Modul 6 antenna & related equipments

GSM-GPRS Operation
Antenna And Equipment
Related
Module 6

2
Outline
 Base station antenna
specification and
meanings
 Antenna types and
trends
 Antenna Type And
Developments
 Other Elements
kris.sujatmoko@gmail.com

3
BTS Logic Structure
BSC
Baseband
subsystem
Power supply
subsystem
RF
subsystem
Abis
interface
Um
interface
MS
Antenna & feeder
subsystem
-48V/+24V

4
Antennas
Categories
Omnidirectional antennas
 radiation patterns is constant in the
horizontal plain
 useful in flat rural areas
Directional antennas
 concentrate main energy into certain
direction
 larger communication range
 useful in cities, urban areas, sectorised
sites

5
RF Antenna and Feeder
Sector¦A
Sector¦A
Sector¦A
Antenna
Feeder
Jumper
Jumper
BTS cabinet
Inner
cable
TX/RX
MANT
RXD

6
Antennas - Antenna Gain
 Measures the antenna´s capability to transmit/extract energy
to/from the propagation medium (air)
 dB over isotropic antenna (dBi)
 dB over dipole (dBd)
 Antenna gain depends on
 mechanical size: A
 effective antenna aperture area: w
 frequency band
 Antenna Gain:
G A w=
4
2
π
λ
Pt
Gain
(Dbi)
Isotropic radiated Power
Equivalent isotropic
radiated power:
EIRP = Pt+Gain(Dbi)
radiated
power

7
Technical Data
B l a h b l a h
b la h b l a h

8
Antenna Properties
Electrical properties
 Operation Frequency Band
 Input impedance
 VSWR
 Polarization
 Gain
 Radiation Pattern
 Horizontal/Vertical beamwidth
 Downtilt
 Front/back ratio
 Sidelobe suppression and null
filling
 Power capability
 3rd order Intermodulation
 Insulation
Mechanical properties
 Size
 Weight
 Radome material
 Appearance and color
 Working temperature
 Storage termperature
 Windload
 Connector types
 Package Size
 Lightening

GSM-GPRS Operation
Antenna Electrical
properties

10
Wavelength
1/2 Wavelength
1/4 Wavelength
1/4 Wavelength
1/2 Wavelength
Dipole
Dipoles
1800MHz 166mm
900MHz 333mm

11
1 dipole (received power) 1mW
Multiple dipole matrix
Received power 4 mW
GAIN = 10log(4mW/1mW) = 6dBd

12
Gain = 10log(8mW/1mW) = 9dBi
“Sector antenna”
Received power 8mW
“Omnidirectional array”
Received power 1mW
(Overlook
Antenna

13
 GSM 900 : 890-960MHz
 GSM 1800 : 1710-1880MHz
 GSM dual band : 890-960MHz &
1710-1880MHz
 eg.824-960MHz 1710-1900MHz
 CDMA2000 1x
Frequency Range

14
Impedance
 50Ω
Cable
50 ohms
Antenna
50 ohms

15
9.5 W
80
ohms
50 ohms
Forward: 10W
Backward: 0.5W
Return Loss 10log(10/0.5) = 13dB
VSWR (Voltage Standing Wave Ratio)
VSWR

16
 <1.5
 Γ=(VSWR-1)/(VSWR+1)
 RL=-20lg Γ

17
Polarization
Vertical Horizontal
+ 45degree slant - 45degree slant

18
V/H (Vertical/Horizontal) Slant (+/- 45°)

19
 Linear,vertical
 ±45 °dual linear ±45 ° slant

20
Dipole
Ideal radiating dot source
(lossless radiator)
eg: 0dBd = 2.15dBi
dBd and dBi
2.15dB

21
Pattern

22
Beamwidth
120° (eg)
Peak
Peak - 10dB
Peak - 10dB
10dB Beamwidth
60° (eg) Peak
Peak - 3dB
Peak - 3dB
3dB Beamwidth

23
3dB Beamwidth Horizontal
 Directional Antenna 65°/90°/105°/120 °Omni 360°

24
Directional Omni-directional
3dB Beamwidth Vertical

25
 Mechanical down tilt
 Fixed electronic down tilt
 Adjustable electronic down
tilt
Downtilt

26
Demonstration of Electronic Downtilt

27
Non down tilt Electronic downtilt Mechanical
downtilt

28
Electronic and mechanical downtilt

29
Antenna Downtilit – Whats goal ?

30
Antenna Downtilt Consideration

31
 Ratio of maximum
mainlobe to maximum
sidelobe
F/B = 10 log(FP/BP) typically 25dB
Back power Front power
Front to back ratio

32
Upper Side lobes Suppression & Null Fill

33
Sidelobes
(dB)
(dB)

35
 Continuous :25-1500 watts
 peak :n2
×p
Permitted Power

36
 IMD@2×43dBm
 f1, f2, 2f1-f2, 2f2-f1
913MHz,936MHz,959MHz,982MHz
Third Order Intermodulation

37
Intermodulation
 Intermodulasi
 Terjadi akibat penguatan
sistem yang non linier
 Hanya orde ke-3 dan
kadang-kadang orde ke-5
yang signifikan
 Sinyal dengan amplituda
yang sama menghasilkan
level IM yang sama pada
frek tinggi dan rendah
 Sinyal dengan amplituda
berbeda memberikan
level IM yang berbeda
pula
 Untuk mencegah
intermodulasi,penguat
dioperasikan pada
penguatan bukan-
maksimum

38
Intermodulation
 Intermodulasi
 Komp. Orde 1 :
diharapkan linier
 Komp. Orde 2 : frek 2ω
 diredam oleh filter
 Komp. Orde 3 : frek 3ω
 diredam dengan
filter
Penguat
Non-linier
( )
( )tB
tAv
B
Ai
ω
ω
cos
cos
+
=
++
+=
3
2
i
iio
cv
bvavv
 Yang bermasalah :
 Komponen yang lain 
amplituda kecil
( ) ( )ABBA ωωωω −− 2,2

39
1000mW ( 1W) 1mW
10log(1000mW/1mW) = 30dB
Isolation

40
10 Simple Guidelines for RF Safety
 All personnel should have EME awareness training
 All personnel entering the site must be authorized
 Obey all posted signs
 Assume all antennas are active
 Before working on antennas, notify owners and disable appropriate
transmitters
 Maintain minimum 3 feet clearance from all antennas
 Do not step in front of antennas
 Use personal RF monitors while working near antennas
 Never operate transmitters without shields during normal operation
 Do not operate base station antennas inside equipment rooms

41
 PVC, Fiberglass
 Anti-temperature, water-proof,
anti-aging, weather resistant
Radome Material

42
 Good-looking,
environment-
protecting
Colour

GSM-GPRS Operation
Antenna Types and Development

45
Antenna Types
By frequency band: GSM900, GSM1800, GSM900/1800
By polarization: Vertical, Horizontal, ±45º linear
polarization, circle polarization
By pattern: Omni-directional, directional
By down-tilt: Non, mechanical, electronic
adjustment, remote control
By function: Transmission, receiving, transceiving

46
Broad band
Multifunctional
High Integrity
Antenna Development Trend

47
 def = Attenuation
between TX & RX
antenna connectors
 Horizontal separation
 needs approx. 5λ distance
for sufficient decoupling
 antenna patterns
superimposed if distance
too close
 Vertical separation
 distance of 1 λ provides
good decoupling values
 good for RX /TX decoupling
 Minimum coupling loss
main lobe
5 .. 10 λ
1λ
Antennas
Decoupling

48
Installation Examples
 Recommended decoupling
 TX - TX: ~20dB
 TX - RX: ~40dB
 Horizontal decoupling distance depends on
 antenna gain
 horizontal rad. pattern
 Omnidirectional antennas
 RX + TX with vertical separation (“Bajonett”)
 RX, RX div. , TX with vertical separation (“fork”)
Vertical decoupling is much more effective
0,2m

49
•Time diversity
•Frequency diversity
•Space diversity
•Polarisation diversity
•Multipath diversity
•interleaving
•frequency hopping
•multiple antennas
•crosspolar antennas
•equaliser
•rake receiver
t
f
Diversity
Diversity Technics

50
Diversity gain depends on environment
Is there coverage improvement by diversity ?
 antenna diversity
 equivalent to 5dB more signal strength
 more path loss acceptable in link budget
 higher coverage range
R
R(div) ~ 1,3 R
A 1,7 A ??
70% more coverage per cell ??
needs less cells in total ??
True only (in theory) if the
environment is infinitely large and
flat
Diversity
Coverage Improvement?

51
Network Elements
MHA
MastHead Amplifier
(Low Noise
Amplifier)
 RX signal amplified
near the antenna in the
top of the mast
 Offers better coverage
 Eliminates the antenna
cable loss
 Increased receiver
sensitivity of the BTS
and cell size
 Increased network
quality
Noise Figure £ 2.0 dB (typical)
RX Gain: Up to 12 dB
Dimensions : 266 x 130 x 123 mm
Weight : 5.6 kg (duplexed)
Volume : 4.2 l
IP 65 Enclosure Protection
Power Feeding Through Antenna Coax
Alarms handled in BTS

52
Booster
• TX signal amplified
• Nokia Booster Configuration
• Booster (PA) Unit (TBU)
• Booster Filtering Unit (AFH)
• Masthead Preamplifier equipment (MHA)
• Output power before combining can be up to 49 dBm
 Isolator + combiner + filter (AFH) give roughly 2.5 dB losses
 Booster BTS is suitable for all the environments where
enhanced coverage or high output power is needed
 Theoretically, cell radius is enhanced up to 60% and the
coverage area is roughly the triple
Network Elements
Booster
TRXTBUAFH

53
BTS Equipments layout
TOWER
BTSE
RECTIFIER
BATTERY
TRANSMISSION EQP.
SITE
GENSET
A
C
Grounding
sensor
ACPDB
Power PLN
SHELTER

GSM-GPRS Operation
End of Section 6
Antenna And Equipment Related

Modul 6 antenna & related equipments

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