Gbc_008_e1_1 Antenna System: Zte University Gsm-bss Team

GBC_008_E1_1 Antenna System

ZTE University GSM-BSS Team

Objective By the end of this course, you will be able:  To Understand the concept of dipole

 To state GSM antenna specifications  To comprehend the principle of antenna

selection

Content Antenna overview Antenna specifications Principle of antenna selection

Antenna overview

Radio Waves 

A form of electromagnetic radiation typically generated as

disturbances sent out by oscillating charges on a transmitting antenna

Blah blah blah bl ah

Antenna overview

Definition



An Antenna is any

device used to collect or radiate Electromagnetic Waves

Antenna overview

Generation of radio waves DIPOLES Wavelength

1/4 Wavelength 1/2 Wavelength 1/4 Wavelength 1/2 Wavelength Dipole

1800MHz ：166mm 900MHz ：333mm

Antenna overview

Antenna for mobile communication



Linear antennas are used:  Monopole (Slab)  Dipole Elements

• Array of dipoles

• Single Monopole • Patch Antenna Base Tranceiver Station Antenna Mobile Phones

Antenna overview

Antenna basic structure 

Antenna are generally composed of

stacked of dipole bundling their radiated power to form a desired antenna pattern in vertical plains

around the antenna



Depending on the gain desired that wants to be achieved several of those diploes can be arranged on top of one another

Antenna Foundation:Halfwave Dipole Zero current at each end each tiny imaginary “slice” of the antenna does its share of radiating

TX

RX Maximum current at the middle Current induced in receiving antenna is vector sum of contribution of every tiny “slice” of radiating antenna Width of band denotes current magnitude

Antenna Gain

Attention: Antennas are passive devices; they do NOT amplify RF energy. What is antenna gain? On the condition of same input power and same position of space, the ratio between the power radiated from the practical antenna and from the ideal isotropic antenna is called the antenna gain.

Same amount of energy, focussed in a particular direction

Antenna overview

Half wave dipole

1个 dipole

Multiple dipole matrix

Received Power：1mW

Received Power：4 mW

GAIN= 10log(4mW/1mW) = 6dBd

Antenna overview

Isotropic antenna

Antenna (Overlook

“Omnidirectional array” Received power：1mW

“Sector antenna” Received power：8mW

Gain=10log(8mW/1mW) = 9dBi

Antenna overview

dBd and dBi

Ideal radiating dot source (lossless radiator)

2.15dB

0dBd = 2.15dBi

Dipole

Antenna overview

dBd and dBi

ERP and EIRP Reference Antenna 

Effective Radiated Power (ERP and EIRP)  apparent power in a particular direction. It is equal to actual transmitter power times antenna gain in that direction.  Radiated power = Input power x

A

100 W

antenna gain

B

or in dB’ = dBm + dB(i or d) eg:50dBm

+

TX

4.4 dBi

Directional Antenna

TX 100 W

EIRP = 54.4 dBm (right picture) 

ERP is expressed in comparison to a standard radiator  ERP: compared with dipole antenna

EIRP B A (ref)

A B

 EIRP: compared with isotropic antenna

275w

100w

Antenna Gain Example

Antenna Gain = + 18 dBi

EiRP = +39 + 18 = +57 dBm

jumper -0.5dB Ant Input Power = + 39dBm -3dB

jumper

Base Station Transmitter (20 watts)

-0.5dB

+43 dBm

Heliax Cable

Content Antenna overview Antenna specifications Principle of antenna selection

Antenna specifications

Antenna electrical properties 

Operating 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

Antenna specifications

GSM antenna frequency range

Type GSM 900 GSM 1800 GSM Dual Band

Frequency Range 890 1710 890 1710

-

960 MHz 1880 MHz 960 MHz 1880 MHz

Antenna specifications

GSM antenna frequency range

Optimum 1/2 wavelength for dipole at 925MHz

at 890 MHz

at 960 MHz Antenna Dipole

BANDWIDTH = 960 - 890 = 70MHz

Antenna specifications

Impedance



Standard Value: 50

Antenna Cable 50 ohms 50 ohms

Antenna specifications

Voltage standing wave ratio (VSWR)

Forward: 10W 50 ohms Backward: 0.5W

80 ohms

Return Loss： 10log(10/0.5) = 13dB VSWR (Voltage Standing Wave Ratio)

9.5 W

Antenna specifications

Calculation of VSWR



VSWR1.5



 = (VSWR-1)/(VSWR+1)



ReturnLoss = -20lg 

Antenna specifications

Polarization

Vertical

+ 45degree slant

Horizontal

- 45degree slant

Antenna specifications

Space diversity

Antenna specifications

Polarization diversity

V/H (Vertical/Horizontal)

Slant (+/- 45°)

Antenna specifications

Types of antenna

Linear Polarization,vertical

X Polarization, 45

Antenna Radiation Pattern

  

The first basic function of antenna is to radiate energy to outer space. The second basic function is to radiate most of energy to the desired direction. But in fact, the practical radiation is very complex, it is called: “radiation pattern”

Beamwidth 

The radiation pattern has several lobes; the strongest is called the main lobe and the others are side lobes.



From the peak of the main lobe, the radiation will become weaker and weaker as it spreads to the side. The angle between two position which is 3dB below the peak is called beamwidth or halfpower angle.



The narrower the beamwidth, the better of concentration of the radiation and the higher of the gain. 3dB Beamwidth Peak - 3dB

60° (eg)

Peak Peak - 3dB

Horizontal 3dB Beamwidth



Directional Antenna：65°/90°/105°/120 °

Omni：360°

Horizontal 3dB Beamwidth

Typical 90 3dB beamwidth sketch map



20,30 beamwidth antennas are mostly used in narrow areas such as a highway；65 are usually used in city area， 90s are used more in suburbs and countryside.

Vertical 3dB Beamwidth 

48°,33°,15°,8°，are some common values for the vertical 3dB beamwidth.



If the vertical beamwidth is small, then we can control the coverage by adjusting the downtilt. Directional ：

Omni：

Antenna specifications

Bandwidth

3dB Beamwidth

10dB Beamwidth Peak - 3dB

60° (eg)

Peak

Peak - 3dB

Peak - 10dB 120° (eg)

Peak

Peak - 10dB

Antenna specifications

3dBm horizontal beamwidth 

Directional Antenna：65°/90°/105°/120°



Omni：360°

Omni-directional

Directional

Antenna specifications

3dBm vertical beamwidth Omni-directional

Directional

Antenna specifications

Antenna structure types Omni-directional

Directional

Antenna specifications

Antenna down tilt



Mechanical down tilt



Electrical down tilt



Adjustable electronic down tilt

Antenna specifications

Mechanical down tile



It is achieved by physically tilting the antenna out of the perpendicular by using down tilt kit



PROS: Cost efficient and flexible



CON: Has no effect on the side-lobe characteristics of the antenna

Antenna specifications

Electrical down tilt Input Signal



Electrical downtilt can be fixed or adjustable



Fixed is tuned by the manufacturer



Adjustable allows adjustment in a certain level on the rear of the antenna

Antenna specifications

Down tilt

Non down tilt

Electronic downtilt

Mechanical downtilt

Electronic and Mechanical Downtilt

Antenna specifications

Antenna tilt development

Downtilt Adjustment



In general, the original downtilt can be calculated：  θ= arctan (h/R)＋A/2  θ—antenna downtilt  h—antenna height  R—cell coverage radius  A---antenna vertical 3dB beamwidth





In this formula, the main lobe of antenna will point to the edge of cell coverage. Actually, the antenna will often need downtilt adjustment during optimization to ensure the real coverage does not go too far or too near.

Antenna specifications

FRONT-TO-BACK Ratio 

Ratio of maximum mainlobe to maximum sidelobe

Back power

F/B = 10 log(FP/BP)

Front power

typically ： 25dB

Up Sidelobe Restraint 

Usually, the up sidelobe energy is not used. So we perform restraint on the up sidelobe.

UP SIDELOBE (dB)

DOWN SIDELOBE (dB)

Antenna specifications

Upper sidelobe suppression and null fill

Antenna specifications

Upper sidelobe suppression and null fill

Antenna specifications

Intermodulation 

 

It occurs when two signals of a different frequency mix in a nonlinear device It can be a problem at any site that has two or more transmitters It can be caused by a transmitter of the same system or by a transmitter in another site that is co-sited or has a site in the neighborhood

IMD@243dBm

f1, f2, 2f1-f2, 2f2-f1

913 MHz

936 MHz

959 MHz

982 MHz

Permitted Power

• •

Continuous :25-1500watts Depends on the carriers number and the power of the carriers

Antenna specifications

Isolation

10log(1000mW/1mW) = 30dB

1000mW ( 1W)

1mW

Antenna specifications

Antenna mechanical properties 

Size



Weight



Radome material



Appearance and color



Working temperature



Storage temperature



Windload



Connector types



Package Size



Lightning Protection

Antenna specifications

Dimension



LWH  Length：connected with vertical bandwidth and gain  Width：connected with horizontal bandwidth  Height：connected with techniques adopted

Antenna specifications

Weight 

A factor that can affect transport and deployment

Antenna specifications

Radome materials 

PVC, Fiberglass



Anti-temperature, weather resistant

water-proof ， anti-aging ，

Page

Antenna specifications

Color 

Good-looking



Environment-protecting

Antenna specifications

Temperature range 

Operation and storage  Typical range：-40°C

— +70°C

Storage Temperature Range

`

Typical value:

` -40°C

Page

— +70°C

Wind Load

`

Page

Eg: 83N at 160 km/h

Page

Flat Plate Area

`

The smaller the better

Page

Connector Type

` ` ` `

7/16”DIN， N， SMA Female / Male

Page

Antenna specifications

Mast



Mast diameter 45-90mm

Antenna specifications

Lightning protection



Direct Ground

Antenna specifications

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, receiver, transceiver

Antenna specifications

Feeder cable

7/8” Main feeder

Antenna specifications

Jumper cable 1/2” （JUMPER CABLE）

Antenna specifications

Connector 7/16”DIN-F（DIN CONNECTOR） 7/16”DIN-M（DIN & N CONNECTOR）

Antenna specifications

Lightning arrestor Rf port 2

Grounding

Antenna specifications

Accessories



Trimming Tool or Hand Tool Kit



Clamp



Earthing Kit



Wall Glands



Hoisting Stocking



Universal Ground Bar

Antenna specifications

Antenna system Antenna

7/16 Din Connector

1/2 Clamp

1/2 Jumper Tower Top Amplifier

7/8“ Cable

7/8“ Cable Grounding Machine house 1/2“ Jumper EMP

Grounding clip

Grounding bar Cabinet

Content Antenna overview Antenna specifications Principle of antenna selection

Principle of antenna selection

Radio propagation in cities 

Environment features:  Densely deployed BTS，small coverage area  Decrease over coverage and interference, increase frequency

reuse factor

Principle of antenna selection

Antenna selection in cities

Polarization Direction

Dual-polarization (Installation space) Directional antenna (Frequency reuse factor)

3dB bandwidth

60~65°(Control coverage)

Gain

15-16dBi

Tilt down angle

Fixed electrical tilt down

Principle of antenna selection

Radio propagation in suburb/rural area 

Environment features:  Loosely deployed BTS  light traffic  large coverage

Principle of antenna selection

Antenna selection in suburb/rural area

Polarization

Both dual-polarized and vertical directional

Direction

3dB bandwidth

90°105° 16-18dBi directional

Gain or 9－11dBi omni Mechanical tilt down; 50m high; null fill Tilt down angle

Principle of antenna selection

Radio propagation in road/highway environment



Environment features:  Low traffic  Fast moving subscribers

 Focus on coverage.  Strip coverage  Two sectors

 Omni-cell when pass

towns or tourist site

Principle of antenna selection

Antenna selection for highway

Polarization Direction 3dB bandwidth

Both dual-polarized and vertical Narrow beamwidth directional

30°

18dBi－22dBi Gain Tilt down angle No tilt down

Principle of antenna selection

Radio propagation in mountainous environment 

Environment features:  Block by mountains  Big propagation loss  Difficult to cover

Principle of antenna selection

Antenna selection in mountainous area

Polarization

Both dual-polarized and vertical

Direction

Omni or directional

3dB bandwidth

Big 3db verticle bandwidth Omni (9-11dBi）

Gain Directional (15-18dBi）

Tilt down angle

Null fill & electrical tilt down

Antenna Development

Wide frequency band Multi-function

High integration

Page

+45/900 -45/900 C 900/1800

C 900/1800

+45/900 +45/1800 -45/900 -45/1800 Page

+45/1800 -45/1800

ONE ANTENNA FOR MULTIPLE BANDS

^ ^ ^ ^ ^ ^ ^ ^

870-960MHz and 1710-1880MHz Extended band option with 806-960MHz Dual slant ±45º polarisation 65º horizontal beamwidth Band independent Teletilt™ control 17dBi gain in both bands Diplexed or Non-Diplexed versions Mechanical downtilt mounting option