1. • Marine radars are used to measure the
bearing and distance of ships to prevent
collision with other ships, to navigate and
BASIC ELECTRONICS
to fix their position at sea when within
range of shore or other fixed references
such as islands ,buoys , and lightships.
TITLE: RADAR AND
ANTENNA Brightness can indicate reflectivity as in this
1960 weather radar image (of Hurricane Abby).
The radar's frequency, pulse form, polarization,
signal processing, and antenna determine what it
can observe.
2. What is radar?
• An object-detection system which
uses electromagnetic waves
specifically radio waves to
determine the range, altitude,
direction, or speed of both moving
and fixed objects such as aircraft,
ships, spacecraft
• Transmits pulses of radio waves
or microwaves which bounce off
any object in their path.
• The object returns a tiny part of
the wave's energy to a dish or
antenna which is usually located
at the same site as the
transmitter.
3. Basic radar operation
• Light waves, radio waves, microwaves, radar waves is
electromagnetic waves.
• Unlike water waves, electromagnetic waves do not require a
medium such as water or air to travel through. They can
travel through a complete vacuum.
• Similar to light waves, radar waves bounce off some objects
and travel through others.
• The simplest mode of radar operation is determining how far
away an object is. The radar unit sends radar waves out
toward the target . The waves hit the target and are reflected
back.
4. • The returning wave is received by the radar
unit and the travel time is registered.
• According to basic principles of physics,
distance is equal to the rate of travel (speed)
multiplied by the time of travel.
• All electromagnetic waves travel at the same
speed in a vacuum—the speed of light which is
186,282 miles (299,727 kilometers) per second.
This speed is reduced by a small amount when
the waves are traveling through air but this
can be calculated.
14. The USES of radar
• Modern uses of radar are highly diverse
including
• air traffic control, radar astronomy, air-
defense systems, antimissile systems like
nautical radars to locate landmarks and
other ships, aircraft anti-collision systems
for ocean-surveillance systems,
meteorological precipitation monitoring,
altimetry and flight-control systems,
guided-missile target-locating systems and
ground-penetrating radar for geological
observations.
• High tech radar systems are associated with
digital signal processing and are capable of
15. • ALTAIR - used to detect and track space objects in
conjunction with ABM testing at the Ronald Reagan
Test Site on Kwajalein Atoll.
» Israeli military radar is typical
of the type of radar used for air
traffic control. The antenna rotates
at a steady rate, sweeping
the local airspace with a narrow
vertical fan-shaped beam, to
detect aircraft at all altitudes.
• This Melbourne base Primary and secondary radar
is used for air traffic control and to observe terminal
area conflicts by VFR local aircraft.
16. WHAT IS ANTENNA?
An electrical device which
converts electric current
into radio waves, and vice
versa.
19. antenna
• Also contain reflective or directive
elements or surfaces not
connected to the transmitter or
receiver, such as parasitic
elements, parabolic reflectors or
horns, which serve to direct the
radio waves into a beam or other
desired radiation pattern.
20. THE HISTORY AND
DEVELOPMENT OF ANTENNA
First experiments
Involved the coupling of
electricity and magnetism and
showed a definitive relationship
was that done by Faraday
somewhere around 1830s
Creating a time-varying
magnetic field, which as a
result (from Maxwell’s
21. The coil acted as a loop antenna
and received the electromagnetic
radiation, which was received
(detected) by the galvanometer-
the work of antenna.
22. First antenna
Built in 1888 by German
physicist Heinrich Hertz in his
pioneering experiments
To prove the existence of
electromagnetic waves predicted by
the theory of James Clerk Maxwell
Developed a wireless
communication system in which he
forced an electrical spark to occur in
the gap of a dipole antenna.
23. He used a loop antenna as
receiver, and observed a similar
disturbance
This was 1886. Hertz
placed dipole antennas at the focal
point of parabolic reflector for both
transmitting and receiving.
24. By 1901, Marconi was sending
information across the Atlantic. For
a transmit antenna, he used several
vertical wires attached to the
ground.
In 1901, Columbia University had an
Experimental Wireless Station
There are several discovered
antennas :
25. Yagi-Uda Antenna (1920s)
It is simple to construct and has a
high gain, typically greater than
10dB
operate in the HF and UHF bands
( about 3MHz to 3GHz)
The Yagi antenna was invented in
Japan done by Shintaro Uda
Presented for the first time in
English by Yagi at America
26.
27. Horn Antenna
(1939)
At UHF (300 MHz-3GHz) and
higher frequencies will achieved
to 140 GHz.
Can range up to 25dB in some
cases
28. Antenna Arrays (1940s)
• Often called a ‘phased array’ is asset of
2 or more antennas
• The signals from the antennas are
combined or processed in order to
achieve improved performance
29. Parabolic reflectors
(late 1940)
Commonly known as satellite dish
antenna
(30-40 dB is common) and low cross
polarization
Huge dishes( which can operate from
150 MHz to 1.5 GHz)
Smaller dish antenna typically operate
between 2-28 GHz
The feed antenna is often a Horn
antenna with a circular aperture
30.
31. Patch Antenna (1970s)
• It printed directly onto a circuit
board.
• low cost, have a low profile and
are easily fabricated
32. PIFA (1980)
The quarter-wavelength Patch
Antenna, which leads into the
Planar Inverted-F antenna (PIFA).
The patch is shorted at the end
Has the same current-voltage
distribution as a half-wave patch
antenna
reduced in size 50%.
33.
34. THE USE OF ANTENNA
• Radio broadcasting
A one-way wireless transmission
over radio wave intended to reach a
wide audience.
The signal types can be
either analog or digital audio.
35. • Broadcast television
A mode of television
broadcasting which does not
involve satellite transmission or cables
which is typically using radio waves
through transmitting and
receiving antennas or television
antenna aerials
36. • Two-way radio
A radio that can
both transmit and receive
(a transceiver), unlike
a broadcast receiver which only
receives content
38. • Cell phone
A device which can make and receive
telephone calls over a radio link whilst
moving around a wide geographic area.
It does so by connecting to a cellular
network provided by a mobile network
operator
39. • Satellite communication
An artificial satellite stationed in
space for the purpose
of telecommunication
They are also used for mobile
applications such as communications to
ships, vehicles, planes and hand-held
terminals, and for TV and
radio broadcasting, for which
application of other technologies
40. • Wireless microphone
A microphone without a physical
cable connecting it directly to the
sound recording or amplifying
equipment with which it is
associated
41. • Wireless computer network
A wireless local area network (WLAN)
links two or more devices using some
wireless distribution method
(typically spread-spectrum or OFDM
radio), and usually providing a
connection through an access point to
the wider internet
