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WCDMA RNP Antenna
Citation preview
Antenna SelectionAntenna Selection
Review
Antenna is the interface between a radio transceiver and outside propagation environment. The same set of antenna can both transmit and receive radio waves. When transmitting radio waves, it converts the RF currents into electromagnetic (EM) waves; when receiving radio waves, it converts EM waves into RF currents.
Objectives
Learn the classification of antenna
Know some of characteristics of antenna
Study the principles for antenna selection
Understand the antenna usage at different scenarios
By this course, you will be able to:
Contents
Antenna Classification
Major Technical Performances of the Antenna
Principles for Antenna Type Selection
Antenna Selection for Different Scenarios
Summary
Based on the polarization mode: vertical polarization antennas (also called mono-polarization
antennas) Cross polarization antennas (also called dual polarization
antennas).
Antenna Classification
vertical polarization antenna dual polarization antenna
Antenna Classification
According to the outlines
whip antenna plate antenna cap antenna paraboloid antenna
Contents
Antenna Classification
Major Technical Performances of the Antenna
Principles for Antenna Type Selection
Antenna Selection for Different Scenarios
Summary
Working Bands
in China and Europe UL: 1920 ~ 1980 MHz DL: 2110 ~ 2170 MHz
in North America UL: 1850 ~ 1910 MHz DL: 1930 ~ 1990 MHz
Antenna Gain
Gain is one of the most important indices of an antenna. It indicates the antenna’s capability of centralizing energy to a certain direction
dBi is defined as the energy centralizing capability of the actual directional antenna (including omni antenna) in relation to isotropic antennas, “i” means “isotropic”.
dBd is defined as the energy centralizing capability of the actual directional antenna (including omni antenna) in relation to dipole antennas, “d” means “dipole”.
Antenna Gain
As a passive device, antenna itself cannot increase the energy of transmitted signals. It only can centralize the energy to a certain direction by combining the antenna dipoles and changing their feeding mode
¸ Isotropic
DipoleActual antenna
The actual antenna gain is 11dBi
11dBi
8.85dBd 2.15dBi 2.15dBi ERP
EIRP
Antenna Pattern
The graph describes the distribution of EM field of the antenna transmission along the fixed distance on the angular coordinates is called pattern. A pattern presented by transmission field intensity is called field intensity pattern, a pattern presented by power density is called power density pattern, and a pattern presented by phase is called phase pattern.
Symmetric half-wave dipole Pattern
Top view side view
directional antenna pattern omni antenna pattern
Antenna Pattern
Antenna Pattern
Beam width (BW) (called semi-power angle) Front-to-back ratio Zero-point filling Upper side lobe suppression
Relationship between Wave Width and Gain
Antenna is an energy-centralizing device. The enhancement of transmission in one direction means the reduction of transmission in other directions. In general, we can enhance the transmission strength in a certain direction by reducing the horizontal lobe width so as to increase the antenna gain. Under a given antenna gain, the horizontal BW is in reverse proportion with the vertical BW:
10 lg 32400aG Ga : antenna gain, dBi;B: vertical BW, degree .Θ : horizontal BW, degree.
Polarization Mode
Polarization is the transmission performance describing the vector direction of EM field intensity. Unless specific state, the space direction of electric field vector is the polarization direction of EM wave. The vector direction refers to the direction of maximum transmission of antenna.
Single polarization antennas in WCDMA system adopt vertical polarization, while dual polarization antennas use polarization diversity to minimize the negative effect of multi-path fading in the mobile communication system so as to improve the quality of receiving signals. Dual polarization antennas in WCDMA system usually use
± 45° cross polarization mode.
Mechanical Down Tilt and Electric Down Tilt
Mechanical down tilt
electric down tilt
Voltage Standing Wave Ratio (VSWR)
When the input impedance is not consistent with the characteristic impedance, the reflected wave and the incident wave overlap on the feeder and form standing wave. The ratio between the maximum value and the minimal value of the adjacent voltage is VSWR. Big VSWR leads communications distance shortened, at same time reflection power returns to power amplifier (PA) of transmitter. PA might be damaged.
9.5 W
80 ohms
50 ohms
Forward: 10W
Reflection: 0.5W
Voltage Standing Wave Ratio (VSWR)
If and respectively stand for the input impedance and
nominal impedance of the antenna, the reflectance is
, , where . The matching feature of a
port can also be indicated by Reflection Loss. If
will be 13.98
A oZ
oA
oA
11
VSWR 50oZ
1:5.1VSWR
dBLR ..
Other Technical Performances
Port Isolation Power Capacity Input Interface of the Antenna Passive Inter-modulation (PIM) Antenna Size and Weight Wind Load Working Temperature and Humidity Lightning Protection Three-Proof Capability
Contents
Antenna Classification
Major Technical Performances of the Antenna
Principles for Antenna Type Selection
Antenna Selection for Different Scenarios
Summary
Antenna Working Bands
Outdoor Antennas Both WCDMA and DCS systems simultaneously
1710 ~ 2170 MHz
Only for WCDMA system
1920 ~ 2170 MHz
Indoor Antennas for GSM/DCS/WLAN/WCDMA
800 ~ 2500 MHz
Principle for Antenna Beam Width Selection
Selection of beam width horizontal beam : depends on the type design of NodeB
vertical beam: depends on antenna gain
In urban areas 3-sector vertex-excited NodeBs, 65° horizontal beam width
6-sector vertex-excited NodeBs, 33° horizontal beam width
In suburbs
3-sector center-excited NodeBs, 90° horizontal beam width
Principle for Polarization Mode Selection
open mountainous areas and rural areas.
vertical single polarization antennas
urban area
dual polarization antennas
Principle for Downtilt Mode Selection
Comparison between Mechanical Downtilt and Electric DowntiltComparison between Mechanical Downtilt and Electric Downtilt
Principle for Downtilt Mode Selection
Comparison between Preset Electricity Downtilt and Zero-Point FillingComparison between Preset Electricity Downtilt and Zero-Point Filling
The use of preset electric downtilt can shorten the coverag
e range of the main lobe if the cell coverage is planed to
small.
Through zero-point filling, a kind of shaping technology, w
e can obtain a good pattern. In this case, the upper side lo
be can be suppressed, so this kind of antennas will influen
ce other aspects
Principle for Downtilt Mode Selection
Planning and Optimization of Downtilt AnglePlanning and Optimization of Downtilt Angle
For an omni antenna, we cannot adjust the mechanical do
wntilt angle, but we can select preset electricity downtilt an
gle antennas.
For a directional antenna, in different occasions, requirem
ents for the downtilt angle adjustment range are different.
Principle for Front-to-back Ratio Selection
In occasions where NodeB sites are densely distributed, if
the back lobe is too big, it will be likely to cause pilot polluti
on and the network quality will be influenced. In urban are
as, the antenna front-to-back ratio should be ≥ 25dB. In su
burbs or rural areas, the antenna front-to-back ratio can a
ppropriately lower.
The front-to-back ratio is in reverse proportion to the beam
width. The narrower the beam is, the higher the front-to-ba
ck ratio is.
Principle for Antenna Size Selection
Antenna size selection is mainly related to tAntenna size selection is mainly related to t
he installabilityhe installability
Firstly, the antenna size is related to the tec
hnical level of manufacturers
Secondly, the antenna size is related to the a
ntenna gain
Principle for Antenna Impedance Selection
The input impedance of a combiner is 50Ω. In order to reduce the standing wave ratio, the characteristic impedance of an antenna should match with the input impedance, namely, it should be 50Ω. In general, the characteristic impedance can meet this requirement, but attention should be paid to this index during selection or certification of new antennas.
Contents
Antenna Classification
Major Technical Performances of the Antenna
Principles for Antenna Type Selection
Antenna Selection for Different Scenarios
Summary
Antenna Selection for Different Scenarios
In WCDMA system, antenna selection is of great importance. Antennas should be selected based on the practical situations such as the NodeB design, network coverage requirements and interference conditions.
Practical situations In urban coverage In sub-urban coverage In rural coverage In highway coverage In indoor coverage In offshore coverage In tunnel coverage
In Urban CoverageIn Urban Coverage
Huawei Recommendation
Frequency range: 1710 ~ 2170 MHz/±45°dual polarization / 65°horizontal BW/15 dBi gain/preset 6°electrical DT or 0 ~ 10°adjustable electrical DT and 0 ~ 15° adjustable mechanical DT/upper side lobe suppression and zero-point filling/25dB or higher front-to-back ratio.
Antenna Selection for Different Scenarios
In Suburban CoverageIn Suburban Coverage
Huawei Recommendation:
Select the specific antennas by referring to antenna selection for urban areas and that for rural areas depending
on the distance between two NodeBs.
Antenna Selection for Different Scenarios
In Rural CoverageIn Rural Coverage
Recommendation (for directional antennas): Working freq
uency 1710 ~ 2170 MHz / vertical polarization / 90° horizont
al beam width / 18 dBi antenna gain / without preset downtilt
/ zero-point filling
Recommendation (for omni antennas): Working frequency
1710 ~ 2170 MHz / vertical polarization / 11 dBi antenna gai
n / without preset downtilt / zero-point filling
Antenna Selection for Different Scenarios
In Highway CoverageIn Highway Coverage
Recommendation (for directional antennas): Working freq
uency 1710 ~ 2170 MHz / vertical polarization / 30° horizont
al beam width / 21 dBi antenna gain / without preset downtilt
/ zero-point filling
Recommendation (for 8-figure-shape antennas): Working
frequency 1710 ~ 2170 MHz / vertical polarization / dual 70°
horizontal beam width / 14 dBi antenna gain / without preset
downtilt / zero-point filling
Antenna Selection for Different Scenarios
For Highway CoverageFor Highway Coverage
Recommendation (for heart-shape antennas):
Frequency range: 1710 ~ 2170 MHz/VP/210°horizontal BW/
12 dBi gain/ without preset DT / zero-point filling
S0.5/0.5 NodeB configuration with high-gain directional ante
nnas 8-figure-shape antennas
Antenna Selection for Different Scenarios
In Indoor CoverageIn Indoor Coverage
Recommendation (for omni antennas):
Frequency range: 800 ~ 2500 MHz/vertical polarization
(VP)/360°horizontal BW, 90° vertical BW/2dBi gain.
Recommendation (for plate directional antennas): Frequency range: 800 ~ 2500 MHz/vP/90°horizontal BW,
60°vertical BW/7dBi gain.
Recommendation (for log-periodical antennas):
Frequency range: 800 ~ 2500 MHz/VP/55°horizontal BW,
50° vertical BW/11.5dBi gain.
Antenna Selection for Different Scenarios
In Offshore CoverageIn Offshore Coverage
Antenna Recommended:
frequency range: 1710 ~ 2170 MHz
vertical polarization
30° horizontal BW
gain 21 dBi
without preset DT
zero-point filling
Antenna Selection for Different Scenarios
In Tunnel CoverageIn Tunnel Coverage
Antenna Recommended
Frequency range: 800 ~ 2200 MHz
vertical polarization
55°horizontal BW
log-periodical type with gain 11.5 dBi (consider sharing with GSM/DCS systems).
Leaky cable
Antenna Selection for Different Scenarios
Contents
Antenna Classification
Major Technical Performances of the Antenna
Principles for Antenna Type Selection
Antenna Selection for Different Scenarios
Summary
Summary
This course helps you: To make sure antenna classification To familiarize with performances of antenna To understand the principles of antenna selection To select antenna focusing on specific working
environments