?

The incident of MH370 still remains fresh in our minds. How did the plane dodge all the radar? How come the radars were not able to trace the aircraft?
A question arises in your mind then. Can an aircraft really dodge the radars?
You might have often heard of stealth technology. Lets see what that really means and how can an airplane or a jet be invisible to radars?

The fact:

Prior we know how how stealth technology works, we must know how the radar really works. The RADAR ( RAdio Detection And Ranging ) as the acronym suggests works in the range of radio frequency. The radar emits a beam of radio waves which when hits an objects reflects back. This reflected beam is detected by the radar and the object is also detected by knowing the direction in which the beam has been reflected.

So now you would be getting an idea how to "hide" from a radar. There are several ways to remain undetected by the radar. The most possible methods you must have guessed is given below:

• ---> To jam the radar signal
• ---> To pass the radio signal by bending it.
• ---> To absorb the radio signal by using radio wave absorbent material.
• ---> To introduce electromagnetic disturbance in the air.

To jam the radar, we can introduce electronic countermeasures commonly known as ECM. It is not one technology but many technologies combined together to form the overall stealth technology. Initially the airplanes were made of hexagonal glass such that the incoming radio waves get deflected over the plane and does not reflect back to the radar in the ground station. Added to this radar absorbent materials were also added to make it more effective. Later on, with improvement in the technology, the idea changed to modifying the aerodynamics of the jets rather than to jam the radars.

Note:

Even though the stealth jets are passively detected by the radars they are slow and unstable due to the constraints involved.
If they travel at high speeds then it would create a sonic boom and this would be detected by sonar. It becomes aerodynamically unstable due to its design for low detection. Each time its yaw,roll and pitch angles has to be corrected to maintain a stable flight.