Mw Transmission Basics

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  • Topic: Electromagnetic radiation, Antenna, Radio
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Microwave Transmission Basics

Microwave Transmission Basics
Table of Contents

• MW Advantages • MW Frequency bands • MW Link elements • Antenna Radiation Pattern • MW Alarms

Microwave Transmission Basics
Features Advantages


Rapid Deployment – A microwave link can be installed in as little as one day No right-of-way issues – Radio spans all obstacles such as roads, railways, etc., avoiding any requirement to seek permissions that inevitably are costly and introduce time delays. Flexibility – The capacity of a microwave link can be easily increased at minimal or even no cost. Radios can also be redeployed if network needs change or as a result of customer churn. Losing customers does not mean assets are lost like in the case of fiber build.





Microwave Transmission Basics
Features Advantages

• • •

Easily crosses city terrain – In many metropolitan and city authorities, street digging to install fiber is either extremely restricted, prohibitively expensive or is even banned outright. Operator-owned infrastructure - no reliance on competitors. Low start-up capital costs, which are independent of the link distance. Minimal recurring operational costs.




Radio infrastructure already exists for many networks in the form of rooftops, cellular masts and existing radio transmission towers. Microwave radio is not susceptible to common catastrophic failure of cable systems caused by cable cuts, and can be repaired in minutes instead of hours or days.

• Limitations
• • • Transmission Capacity Limits (i.e. PDH, STM-1) Competitive Transmission Media Optical Fiber (i.e. STM-1 up to STM-N)

Microwave Transmission Basics
Common M/W Frequency Bands
According to ITU-R recommendations

        

7 GHz 8 GHz 11 GHz 13 GHz 15 GHz 18 GHz 23 GHz 28 GHz 38 GHz

Note: Hop distance is depending on frequency. High frequency coincides with shorter transmission hop distance. Systems on 23 - 38 GHz are prone to rain attenuation.

Microwave Transmission Basics
M/W Channel Arrangement

Lower Band

F0

Upper Band

F1

F2

F3

F4

F5

F6 F1’

F2’

F3’

F4’

F5’

F6’

RF channel arrangement acc. ITU-R

Microwave Transmission Basics
Table of Contents

M/W Link Elements
 


   

IDU ODU Antenna— Functions Specifications Types Pressurization Equipments

Microwave Transmission Basics
Elements of a MW link
Antenna
ODU Free Space

Antenna
ODU

IDU
IF Cable IF Cable

IDU

Microwave Transmission Basics
Spur Link (Low Capacity Link)
7 - 38GHz Systems, generally used for PDH Spur Links Outdoor Unit (ODU, consists of RF-transmitter and antenna) IF-interconnection cable

Indoor Unit (IDU)

 




IDU Functions: Multiplexing /Demulteplexing of Tributaries. Modulation/Demodulation with the Carrier. IF conversion.

Microwave Transmission Basics
IDU BLOCK DIAGRAM:

Power Supply

155Mbps

Main Channel MUX/ DEMUX

Modulator
IF Card Cable Combi-ner

2 Mbps Wayside Channel

64 Kbps

User Channel

Demodulator

Coax Cable

NMS/Ethernet

External Alarms

IDU Controller

Microwave Transmission Basics
• ODU BLOCK DIAGRAM: Power Supply
AGC Voltage Reading
350MHz

TX Converter

3-4GHz

Coax Cable

AGC Cable Combiner

X Band Synthesizer RX Converter

Trans receiver Converter Amplifier

140 MHz

3-4GHz

IDU Controller

Microwave Transmission Basics

• •

Antenna Functions: Works as an amplifier to overcome the fade margin and give desired AGC levels. Antennas: Wire carrying HF Current is surrounded by Electric and Magnetic Fields Voltage Standing Wave radiation

2

Microwave Transmission Basics


Antennas: Voltage Standing Wave

radiation

Microwave Transmission Main Specification Basics
Antenna Radiation Pattern

Omni Antenna Lobe Point-to-Multipoint

Directional Antenna Lobe Point-to-Point

Microwave Transmission Basics
Antenna Gain:

Directive...
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