Name Mashhour j umah ID202322165 Welcome What is an antenna An antenna is an electrical conductor or system of conductors used for transmission and reception of electromagnetic waves ID: 186106
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Slide1
Fundamental of antenna
Name: Mashhour jumahID:202322165
Welcome Slide2
What is an antenna?An antenna is an electrical conductor or system of conductors used for transmission and reception of electromagnetic
wavesTransmission
radiates electromagnetic energy into space
Reception
collects electromagnetic energy from
spaceSlide3
Antenna Fundamentals3
Radiation PatternsSlide4
Antenna FundamentalsRelationship between antenna gain and effective area G = antenna gain
Ae = effective areaf = carrier frequency
c = speed of light (» 3 ´ 10
8
m/s)
= carrier wavelength
Property of R Struzak
4Slide5
Types of antennaAntenna types: actually there are many types of Antenna and there
some of them:1- A
Yagi antenna,
also known as a
Yagi-Uda array
or simply a Yagi, is a unidirectional antenna commonly used in communications when a frequency is above 10 MHz This type of antenna is popular among Amateur Radio and Citizens Band radio operators. It is used at some surface installations in satellite communications systems.Slide6
Yagi Antenna6Slide7
Type of antenna2 - isotropic antenna
Radiates power equally in all directions3 - Dipole antennas
Half-wave dipole antenna (or Hertz antenna)
Quarter-wave vertical antenna (or Marconi antenna):
The term "Marconi antenna" usually refers to a two part
antenna consisting of a vertical portion and
a "reflective" or "ground" portion
.
4 -Parabolic Reflective Antenna
5-Slot
antennaSlide8
monopole antenna6-monopole antenna: is a radio antenna that is one half of a dipole antenna combined with a right-angle ground plane of considerable length in place of its other half
.Slide9
horn antenna-7 horn antenna: is used for the transmission and reception of microwave signals. It derives its name from the characteristic flared appearance. The flared portion can be square, rectangular, or conical.Slide10
helical antenna- 8- helical antenna is a specialized antenna that emits and responds to electromagnetic filed with rotating (circular)polarization. These antennas are commonly used at earth-based stations in satellite communications systems. This type of antenna is designed for use with an unbalanced feed line such as coaxial
cable.Slide11
Antenna functionsTransmission linePower transport medium - must avoid power reflections, otherwise use matching devices
RadiatorMust radiate efficiently – must be of a size comparable with the half-wavelength ResonatorUnavoidable - for broadband applications resonances must be attenuated Slide12
Reflector antennasReflectors are used to concentrate flux of EM energy radiated/ received, or to change its direction
Usually, they are parabolic (paraboloical). The first parabolic (cylinder) reflector antenna was used by Heinrich Hertz in 1888. Slide13
Reflector antennasLarge reflectors have high gain and directivity Are not easy to fabricateAre not mechanically robust
Typical applications: radio telescopes, satellite telecommunications. Slide14
Planar reflectors Uda-Yagi, Log-periodic antennas
14
d
2d
Intended reflector antenna allows maintaining radio link in non-LOS conditions (avoiding propagation obstacles)
Unintended antennas create interferenceSlide15
15
The antenna with the transmission line is represented by an (The venin) equivalent generator
The receiver is represented by its input impedance as seen from the antenna terminals (i.e. transformed by the transmission line)
V
A
is the (induced by the incident wave) voltage at the antenna terminals determined when the antenna is open circuited
Receiving antenna equivalent circuit
Radio wave
Transm.line
Receiver
Antenna
R
r
jX
A
V
A
jX
L
R
L
R
l
Thevenin equivalentSlide16
Power transferThe maximum power is delivered to (or from) the antenna when the antenna impedance and the impedance of the equivalent generator (or load) are matched
16Slide17
17
Group WorkSlide18
Exercise?
18
ExerciseSlide19
Property of R Struzak
19Slide20
20