High Gain Antenna
-
Upload
yong-heui-cho -
Category
Technology
-
view
900 -
download
0
description
Transcript of High Gain Antenna
High Gain Antenna
Antenna Antenna EngineeringEngineering
CHO, Yong HeuiCHO, Yong Heui
Antenna Antenna EngineeringEngineering
EM Wave LabEM Wave Lab2
Introduction
1. Yagi antenna
Yagi-Uda antenna: parasitic array 1926 at Tohoku University, Japan End-fire traveling-wave antenna
Yagi antenna: one source
Antenna Antenna EngineeringEngineering
EM Wave LabEM Wave Lab3
Operational principle
1. Yagi antenna
Reflector, driver, and director Input impedance: capacitive or inductive loading Gain: about 10 dBi
)()( ziLjzv
)()( ziC
jzv
)()( zAjzE zz
Antenna Antenna EngineeringEngineering
EM Wave LabEM Wave Lab4
Introduction
2. Traveling wave
Traveling-wave long wire antenna Beverage antenna (wave antenna): Harold H.
Beverage in 1922 Traveling-wave vee antenna Rhombic antenna
Antenna Antenna EngineeringEngineering
EM Wave LabEM Wave Lab5
Radiation pattern
2. Traveling wave
Input impedance: almost real Traveling wave: surface wave and leaky wave
Rhombic antenna
zjmeIzI )(
)(sin)( fF
)()()(2/.
2/
cos LfIzdezIf m
L
L
zjk
2/cos
2/cossin)(
Lk
Lkf
Antenna Antenna EngineeringEngineering
EM Wave LabEM Wave Lab6
Introduction
3. Aperture antenna
Horn antenna: sectoral horn, pyramidal horn, conical horn
Antenna Antenna EngineeringEngineering
EM Wave LabEM Wave Lab7
4. Reflector antenna
Parabolic antenna
Symmetric mounting- Masking effect: aperture blocking and
diffraction- Spillover: ground noise
Offset mounting- Small antenna: 1 ~ 4 m (diameter)- Spillover: ground noise
Cassegrain mounting- Parabolic and hyperbolic reflectors- Spillover: sky noise
Antenna Antenna EngineeringEngineering
EM Wave LabEM Wave Lab8
4. Reflector antenna
Cassegrain antenna
Antenna Antenna EngineeringEngineering
EM Wave LabEM Wave Lab9
Introduction
5. Array antenna
Antenna gain vs. loss- : number of elements- : distance from feeder to element
Array antenna
Nl
dB log3 total2elementarray lNDG Nlm ],/dB[ conductordielectrictotal
DG