Introduction The word “radar” is an acronym derived
The word “radar” is an acronym
derived from the phrase “RAdio Detection And Ranging”, and it is used to
determine the location, size, and speed of the objects with radio waves. Radar
system can be seen that it is shaped around a simple idea, if the working
principle of radar system is detailed: first, the electromagnetic signals that
are traveling at the speed of light, are sent to a target by the transmitter,
and this energy which is carried by radio waves, is transmitted and reflected
off a target, then returned. This reflected signal is called as an echo. The
echo’s power, direction, and return time are very important for the radar
system. The characteristics of the determined target are determined according
to these parameters.
The reflected echo from the
electromagnetic signal transmitted by the radar must be above a certain level. This
level is called the threshold value, and it affects many things, and it even
determines the radar’s operation.
In summary, radar is a system which
operates on simple bases. The simple bases are managed by electromagnetic
waves, and the target position, distance, and characteristics are determined
with this bases.
Radar is an important device
used by people for a time. Radar makes it easy to find the range, angle, or
velocity of objects or determined targets in many areas, or devices. Before the
explain all things, it is useful to look at historical process of the radar and
the timing of its development. The first discovery was to measure distance and
velocity of targets, or objects with using radio waves during the Second World
War. It was designed as a warning system that detects enemy aircraft which cannot
be detected with the eyes.
The history of radar dated back
to experiments by Heinrich Rudolf Hertz in 1886 that showed that radio waves
were reflected by metallic objects, and in 1900 Tesla described a concept for
electromagnetic detection and velocity measurement in an interview, 1. Essentially,
Heinrich Rudolf Hertz proved Maxwell’s theory with his work.
A system using radio waves was
developed to detect solid objects by German physicist Cristian Hülsmeyer. He
invented a telemobiloscope to control traffic on the water, but this measures
the duration of electromagnetic waves rotating by hitting a metal objects
(ship), or targets. Therefore, that it can calculate the range.
The early radar developments
were about to meet military requirements, including surveillance, navigation,
and weapons guidance for ground, sea, air, and space vehicles as described
above. And, now radar enjoys an increasing range of applications, 2. Radar
has important roles in daily life, and it is a common factor that is
encountered in many areas. One of the most area in daily life, is the police
traffic radar. It is used to measure whether or not drivers exceed the speed
limits. Another is the “weather radar” familiar to every viewer of local
television news. The another radar application is found in the air traffic
control systems used to guide commercial aircraft. Finally, it can be seen everywhere
and there are many facilitating that make life in the arena.
Radar can be classified as
follows: a primary radar and secondary radar, which is shown in figure 1.1: a
primary radar operation is focused on the principle of echolocation. A signal
is sent with high frequency by the radar antenna at light speed and expected to
hit the target. The transmitted signals are reflected by the target and then
received by the same radar, and secondary radar works with active answer