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Microwave Systems
Microwave Engineering CHO, Yong Heui
Microwave Engineering
EM Wave Lab 2
1. Microwave Systems
Transmission
Information
- Channel bandwidth
- Base band
- Inefficient wave radiation
Modulation – center frequency
Time domain Frequency domain
출처: RFDH.com
Microwave Engineering
EM Wave Lab 3
Why’s modulation need?
Transmission efficiency
- Multiplexing
- Antenna length: wavelength
- Wave radiation: comparison with DC
Battery: DC Antenna: AC
1. Microwave Systems
Microwave Engineering
EM Wave Lab 4
Friis power transmission formula
Microwave radio link
R
tP rP
1. Microwave Systems
Microwave Engineering
EM Wave Lab 5
Friis power transmission formula
Power density:
Antenna gain: anisotropic radiation (G > 1)
isotropic radiation (G = 1)
Radiation pattern [dBi]: dB isotropic
2
2/
4mWG
R
PS t
t
1. Microwave Systems
Microwave Engineering
EM Wave Lab 6
Friis power transmission formula
Received power:
Effective area
-
er SAP
4
2
re
GA
WR
GGP
Prt
t
r
2
4
Friis transmission formula
1. Microwave Systems
Microwave Engineering
EM Wave Lab 7
Microwave transmitter (Tx)
Up-conversion: frequency
)cos()cos(2
1)cos()cos( yxyxyx
BBf BBLO ff BBLO ff
1. Microwave Systems
출처: RFDH.com
Microwave Engineering
EM Wave Lab 8
Microwave receiver (Rx)
Down-conversion: frequency
)cos()cos(2
1)cos()cos( yxyxyx
BBfBBIF ff BBLO ff
IFLO fff IFff
1. Microwave Systems
출처: RFDH.com
Microwave Engineering
EM Wave Lab 9
Microwave transceiver
Duplexer: bandpass filter or switch
- Loss, tx suppression, channel selection
IF: superheterodyne No IF: direct conversion
1. Microwave Systems
출처: RFDH.com
Microwave Engineering
EM Wave Lab 10
0.6
dishdiameter 4
]GHz[14
]W[100
m
f
P
u
t
0.55
2
]GHz[12
]W[10
3dB
θ
f
P
d
t
Uplink and downlink
][000,40 kmR
1. Microwave Systems
Microwave Engineering
EM Wave Lab 11
tt
et
tt
DG
AD
GP
2
4
EIRP
Uplink calculation
rr
r
DG
D
21
4
2
FS
4
RL
]dB[EIRP FS rr GLP
1. Microwave Systems
Microwave Engineering
EM Wave Lab 12
rr
r
DG
AD
max2
4
Downlink calculation
tt
t
tt
DG
D
GP
21
4
EIRP
2
FS
4
RL
]dB[EIRP FS rr GLP
1. Microwave Systems
Microwave Engineering
EM Wave Lab 13
Noise power
Thermal noise: white noise, Nyquist formula
Thermal Noise or Johnson Noise
BNN
kTBPn
0
Noise temperature
kB
NT
1. Microwave Systems
Microwave Engineering
EM Wave Lab 14
Carrier to noise ratio
TkB
C
BN
C
N
C
0
C/No: related to carrier to noise ratio
G/T: Figure of merit
Carrier to noise ratio
]dB[EIRP FS rGLC
G/T: sensitivity of receiver
1. Microwave Systems
Microwave Engineering
EM Wave Lab 15
Multiplexing: resources
FDM (Frequency Division Multiplexing)
TDM (Time Division Multiplexing)
CDM (Code Division Multiplexing)
1. Microwave Systems
Communication
Microwave Engineering
EM Wave Lab 16
FDMA (FDM Access)
1. Microwave Systems
Resource: frequency
Guard band
Simple transceiver
Interference
Microwave Engineering
EM Wave Lab 17
1. Microwave Systems
TDMA (TDM Access)
Resource:
time
Guard time
Complicated
transceiver
GSM: Global System for Mobile commo
Microwave Engineering
EM Wave Lab 18
FH(Frequency Hopping)-CDMA
1. Microwave Systems
Resource: code
Precise clock
Very complicated transceiver
Bluetooth, military applications
Microwave Engineering
EM Wave Lab 19
DS(Direct Sequence)-CDMA
1. Microwave Systems
QPSK: Quadrature Phase Shift Keying
Microwave Engineering
EM Wave Lab 20
Frequency spectrum
Name Frequency[Hz] Wavelength Application
EHF 30G-300G 1cm-1mm Car radar
SHF 3G-30G 10cm-1cm Radar, satellite
UHF 300M-3G 1m-10cm TV, PCS, IMT2000
VHF 30M-300M 10m-1m FM, TV
HF 3M-30M 100m-10m Shortwave AM, HAM
MF 300k-3M 1km-100m AM
LF 30k-300k 10km-1km Navigation
VLF 3k-30k 100km-10km Submarine, navigation
ELF 30-300 10000km-1000km Submarine
2. Applications
Microwave Engineering
EM Wave Lab 21
Attenuation
2. Applications
Attenuation by water and oxygen HF application
Microwave Engineering
EM Wave Lab 22
ELF application
Skin depth: long wavelength
Long antenna: 104km at USA
Unidirectional communication
Slow bit rate: redundancy
Information: code table
12
2. Applications
Microwave Engineering
EM Wave Lab 23
EHF application
Short antenna
Absorption: air, water(60 GHz)
Anti-collision radar: 76 GHz
ITS: Intelligent Transport System
Radar ITS
2. Applications