This document provides an overview of microwave link fundamentals, including:
1. Microwaves are electromagnetic radiations between 1-30 GHz used in telecommunications. Higher frequencies allow for higher bandwidth but require more advanced processing capabilities.
2. Microwave links are used in telecom industry applications like BTS connectivity and point of interconnect connectivity. Frequency allocation depends on distance, with shorter distances using higher frequencies.
3. Key factors that affect microwave links include reflection, refraction, diffraction, scattering, and absorption in the atmosphere. Diversity techniques like frequency and space diversity can help overcome some of these factors.
Microwave technology provides wireless transmission over medium distances using the microwave spectrum. It has advantages over wired systems in areas where cabling is not feasible. Microwaves propagate through free space and can be reflected, refracted, diffracted or scattered. Fading occurs due to multipath reflections and refractions. Fresnel zones must be clear for line of sight transmission. Technologies like space and frequency diversity and adaptive coding and modulation help mitigate fading. Microwave hardware consists of indoor and outdoor units connected by cables. Configurations include split mount, trunk mount and all outdoor. E-band millimeter wave uses higher frequencies for multi-gigabit links over short distances.
This document provides an overview of microwave communication. It discusses various topics related to microwave communication including possible media, manufacturers, advantages of microwave, characteristics, types of links and systems. It also covers topics such as line of sight requirements, wave propagation, multipath propagation, path loss, antenna types and gains. The document discusses concepts like fade margin, reliability and signal to noise ratio which are important in microwave system design. It provides examples of calculating free space loss and fresnel zone radius.
This document discusses point to point microwave transmission. It describes the basic modules of microwave radio terminals including digital modems, RF units, and passive parabolic antennas. It also covers microwave radio configurations, applications, advantages, planning aspects like network architecture, frequency bands, and propagation effects. Key factors in microwave link engineering like link budgets, reliability predictions, and interference analysis are summarized.
This document discusses the fundamentals of microwave link design. It covers topics such as the frequency ranges used, types of microwave links based on distance (long haul, medium haul, short haul), components of a microwave link including indoor and outdoor units, antennas, and factors that affect microwave link performance such as multipath fading and rain attenuation. It also provides information on polarization, diversity techniques, link budget calculations, and considerations for deploying microwave links.
The document discusses microwave radio communication systems. It covers topics like frequency bands used, line-of-sight requirements, Fresnel zone clearance, link budget calculations, fading effects and frequency planning. Key aspects include the need for clear line-of-sight between antennas, calculating fade margin to account for signal losses, and assigning frequencies to prevent interference while meeting quality objectives.
Microwaves are electromagnetic waves with wavelengths between 1-300 GHz, or 30-0.1 centimeters. A link budget accounts for all gains and losses in a telecommunication system from transmitter to receiver. It considers the effective radiated power from the transmitter plus antenna gain, and then subtracts losses like propagation through the medium and various other factors. The received power can be calculated using the effective isotropic radiated power minus total losses, which includes factors like free space loss, feeder loss, atmospheric absorption, and polarization mismatch.
This document provides an overview of GSM link budget calculations. It defines key terms used in link budgets such as effective radiated power, antenna gain, diversity gain, receiver sensitivity, path loss, and fade margin. It explains the objectives of calculating a link budget are to estimate maximum allowable path loss, compute required effective isotropically radiated power for a balanced link, estimate coverage design thresholds, and evaluate technology performance. It also provides examples of uplink and downlink link budget calculations for a GSM network and defines indoor, in-car, and outdoor coverage requirements.
An antenna converts radio frequency electric current into electromagnetic waves that are radiated into space. The same antenna can transmit and receive signals. Key antenna concepts include reciprocity, radiation patterns, gain, and polarization. Antenna gain compares its power output to an isotropic antenna. Common antennas include dipole, parabolic reflective, and types are optimized for propagation modes like ground wave, sky wave, and line-of-sight. Signal strength is reduced by factors like free space loss, noise, multipath, and fading over the transmission path.
Microwave technology provides wireless transmission over medium distances using the microwave spectrum. It has advantages over wired systems in areas where cabling is not feasible. Microwaves propagate through free space and can be reflected, refracted, diffracted or scattered. Fading occurs due to multipath reflections and refractions. Fresnel zones must be clear for line of sight transmission. Technologies like space and frequency diversity and adaptive coding and modulation help mitigate fading. Microwave hardware consists of indoor and outdoor units connected by cables. Configurations include split mount, trunk mount and all outdoor. E-band millimeter wave uses higher frequencies for multi-gigabit links over short distances.
This document provides an overview of microwave communication. It discusses various topics related to microwave communication including possible media, manufacturers, advantages of microwave, characteristics, types of links and systems. It also covers topics such as line of sight requirements, wave propagation, multipath propagation, path loss, antenna types and gains. The document discusses concepts like fade margin, reliability and signal to noise ratio which are important in microwave system design. It provides examples of calculating free space loss and fresnel zone radius.
This document discusses point to point microwave transmission. It describes the basic modules of microwave radio terminals including digital modems, RF units, and passive parabolic antennas. It also covers microwave radio configurations, applications, advantages, planning aspects like network architecture, frequency bands, and propagation effects. Key factors in microwave link engineering like link budgets, reliability predictions, and interference analysis are summarized.
This document discusses the fundamentals of microwave link design. It covers topics such as the frequency ranges used, types of microwave links based on distance (long haul, medium haul, short haul), components of a microwave link including indoor and outdoor units, antennas, and factors that affect microwave link performance such as multipath fading and rain attenuation. It also provides information on polarization, diversity techniques, link budget calculations, and considerations for deploying microwave links.
The document discusses microwave radio communication systems. It covers topics like frequency bands used, line-of-sight requirements, Fresnel zone clearance, link budget calculations, fading effects and frequency planning. Key aspects include the need for clear line-of-sight between antennas, calculating fade margin to account for signal losses, and assigning frequencies to prevent interference while meeting quality objectives.
Microwaves are electromagnetic waves with wavelengths between 1-300 GHz, or 30-0.1 centimeters. A link budget accounts for all gains and losses in a telecommunication system from transmitter to receiver. It considers the effective radiated power from the transmitter plus antenna gain, and then subtracts losses like propagation through the medium and various other factors. The received power can be calculated using the effective isotropic radiated power minus total losses, which includes factors like free space loss, feeder loss, atmospheric absorption, and polarization mismatch.
This document provides an overview of GSM link budget calculations. It defines key terms used in link budgets such as effective radiated power, antenna gain, diversity gain, receiver sensitivity, path loss, and fade margin. It explains the objectives of calculating a link budget are to estimate maximum allowable path loss, compute required effective isotropically radiated power for a balanced link, estimate coverage design thresholds, and evaluate technology performance. It also provides examples of uplink and downlink link budget calculations for a GSM network and defines indoor, in-car, and outdoor coverage requirements.
An antenna converts radio frequency electric current into electromagnetic waves that are radiated into space. The same antenna can transmit and receive signals. Key antenna concepts include reciprocity, radiation patterns, gain, and polarization. Antenna gain compares its power output to an isotropic antenna. Common antennas include dipole, parabolic reflective, and types are optimized for propagation modes like ground wave, sky wave, and line-of-sight. Signal strength is reduced by factors like free space loss, noise, multipath, and fading over the transmission path.
This document outlines an RF fundamentals course taught in 3 modules. Module 1 covers basics of RF including frequency, amplitude, wavelength, phase, and polarization. It also discusses transmission line fundamentals. Module 2 discusses RF communication systems, modulation techniques, and RF design. Module 3 covers wireless technologies like Bluetooth, WiFi, and cellular standards. The course provides assignments on topics like wavelength calculation and transmission line speed calculation in different materials. It also explains dBm calculations and concepts like signal to noise ratio, gain and loss.
1) The document provides an introduction to microwave radio communication fundamentals and IP applications. It discusses topics such as microwave spectrum, terrestrial microwave links and applications, microwave range, how microwave radios communicate, and extenders range with repeaters.
2) It then covers Layer 2 radio technology, the importance of propagation analysis, antennas and feeder systems, and RF protection. Diagrams and examples are provided to illustrate key concepts.
3) The goal is to provide network engineers an understanding of microwave fundamentals needed to design carrier Ethernet and IP microwave networks that transport voice, data, and online media with requirements for quality of service and reliability.
Microwave radio networks have several advantages over other network technologies including rapid deployment, flexibility, and lower costs. Common network architectures include spur, star, ring, and mesh configurations. Microwave propagation is affected by factors such as refraction, reflection, fading, and the environment. Careful network planning includes considerations for line of sight analysis, frequency selection, link engineering, and reliability predictions to ensure quality of service.
This document provides training materials on calculating wireless link budgets to determine the feasibility and optimal configuration of radio links. It defines key concepts like free space loss, link budget, antenna gain and Fresnel zone. An example link budget calculation is shown for a 5km link. It also introduces the Radio Mobile software tool, which can automatically simulate radio links and calculate the required Fresnel zone clearance by considering terrain profiles. The document concludes with an example of using Radio Mobile to analyze a potential link in Chuuk and poses questions about configuring the masts, transmit power and antennas.
The document discusses different types of antennas and their properties. It describes how antennas convert radio frequency energy into electromagnetic waves and how their physical size relates to wavelength. It then summarizes the main types of antennas including directional antennas like Yagi, panel and parabolic, and omni-directional antennas. It provides examples of common antenna radiation patterns and discusses concepts like polarization, reflector optics, aperture efficiency, and Cassegrain feeds.
This document provides an overview of microwave fundamentals including radio wave propagation characteristics, polarization, frequency bands, and key terminology. Radio waves propagate through mechanisms including reflection, refraction, scattering, and absorption. Polarization can be horizontal, vertical, or circular. Microwave frequencies are divided into bands such as L, S, C, X, Ku, K, and Ka. Important concepts covered include azimuth, AMSL, dB, dBm, antenna gain, beamwidth, and AGC.
This document provides an overview of key concepts in radio frequency (RF) technology for wireless communication systems. It defines terms like dBm for measuring power, and modulation schemes like amplitude shift keying (ASK), frequency shift keying (FSK), and phase shift keying (PSK) for encoding digital signals onto radio carriers. The document also outlines considerations for selecting an appropriate low-power wireless solution, including radio spectrum and network types.
Microstrip antennas come in various types based on their feeding mechanism, patch shape, operating frequency, and bandwidth. The main types include microstrip patch antennas, microstrip dipole antennas, printed slot antennas, and microstrip traveling wave antennas. Printed slot antennas comprise a slot in the ground plane of a grounded substrate and can take any shape. They are typically bidirectional radiators but can be made unidirectional using a reflected plate. Microstrip dipole antennas simply consist of two lengths of metal arranged end to end with feed in the middle. Microstrip traveling wave antennas support transverse wave propagation along periodic microstrip lines or long segments.
1. Microwaves are electromagnetic waves with frequencies between 500 MHz and 300 GHz, and wavelengths between 1 cm and 60 cm. They are used for applications like communications, radar, and heating.
2. There are several parameters used to analyze microwave systems including free space path loss, antenna gain, fade margin, and system reliability. Factors like frequency, path length, antenna size, and terrain affect these parameters.
3. Microwave systems have advantages like not requiring rights-of-way between stations and ability to carry large quantities of information due to short wavelengths. Challenges include difficulty in circuit design and implementation at microwave frequencies.
This document discusses various topics related to antennas and propagation, including:
- The basic functions of antennas for transmission and reception of signals
- Types of radiation and reception patterns that characterize antenna performance
- Common types of antennas like dipole, vertical, and parabolic reflective antennas
- Factors that influence signal propagation over distance like free space loss, noise, multipath interference, and atmospheric effects
- Techniques to improve reliability like diversity combining, adaptive equalization, and forward error correction coding.
The document discusses various topics related to radio wave propagation. It covers the different types of propagation including ground wave, space wave, and sky wave. It describes line of sight propagation and how increasing antenna height allows communication over longer distances. Tropospheric propagation is discussed along with how turbulence in the troposphere can scatter radio waves. The document also covers polarization of radio waves for different propagation types and the advantages of horizontal and vertical polarization. Finally, it defines attenuation and provides examples of attenuation levels through common materials.
The document provides information on wave propagation including:
1) It discusses Maxwell's equations and how electric and magnetic fields relate to wave propagation.
2) It describes different modes of propagation including ground waves, space waves, and sky waves. Sky waves involve reflection between the ionosphere and ground to allow long distance transmission.
3) Factors like solar activity and sunspots impact the ionosphere and affect the highest usable frequency for sky wave propagation at different times.
This document provides information about designing a microwave link between two sites in Pakistan for a semester project. It includes:
1) Details of the two sites and student information.
2) An introduction explaining microwave radio relay technology and how it is used to transmit signals over long distances using line-of-sight paths.
3) Technical explanations of key concepts in microwave communication systems like frequency, wavelength, free space loss, antenna gain, and how they relate to designing an optimal microwave link.
The document discusses parameters for planning and designing line-of-sight microwave communication links, including path loss calculations. It covers topics like survey requirements, link budget calculations, transmission concepts, tower heights, earth bulge, fresnel zones, frequency assignments and limitations of line-of-sight systems. Key aspects addressed include determining tower heights to clear obstructions along the signal path based on factors like frequency, distance, earth curvature and fresnel zone radius.
The document discusses small-scale fading and multipath propagation in wireless communications. It describes how multipath propagation leads to fading effects as multiple versions of the transmitted signal combine at the receiver. Channel sounding techniques are used to measure the power delay profile and characterize the time dispersion parameters of mobile radio channels, including mean excess delay, RMS delay spread, and maximum excess delay. Direct pulse systems, spread spectrum correlators, and frequency domain analysis are channel sounding methods discussed.
This document discusses wireless communication and radio wave propagation. It covers various types of fading that can occur for wireless signals, including small-scale and large-scale fading. Small-scale fading is caused by multipath propagation and can be frequency selective, flat, fast or slow depending on factors like bandwidth and receiver/transmitter motion. Doppler shift from movement introduces a change in frequency. Mitigation techniques for multipath fading include diversity methods using space, frequency or time as well as adaptive equalization and forward error correction.
The document discusses different types of microwave antennas and feeders for parabolic antennas. It describes horn antennas, parabolic antennas, slot antennas, dipole antennas, dielectric antennas, printed antennas, and phase array antennas. It also covers Gregorian, Cassegrain, horn, and omnidirectional feeders for parabolic antennas. Key details include how the different antenna types operate and their applications in areas like radar, wireless communication, and radio astronomy.
This document discusses Friis transmission formula for free space path loss. It defines key terms like power density, effective aperture, and antenna gain. The Friis formula calculates received power as a function of transmitted power, transmitter and receiver gains, wavelength, and distance. It states that path loss increases with distance and is inversely proportional to the square of the distance. The document also notes some drawbacks of the Friis model and conditions for applying it in the far field region.
Waveguides are hollow conductive tubes that propagate electromagnetic waves within their interior. They serve as boundaries that confine EM energy through reflection off their walls. Common waveguide types include rectangular, circular, and helical waveguides. Key characteristics of waveguides include their cutoff frequency minimum operating frequency and modes of propagation within the guide.
This document is a seminar report submitted by Rajan Meena to fulfill requirements for a Bachelor of Technology degree from Rajasthan Technical University. The report summarizes Rajan's 28-day training with Bharat Sanchar Nigam Limited (BSNL), India's state-owned telecommunications company. The report provides an overview of BSNL's role in India's telecommunications sector and describes key components of BSNL's basic telecommunications network, including call setup, electronic exchanges, carrier rooms, main distribution frames, and power plants. It also covers topics taught during the training like leased lines, intranets, corporate networks, Wi-Fi, WiMAX, and GSM.
This document summarizes the key considerations for designing a microwave link communication system, including site selection, equipment selection, tower selection, power equipment, lightning protection, and provides an example design between two sites. Site selection factors like terrain mapping, power/water access, and proximity to landmarks are outlined. Equipment specifications around antenna gain, receiver sensitivity, interface are described. Tower requirements involving load capacity, soil type, and height are also summarized.
This document outlines an RF fundamentals course taught in 3 modules. Module 1 covers basics of RF including frequency, amplitude, wavelength, phase, and polarization. It also discusses transmission line fundamentals. Module 2 discusses RF communication systems, modulation techniques, and RF design. Module 3 covers wireless technologies like Bluetooth, WiFi, and cellular standards. The course provides assignments on topics like wavelength calculation and transmission line speed calculation in different materials. It also explains dBm calculations and concepts like signal to noise ratio, gain and loss.
1) The document provides an introduction to microwave radio communication fundamentals and IP applications. It discusses topics such as microwave spectrum, terrestrial microwave links and applications, microwave range, how microwave radios communicate, and extenders range with repeaters.
2) It then covers Layer 2 radio technology, the importance of propagation analysis, antennas and feeder systems, and RF protection. Diagrams and examples are provided to illustrate key concepts.
3) The goal is to provide network engineers an understanding of microwave fundamentals needed to design carrier Ethernet and IP microwave networks that transport voice, data, and online media with requirements for quality of service and reliability.
Microwave radio networks have several advantages over other network technologies including rapid deployment, flexibility, and lower costs. Common network architectures include spur, star, ring, and mesh configurations. Microwave propagation is affected by factors such as refraction, reflection, fading, and the environment. Careful network planning includes considerations for line of sight analysis, frequency selection, link engineering, and reliability predictions to ensure quality of service.
This document provides training materials on calculating wireless link budgets to determine the feasibility and optimal configuration of radio links. It defines key concepts like free space loss, link budget, antenna gain and Fresnel zone. An example link budget calculation is shown for a 5km link. It also introduces the Radio Mobile software tool, which can automatically simulate radio links and calculate the required Fresnel zone clearance by considering terrain profiles. The document concludes with an example of using Radio Mobile to analyze a potential link in Chuuk and poses questions about configuring the masts, transmit power and antennas.
The document discusses different types of antennas and their properties. It describes how antennas convert radio frequency energy into electromagnetic waves and how their physical size relates to wavelength. It then summarizes the main types of antennas including directional antennas like Yagi, panel and parabolic, and omni-directional antennas. It provides examples of common antenna radiation patterns and discusses concepts like polarization, reflector optics, aperture efficiency, and Cassegrain feeds.
This document provides an overview of microwave fundamentals including radio wave propagation characteristics, polarization, frequency bands, and key terminology. Radio waves propagate through mechanisms including reflection, refraction, scattering, and absorption. Polarization can be horizontal, vertical, or circular. Microwave frequencies are divided into bands such as L, S, C, X, Ku, K, and Ka. Important concepts covered include azimuth, AMSL, dB, dBm, antenna gain, beamwidth, and AGC.
This document provides an overview of key concepts in radio frequency (RF) technology for wireless communication systems. It defines terms like dBm for measuring power, and modulation schemes like amplitude shift keying (ASK), frequency shift keying (FSK), and phase shift keying (PSK) for encoding digital signals onto radio carriers. The document also outlines considerations for selecting an appropriate low-power wireless solution, including radio spectrum and network types.
Microstrip antennas come in various types based on their feeding mechanism, patch shape, operating frequency, and bandwidth. The main types include microstrip patch antennas, microstrip dipole antennas, printed slot antennas, and microstrip traveling wave antennas. Printed slot antennas comprise a slot in the ground plane of a grounded substrate and can take any shape. They are typically bidirectional radiators but can be made unidirectional using a reflected plate. Microstrip dipole antennas simply consist of two lengths of metal arranged end to end with feed in the middle. Microstrip traveling wave antennas support transverse wave propagation along periodic microstrip lines or long segments.
1. Microwaves are electromagnetic waves with frequencies between 500 MHz and 300 GHz, and wavelengths between 1 cm and 60 cm. They are used for applications like communications, radar, and heating.
2. There are several parameters used to analyze microwave systems including free space path loss, antenna gain, fade margin, and system reliability. Factors like frequency, path length, antenna size, and terrain affect these parameters.
3. Microwave systems have advantages like not requiring rights-of-way between stations and ability to carry large quantities of information due to short wavelengths. Challenges include difficulty in circuit design and implementation at microwave frequencies.
This document discusses various topics related to antennas and propagation, including:
- The basic functions of antennas for transmission and reception of signals
- Types of radiation and reception patterns that characterize antenna performance
- Common types of antennas like dipole, vertical, and parabolic reflective antennas
- Factors that influence signal propagation over distance like free space loss, noise, multipath interference, and atmospheric effects
- Techniques to improve reliability like diversity combining, adaptive equalization, and forward error correction coding.
The document discusses various topics related to radio wave propagation. It covers the different types of propagation including ground wave, space wave, and sky wave. It describes line of sight propagation and how increasing antenna height allows communication over longer distances. Tropospheric propagation is discussed along with how turbulence in the troposphere can scatter radio waves. The document also covers polarization of radio waves for different propagation types and the advantages of horizontal and vertical polarization. Finally, it defines attenuation and provides examples of attenuation levels through common materials.
The document provides information on wave propagation including:
1) It discusses Maxwell's equations and how electric and magnetic fields relate to wave propagation.
2) It describes different modes of propagation including ground waves, space waves, and sky waves. Sky waves involve reflection between the ionosphere and ground to allow long distance transmission.
3) Factors like solar activity and sunspots impact the ionosphere and affect the highest usable frequency for sky wave propagation at different times.
This document provides information about designing a microwave link between two sites in Pakistan for a semester project. It includes:
1) Details of the two sites and student information.
2) An introduction explaining microwave radio relay technology and how it is used to transmit signals over long distances using line-of-sight paths.
3) Technical explanations of key concepts in microwave communication systems like frequency, wavelength, free space loss, antenna gain, and how they relate to designing an optimal microwave link.
The document discusses parameters for planning and designing line-of-sight microwave communication links, including path loss calculations. It covers topics like survey requirements, link budget calculations, transmission concepts, tower heights, earth bulge, fresnel zones, frequency assignments and limitations of line-of-sight systems. Key aspects addressed include determining tower heights to clear obstructions along the signal path based on factors like frequency, distance, earth curvature and fresnel zone radius.
The document discusses small-scale fading and multipath propagation in wireless communications. It describes how multipath propagation leads to fading effects as multiple versions of the transmitted signal combine at the receiver. Channel sounding techniques are used to measure the power delay profile and characterize the time dispersion parameters of mobile radio channels, including mean excess delay, RMS delay spread, and maximum excess delay. Direct pulse systems, spread spectrum correlators, and frequency domain analysis are channel sounding methods discussed.
This document discusses wireless communication and radio wave propagation. It covers various types of fading that can occur for wireless signals, including small-scale and large-scale fading. Small-scale fading is caused by multipath propagation and can be frequency selective, flat, fast or slow depending on factors like bandwidth and receiver/transmitter motion. Doppler shift from movement introduces a change in frequency. Mitigation techniques for multipath fading include diversity methods using space, frequency or time as well as adaptive equalization and forward error correction.
The document discusses different types of microwave antennas and feeders for parabolic antennas. It describes horn antennas, parabolic antennas, slot antennas, dipole antennas, dielectric antennas, printed antennas, and phase array antennas. It also covers Gregorian, Cassegrain, horn, and omnidirectional feeders for parabolic antennas. Key details include how the different antenna types operate and their applications in areas like radar, wireless communication, and radio astronomy.
This document discusses Friis transmission formula for free space path loss. It defines key terms like power density, effective aperture, and antenna gain. The Friis formula calculates received power as a function of transmitted power, transmitter and receiver gains, wavelength, and distance. It states that path loss increases with distance and is inversely proportional to the square of the distance. The document also notes some drawbacks of the Friis model and conditions for applying it in the far field region.
Waveguides are hollow conductive tubes that propagate electromagnetic waves within their interior. They serve as boundaries that confine EM energy through reflection off their walls. Common waveguide types include rectangular, circular, and helical waveguides. Key characteristics of waveguides include their cutoff frequency minimum operating frequency and modes of propagation within the guide.
This document is a seminar report submitted by Rajan Meena to fulfill requirements for a Bachelor of Technology degree from Rajasthan Technical University. The report summarizes Rajan's 28-day training with Bharat Sanchar Nigam Limited (BSNL), India's state-owned telecommunications company. The report provides an overview of BSNL's role in India's telecommunications sector and describes key components of BSNL's basic telecommunications network, including call setup, electronic exchanges, carrier rooms, main distribution frames, and power plants. It also covers topics taught during the training like leased lines, intranets, corporate networks, Wi-Fi, WiMAX, and GSM.
This document summarizes the key considerations for designing a microwave link communication system, including site selection, equipment selection, tower selection, power equipment, lightning protection, and provides an example design between two sites. Site selection factors like terrain mapping, power/water access, and proximity to landmarks are outlined. Equipment specifications around antenna gain, receiver sensitivity, interface are described. Tower requirements involving load capacity, soil type, and height are also summarized.
This document discusses the design of terrestrial microwave links. It begins with an introduction to microwave links and their basic components - transmitters, towers, antennas, and receivers. Antennas must have line-of-sight between sites. The document then covers topics like frequency standards, polarization, antenna types, link budgets, and operating frequencies. It provides block diagrams of transmitter and receiver base stations. Key components like mixers, filters, amplifiers and their functions are described. Signal spreading in W-CDMA systems is also explained. Technical characteristics of microwave point-to-point links are outlined.
The document discusses key concepts in digital telecommunication networks including Pulse Code Modulation (PCM), Plesiochronous Digital Hierarchy (PDH), Synchronous Digital Hierarchy (SDH), and their frame structures and bit rates. It describes how lower bit rate signals such as E1 (2Mbps) are mapped into higher bit rate structures like STM-1 (155.52Mbps) through multiplexing techniques involving containers, virtual containers, tributary units, and administrative units. The document also outlines the section overhead bytes used in SDH for functions like frame alignment, error monitoring, and automatic protection switching.
The document discusses different components of MINI-LINK microwave networks, including point-to-point systems, point-to-multipoint systems, and network management. It describes the MINI-LINK High Capacity, MINI-LINK E Classic, MINI-LINK E Traffic Node, and MINI-LINK BAS systems for point-to-point and point-to-multipoint connections. It also discusses the MINI-LINK Manager for centralized network supervision, operation, and maintenance across multiple sub-networks and operator workplaces.
The document discusses using different media to culture cells and measure yellow fluorescence over time. SC medium normally contains yellow fluorescent components. Cells were cultured in VD medium without riboflavin and their yellow fluorescence, peaking at 524nm, increased over time when excited at 430nm. The fluorescent material could pass through a dialysis membrane. A 3D fluorescent spectrum of the cell culture supernatant showed peaks from the excitation light. Using excitation between 500-525nm could avoid measuring yellow fluorescence from the supernatant.
TNS is an Indian telecom solutions provider offering infrastructure services, manufacturing, training and software. It has divisions for towers, shelters, ECOS, network and training. The document provides an overview of TNS' vision, organizational structure, financial growth, quality processes, project experience, manufacturing facilities and network services.
This document provides information about microwave technology including:
1) Microwave frequencies range from 300MHz to 300GHz but communication uses 3GHz to 30GHz. Microwaves propagate as plane waves with electric and magnetic fields perpendicular to the direction of travel.
2) Common microwave link frequencies are listed between 2GHz and 38GHz. Microwave links can carry PDH, SDH, Ethernet and combinations of these protocols.
3) Microwave propagation is affected by the atmosphere through refraction, reflection, absorption and diffusion. The ground also impacts propagation through diffraction and reflection. Diversity techniques like space, frequency and polarization can overcome signal losses.
The document discusses Plesiochronous Digital Hierarchy (PDH) and Synchronous Digital Hierarchy (SDH) technologies. PDH uses bit interleaving to transmit multiple digital signals over fiber optic or microwave networks at nearly synchronized rates. SDH was developed as international standard to overcome limitations of PDH like inefficient bandwidth usage. SDH uses synchronous transmission and defines a hierarchical structure of containers, tributaries and frames to efficiently transport digital signals and switch traffic.
PDH and SDH are digital multiplexing techniques. PDH uses asynchronous multiplexing and operates over asynchronous networks, applying positive justification. It allows tributary clocks to differ slightly. SDH uses synchronous multiplexing and operates over synchronous networks, applying zero justification. Tributary clocks must be synchronized to a master clock. SDH was developed to simplify interconnection between network operators and expand compatibility by establishing a international standard to replace the different PDH standards.
- Polymer molecular weight determines many physical properties like transition temperatures and mechanical properties.
- Molecular weight distributions are described using average values like number average (MN), weight average (MW), and viscosity average (MV).
- For condensation polymers formed from bifunctional monomers, the most probable molecular weight distribution was derived by Flory. It results in a monotonically decreasing function with the monomer being the most probable species even at high conversion.
Microwave technology can be used for LANs, extended LANs, and mobile computing. It uses either terrestrial (ground-based) links or satellite links. There are three forms of mobile computing: packet-radio networking, cellular networking, and satellite station networking. Terrestrial microwave links employ line-of-sight transmitters and receivers in the low gigahertz range, requiring stations every 30 miles, while satellite links use geosynchronous satellites to relay signals over long distances. Microwave systems offer advantages like no cables and wide bandwidth but have disadvantages like disruption from obstacles and signal absorption.
This document provides an overview of Synchronous Digital Hierarchy (SDH) including its introduction, components, frame structure, and applications. SDH was developed to provide a standardized digital transmission network with vendor independence. It uses optical fiber to enable end-to-end monitoring and self-healing ring architectures for survivability. The SDH frame structure consists of sections for transport overhead (TOH), path overhead (POH), and payloads. SDH supports multiplexing of various signals like E1, DS1, and STM streams. It allows dynamic bandwidth allocation and is a platform for future services.
This document discusses troubleshooting of OptiX RTN 600 equipment. It covers objectives of troubleshooting preparation, ideas and methods, and examples of classified troubleshooting situations. Common troubleshooting methods discussed include alarm and performance analysis, loopback, replacement, configuration data analysis, configuration modification, using testing instruments, and experience-based rules of thumb. Typical troubleshooting sequences are also presented, beginning with excluding external issues and locating faults to a single network element or board. Finally, examples of traffic interruptions, wrong configurations, and bit errors are analyzed.
Microwave antennas can take several forms. Horn antennas are popular and can achieve gains up to 25 dB, with directional patterns. Parabolic antennas, like satellite dishes, typically have very high gain between 30-40 dB and low cross polarization. Slot antennas are often used instead of line antennas for greater pattern control and are found in radar and cell antennas. Dipole antennas are half wave resonant conductors that radiate omnidirectionally at right angles to their axis. Their gain is approximately 2 dBi. Dielectric antennas use a traveling surface wave along a dielectric rod to radiate maximally along the rod axis.
This document provides an overview of digital microwave communication principles and concepts. It begins with an introduction explaining that the course is intended to educate engineers on the basics of digital microwave communications. It then outlines the learning objectives, which include explaining the concepts, components, networking modes, propagation principles, anti-fading technologies, and design of microwave transmission links. The document also includes sections on the history and development of microwave communication, definitions of key terms, modulation techniques, frame structures, equipment types, and antenna technology.
In this paper, we discussed about LTE system throughput calculation for both TDD and FDD system.
3GPP LTE technology support both TDD and FDD multiplexing. The paper describes all the factors which affect the throughput like Bandwidth, Modulation, UE category and mulplexing. It also describes how we get throughput 300Mbps in DL and 75Mbps in UL and what are assumptions taken to calculate the same.
Paper describes the steps and formulae to calculate the throughput for FDD system for TDD Config 1 and Config 2.
The throughput calculations shown in this paper is theoretical and limited by the assumptions taken to calculate for calculations
This document describes a proposed system for wirelessly charging mobile phones using microwaves transmitted from cell towers. It discusses the relevant components including a magnetron transmitter, slotted waveguide antenna, rectenna receiver, and sensor circuitry. The system would allow phones to charge as users make calls by converting received microwave energy to DC electricity via rectification. While avoiding wired charging, potential disadvantages include radiation risks, dependence on network coverage, and slow charging rates. The overall goal is to enable mobile charging anywhere without requiring charging facilities.
This document describes a proposed technology for wirelessly charging mobile phones using microwaves. It discusses how microwaves could be transmitted from base stations via a magnetron and slotted waveguide antenna. Mobile phones would be equipped with a rectenna to convert the microwave energy into electricity. The receiver section would use a sensor circuit and rectification process using a Schottky diode to produce DC power for charging. While this could allow for more convenient wireless charging over distances, concerns about radiation exposure and dependence on network coverage would need to be addressed. The technology could potentially transform mobile phone charging by eliminating wired connections.
Microstrip Antenna for ISM Band (2.4GHz) Applications-A reviewIJERA Editor
The past decade has seen a rapid development of wireless communication systems. This continuous trend is bringing about a wave of new wireless devices placing several demands on the antenna such as size miniaturization, power consumption, simplicity, compatibility with printed-circuit technology, low profile, light weight, lower return loss and good radiation properties. This paper provides a comprehensive review of the research work done in the recent past by various authors on the design and optimization of the planar microstrip antenna operating in ISM band. An exhaustive list of reference has been provided.
World cannot be imagined without electrical
power. Generally the power is transmitted through
transmission networks. This paper describes an original
idea to eradicate the hazardous usage of electrical wires
which involve lot of confusion in particularly organizing
them. Imagine a future in which wireless power transfer is
feasible: cell phones, household robots, mp3 players,
laptop computers and other portable electronic devices
capable of charging themselves without ever being plugged
in freeing us from that final ubiquitous power wire. This
paper includes the techniques of transmitting power
without using wires with an efficiency of about 95% with
non-radioactivemethods. In this paper wireless power
transfer technique have been implemented on test system.
Keywords : power, ubiquitous, efficiency
The document appears to be a laboratory journal for a student named Rishabh Gogna who completed a course in Microwave Engineering Lab. It includes a certificate of completion, index of 10 experiments conducted, and reports on each experiment. The experiments include studying microwave components, the RF behavior of resistors and other circuit elements, designing a rectangular cavity resonator, and measuring wavelength, frequency, power and VSWR using a microwave test bench. The overall goal appears to have been for the student to gain hands-on experience with common microwave devices and measurement techniques.
Multiband Microstrip Antenna for Wi-MAX Application-A studyIJERA Editor
The wireless revolution is transforming the existing global telecommunications networks into an integrated system providing a broad class of communication services to customers anywhere, anytime in motion or fixed. An antenna is an important device in wireless communication system as its performance will have direct effect on the total system. The continuous shrinking of size of the electronic systems demands small size of antenna elements which can cater the need of multiband operation in order to fit properly in wireless devices without compromising the radiation properties of the antenna. This paper presents a review of the research work done by various authors on the topic multiband microstrip antenna for Wi-MAX application in the recent past.
Circuits for Optical Based Line of Sight Voice CommunicationjournalBEEI
We present here line of sight communication between a person and his neighbour with the help of optical signal produced by a laser torch which act as a carrier. It is therefore a wireless communication and the transmission can go up to 500 meters. We used photodiode to receive the signal at the receiver. The transmitter circuit comprises condenser microphone transistor amplifier BC547 followed by an op-amp stage built around µA741. When we give a voice signal from the mike, it converts the voice signal into the electrical signal. This electrical signal is fed to IC741 (op-amp) for amplification. The gain of the op-amp can be controlled with the help of 1-mega-ohm potentiometer. The AF output from IC is coupled to the base of a class B amplifier which, in turn, modulates the signal. The transmitter uses 5V power supply. However, the 3-volt laser torch (after removal of its battery) can be directly connected to the circuit-with the body of the torch connected to the class B. The photodiode converts the optical signal into electrical signal and again this signal is amplified using IC741 and a combination of class B push pull amplifiers. The receiver circuit uses an NPN photodiode as the light sensor that is followed by a two-stage transistor preamplifier and IC741 based audio Power amplifier. The receiver does not need any complicated alignment. Just keep the photodiode oriented towards the remote transmitter’s laser point and adjust the volume control for a clear sound. The sensor must not directly face the sun.
Planar Inverted-F Antenna for GPS Application - A studyIJERA Editor
survey of recent studies and findings on wireless technology and its applications are explored aggressively in few areas that have the greatest potential for achieving entirely new capabilities using antennas. we have presented in depth conceptual understanding of antennas and potential application in wireless communication an exhaustive list of reference has been proceed.
The document discusses waveguides, which are hollow metallic tubes that transmit electromagnetic waves through successive reflections off the inner walls. There are two main types of waveguides: rectangular and circular. Rectangular waveguides support TE and TM modes of propagation, with the dominant TE10 mode determining the cutoff frequency below which waves do not propagate. Circular waveguides have advantages like greater power handling capacity but are larger in size. Common applications of waveguides include radar systems and long-distance high-frequency signal transmission.
Study of multiple antennas with defected ground slot for low-band LTE applica...journalBEEI
This study is focused on highly coupled multiple antennas with defected ground slot techniques. Two Printed Inverted-F Antenna (PIFA) are positioned at the top edge of chassis symmetrically. Both antennas are operating at low-band Long-Term Evolution (LTE) with center frequency, 829MHz. Rectangular defected ground slot is implemented to reduce the coupling effect between the antennas on the ground plane of the small chassis. Parameter study of the rectangular defected ground slot is studied with different width, W and length, L. Furthermore, the optimized dimensions of rectangular defected ground slot, W and L are simulated and presented. The optimized defected ground slot reduced the mutual coupling up to -4.5 dB. The envelope correlation coefficient (ECC) achieved less than 0.5. The ground plane of the multiple antenna structure has been further investigated by introducing another slot with a gap of 1mm between them. The achieved result is not significant in term of S-parameter and ECC compared to single defected ground slot.
This project report discusses wireless power transmission techniques. It begins by introducing wireless power transmission and some of its advantages over wired transmission. It then describes various near-field techniques like inductive coupling and resonant inductive coupling. Far-field techniques like microwave power transmission and laser power transmission are also summarized. Key differences between various techniques are highlighted. The report provides examples and diagrams to illustrate wireless power transmission concepts.
Directional couplers are widely used as passive and active optical devices in fibre and integrated optics, and form the basis of components such as switches, modulators and wavelength filters. They consist of two closely-spaced parallel waveguides, whose separation is sufficiently small that power may be transferred between the modes propagating in the two guides through an interaction involving their evanescent fields. In this paper results are presented for a range of near infrared single mode silica directional couplers fabricated by electron beam irradiation. The effects of over cladding layers will be highlighted. Changes on coupling coefficient due to different cladding refractive indexes will also be examined. The coupled mode theory will be employed to fit the experimental results with prediction by theory. It is found that over cladding layer alters the transmission characteristics of silica directional couplers.
This document discusses various propagation models used in wireless communications. It begins by introducing the free space propagation model and 2-ray ground reflection model. It then describes the key propagation mechanisms of reflection, diffraction, and scattering. Reflection from smooth surfaces and conductors is explained. Fresnel zone geometry and knife edge diffraction models are used to analyze diffraction. Buildings can help diffraction by providing some gain, with the amount of diffracted energy dependent on factors like height and frequency. Propagation effects must be considered for accurate wireless system design and performance prediction.
This document summarizes the design of a dual-band microstrip patch antenna that operates at 1.713 GHz and 2.93 GHz using reactive slot loading. Narrow slots are etched close to the radiating edges of the rectangular patch, forcing current to take a longer path and lowering the resonant frequency. Simulation results show return losses of -14.87 dB and -11.87 dB at the two operating frequencies, with radiation patterns normal to the patch surface and VSWR values below 1.7, indicating good impedance matching performance. The design approach demonstrates a single-layer single-feed dual-frequency antenna for applications requiring operation at multiple bands.
This document provides an overview of basic antenna principles and types used for mobile communications. It discusses the theory behind how antennas work and key definitions such as polarization, radiation pattern, gain and impedance. It also describes different types of antennas used for base stations, vehicles, portable devices and in GSM/DCS networks, including omnidirectional, directional, diversity and indoor antennas. Specific antenna technologies covered include groundplane, skirt, yagi, log-periodic, panel and corner reflector designs.
This document describes the design of a tunable antenna for cognitive radios operating in the UHF TV band (470-806 MHz). It discusses:
1) The design of a generalized impedance matching circuit using a π-network of fixed inductors and variable capacitors to match the antenna's impedance across the entire UHF TV band. The capacitors can be tuned digitally.
2) The use of a digitally tunable capacitor (DTC) in the impedance matching circuit to allow software control of the capacitance. Models of the DTC circuit elements and their variation with tuning state are presented.
3) A simplified equivalent circuit model of the DTC configured in shunt mode
Background/Objectives: The main aim of this research paper is to evaluate thedifferent linearly polarized
modes for two channel MDM passive optical network. Methods/Statistical Analysis: In this work mode division
multiplexing from 48 users. Three different combinations of linear polarized modes is tested for odd modes,
even modes and consecutive modes.System evaluated for 55 Km also on higher launched powers.Findings:
Results revealed that mode number 1,3 and 5 perform better and suffered from less mode crosstalk. However
even modes perform less effective than odd modes but better than mode number 1,2 and 3.Further 16 user for
each mode is splitted and 10 dB optimal power is found, beyond this power system performance degrated.LP 01
provide maximum quality factor and worst in case of LP 21 mode.
Strategies for Effective Upskilling is a presentation by Chinwendu Peace in a Your Skill Boost Masterclass organisation by the Excellence Foundation for South Sudan on 08th and 09th June 2024 from 1 PM to 3 PM on each day.
This presentation includes basic of PCOS their pathology and treatment and also Ayurveda correlation of PCOS and Ayurvedic line of treatment mentioned in classics.
Main Java[All of the Base Concepts}.docxadhitya5119
This is part 1 of my Java Learning Journey. This Contains Custom methods, classes, constructors, packages, multithreading , try- catch block, finally block and more.
This slide is special for master students (MIBS & MIFB) in UUM. Also useful for readers who are interested in the topic of contemporary Islamic banking.
How to Setup Warehouse & Location in Odoo 17 InventoryCeline George
In this slide, we'll explore how to set up warehouses and locations in Odoo 17 Inventory. This will help us manage our stock effectively, track inventory levels, and streamline warehouse operations.
How to Make a Field Mandatory in Odoo 17Celine George
In Odoo, making a field required can be done through both Python code and XML views. When you set the required attribute to True in Python code, it makes the field required across all views where it's used. Conversely, when you set the required attribute in XML views, it makes the field required only in the context of that particular view.
How to Fix the Import Error in the Odoo 17Celine George
An import error occurs when a program fails to import a module or library, disrupting its execution. In languages like Python, this issue arises when the specified module cannot be found or accessed, hindering the program's functionality. Resolving import errors is crucial for maintaining smooth software operation and uninterrupted development processes.
2. MICROWAVE LINK - FUNDAMENTALS
INTRODUCTION
Definition of Microwave
Microwaves are electromagnetic radiations in the frequency range 1 GHz to 30 GHz
(generally for Telecom).
Various books uses various frequency ranges for identifying microwaves. Radio Frequency
or Microwaves are two different terms used to break monotony. This means both terms
convey similar meaning. Frequency from 300 MHz to 300 GHz are used in various ranges to
define range of RF / Microwaves.
It is to be noted that higher the frequency, higher the bandwidth. Thus using high
frequency gives us facility of transferring more data. However, everything comes with a
price. High frequency means high processing capabilities are required and thus higher the
cost. But use of frequency spectrum is very high and thus latter (i.e. high cost for high
capabilities) is generally adapted now a days.
MICROWAVE APPLICATIONS FOR TELECOM INDUSTRY
1. BTS connectivity
2. STM 1 (63 E1) ring closure
3. BTS on spur
4. Point of Interconnect (POI) connectivity.
(If you are not familiar with above telecommunication terms, refer tutorial on "Introduction
to basic fundamentals in telecom industry")
3. FREQUENCY - MW LINKS
Frequency used in MW Links
Microwave links of short distances are generally allocated with higher frequencies, because high
frequency means high losses in air and thus it is good to have short distances in these
cases. While for distances like 20-35 Kms or so we use lower frequencies. Please note that the
terms high and low used for frequencies are relative and the values for these terms can be
15/18 GHz or 6/7 GHz say.
Microwave Links can be of two types
1. SDH
2. PDH
Frequency allocated to MW link does not depend on the type of MW link. If the type of MW
link is to be explained in easiest possible manner, it may be as follows.
SDH link can carry optical signals i.e. each BTS falling in this MW link will have to have transport
equipment to convert optical signal into electrical signal. This is good if we wish to have MW
links of large no of hops and wish to use it for ring closure. In this case only what is required will
be dropped without disturbing the whole link. SDH link can carry maximum of STM 1 i.e. 64 E1s
as a whole for one MW ring.
PDH link can carry electrical signals i.e. all 16E1s (capacity of PDH link) will have to be dropped in
site falling in this link. Remaining E1s can then be retransmitted for next hop. (Hop means single
MW link)
Continue..
4. SOME PARAMETERS
For 15 GHz link, Tx and Rx bandwidth is 28
MHz. Tx and Rx separation is 420 MHz. This
separation is defined by ITU and is there to
avoid interference.
For 6 GHz link Tx and Rx separation is 152 MHz.
For 7 GHz link Tx and Rx separation is 154 MHz.
5. PRACTICAL VIEW - MW LINKS
If we wish to look at practical implementation of MW links in telecom industry, we can start from
Fig MW.4.1
Fig MW.4.1 General MW Link Setup in Field
In Door Unit (IDU) which resides in Shelter, acts as Modem i.e. Modulator and Demodulator. It
takes electrical / optical signal and convert it into analog (electromagnetic) which is sent to ODU
(Out Door Unit).
IF cable is a co-axial cable which carries Intermediate Frequency. Details of IF cable can be seen
in Fig MW.4.2. You can feel free to ignore this figure and continue. Generally, maximum
permissible length of IF cable from IDU to ODU is 300m and frequency do not exceed 2 GHz.
Fig MW.4.2 IF Cable
6. Continue..
ODU is present just near MW antenna at height in tower. ODU performs upconversion (acts
as Mixer) to convert signal into required frequency allocated. For doing this ODU also have
high power amplifiers and filters. Since ODU output is high frequency cable connecting
ODU to antenna is "RF Low Loss Cable". Generally, for 6/7 GHz link this low loss cable is
used and for 15/18 GHz link waveguide is used to connect ODU to antenna.
7. POLARIZATION
Polarization defines the way of movement of MW waves in air. It can be either Linear or
Circular.
Type of Polarization
1. Linear - can be sub-divided into Vertical and Horizontal
2. Circular
VERTICAL POLARIZATION
An electromagnetic wave is said to be following Vertical Polarization if its electrical component is
perpendicular to the horizon of earth as shown in Fig MW.5.1
Fig MW.5.1 Vertical Polarization
8. HORIZONTAL POLARIZATION
An electromagnetic wave is said to be following Horizontal Polarization if its electrical
component is parallel to the horizon of earth as shown in Fig MW.5.2
Fig MW.5.2 Horizontal Polarization
CIRCULAR POLARIZATION
An electromagnetic wave is said to be following Circular Polarization if it radiates electric and
magnetic field in all directions i.e. they keep on rotating. Phase is the deciding factor
here. Don't worry about this... We generally do not use this in MW links.
9. WHICH POLARIZATION IS BETTER FOR MW LINKS?
There is no straight forward answer for this question. Definitely one can point out Vertical
Polarization as the best in first view because it is more prone to rain fading. Rain droplets are
generally flattened with increase in size (See Fig MW.5.3) and thus Vertical polarization is more
prone and less affected. However, horizontal polarization is very much used to avoid
interference, in case nearby areas are using Vertical Polarization. (See Fig MW.5.4)
So, vertical polarization is generally used for high frequency links, because high frequencies are
more prone to rain fading and horizontal polarization is generally used to avoid
interference. However, this cannot be treated as rule. Each operator is free to decide.
Fig MW.5.3 Rain Droplets Fig MW.5.4 Use of V and H Polarization to avoid interference
10. FACTORS AFFECTING MW LINK
Following major phenomenon affect MW Link
1. REFLECTION
2. REFRACTION
3. DIFFRACTION
4. SCATTERING
5. ABSORPTION
11. Factors affecting MW link - REFLECTION
REFLECTION
Reflection is one of the major factors that affect MW link. Fig MW.7.1 explains this
phenomenon.
Water is good reflector. Reflected Wave can have different phase and amplitude as compared
to LOS wave. Thus, this causes Fading of signal at receiver and this fading is called Multi Path
Fading.
To overcome this problem, we either adjust antenna heights at two ends to avoid major source
of reflection or to reduce its intensity. Another solution is to use Space Diversity, about which
we will study later in this tutorial.
NOTE:
Trees are good absorbers. So, if trees are present in between MW link, chances of reflection
reduces drastically.
Fig MW.7.1 Reflection in MW Link
12. Factors affecting MW link - REFRACTION
DO YOU KNOW THIS ?
Theory says that MW / electromagnetic waves travel in a straight line and yes, they do so in
vacuum. But when it comes to atmosphere, it may come as surprise to most of us that MW
waves do not travel in a straight line. Phenomenon responsible for this is REFRACTION. Density
in atmosphere is not uniform. It varies from one place to another. As we all know that light ray
bends towards or away from normal as it moves from higher density medium to lower or vice
versa, we can easily understand why MW waves deviate from straight line path in atmosphere.
In homogeneous atmosphere vertical change in dielectric constant is gradual and hence bending
or refraction is continuous. Ray is bent from thinner density air towards thicker making it follow
earth curvature. This can be related with radii of spheres. First radius is of earth (6370 Km
approx) and second is formed by curvature of beam of ray with its center coinciding center of
earth.
We can define K Factor using above information
K-Factor = R / R`
where
R = Radius of ray beam curvature
R` = Radius of earth
K=4/3 for earth's atmosphere.
Fig MW.8.1 shows value of K according to path traveled by MW wave.
Fig MW.8.1 K-Factor in MW Link
13. Factors affecting MW link - Diffraction, Scattering & Absorption
DIFFRACTION
Diffraction of wave occurs when bending takes place at sharp irregular edges. This diffracted
wave can interfere very much with desired signal.
SCATTERING
Scattering of ray of light occurs when object it strikes is of smaller size that its own wavelength.
ABSORPTION
Above 10 GHz, absorption in atmosphere becomes dominant. Rain droplets become
comparable to wavelength.
This absorption can be 2 dB/Km or can be as high as 3 dB/Km in case of rain.
14. DIVERSITY IN MW LINKS
Diversity in MW Links is a sort of redundancy in network. They also help overcome various
factors which affect MW links.
Two types of Diversity in MW links
1. Frequency Diversity
2. Space Diversity
Fig MW.10.1 and MW.10.2 shows these diversities respectively.
Frequency Diversity calls for use of two different frequencies for same MW link. This is normally
avoided because two frequency allocation means double the annual fee payable for frequency.
Frequency diversity is generally meant to overcome frequency interferences and various other
factors.
Space Diversity uses two MW antennas at each side and is best suited to overcome Reflection of
MW waves. Signal is received by both antennas called Main Antenna and Diversity Antenna and
it is IDU to decide which signal to receive. Generally IDU receives best possible signal. This
diversity also helps a lot in areas of high wind because if one antenna gets misaligned network
can function without fail from another. Thus this provides a sort of redundancy to our network.
15. FREE SPACE LOSS
Free Space Loss is defined as minimum loss an electromagnetic wave experiences if it travels in
atmosphere. It depends from place to place. Its value for Kerela and Rajasthan will be different
due to various factors one of which can be humidity. However, we may roughly define free
space loss for MW link as
Lfs = 92.45 + 20 log (dist * freq)
where
dist = MW hop length in Kms.
freq = Frequency of MW link in GHz.
EXAMPLE
For MW link of 15 GHz and hop length 10 Kms free space loss can roughly be calculated as
= 92.45 + 20 log ( 10 * 15)
= 135.97 dB
16. ANTENNA GAIN
Antenna Gain is the gain antenna provides to the signal before transmitting it into air. For
parabolic antennas used for MW link, this gain is roughly
Antenna Gain = 17.8 + 20 log (f * dia)
where
f = Frequency in GHz
dia = Diameter of MW antenna.
EXAMPLE
For 18 GHz MW link and 0.3 m size MW antenna, Antenna Gain will be approx
= 17.8 + 20 log (18*0.3)
= 32.44 dBi
(Don't worry about unit dBi, refer tutorial "Introduction to dB" elsewhere on this website. To
learn more about antennas refer tutorial on it.)
17. FRESNEL ZONE
To understand Fresnel zone we need to first refer Fig MW.12.1
From the figure above we can see that apart from direct line of sight (LOS) we need to leave
some space above and below it to allow deviation of MW wave from its original path. This
deviation, as already studied, is due to refraction. Fresnel zone is nothing but distance below
and above a point which should be clear for LOS communication.
where
rn = radius of fresnel zone. Generally we consider n=1 i.e. first fresnel zone clearance.
d1 = distance of point from Point A
d2 = distance of point from Point B
Lambda = Wavelength
Fig MW.12.1 MW Communication
18. LINK BUDGET
Now we will see link budget of MW link i.e. we will analyze gains and losses and calculate
received power at other end.
Refer Fig MW.13.1 before moving further.
Fig MW.13.1 Link Budget for MW Link
From Fig MW.13.1 it can be seen clearly that received power at Point B can be calculated as
RxA = TxA + GA - Lfs - Arain + GB
where
TxA = Transmit Power
GA = Gain of Antenna A
Lfs = Free Space Loss
Arain = Attenuation due to rain
GB = Gain of Antenna B
19. EXAMPLE
Suppose we have 6.2 GHz MW link. Diameter of antenna at both sides is 1.8 m. Distance is 20
Kms. Calculate approx received power at point B, if transmitted power at point A is 25 dBm.
SOLUTION
First we will calculate Gain of two antennas. Since diameter is same, both antennas will roughly
have gain of
= 17.8 + 20 log (freq * dia)
= 17.8 + 20 log (6.2 * 1.8)
= 38.753 dBi
Then, we will calculate rough free space loss as
= 98.45 + 20 log (dist * freq)
= 98.45 + 20 log (20 * 6.2)
= 140.318 dBm
Finally we will calculate received power at Point B from above given formula. We are assuming
rain attenuation as zero.
RxB = 25 + 38.753 - 140.318 - 0 + 38.753
= - 37.812 dBm Answer
NOTE
Receiver sensitivity is generally around -65 dBm and hence the receive power we are getting is
good and also take care of rain attenuation margin during rainy season. It is good practice to
leave around 30 dB as rain margin.