This document discusses microwave devices and systems. It begins with an overview of design methods and difficulties in microwave circuits. Key challenges include the distributed nature of components at microwave frequencies, which violates assumptions of lumped circuit theory. It then covers microwave systems, applications, and traveling wave concepts. Microwave systems are classified based on factors like frequency, distance, and capacity. Advantages include high bandwidth and line-of-sight transmission, while disadvantages include sensitivity to parasitic elements and atmospheric effects.
This document provides an overview of different transmission media used for data communication, including both guided and unguided media. It discusses various types of guided media such as twisted pair cables, coaxial cables, and fiber optic cables. It describes their characteristics, applications, advantages and disadvantages. The document also covers unguided or wireless transmission media such as radio waves, microwaves, and infrared. It explains propagation methods for unguided signals and the role of antennas. Finally, it discusses some issues with signal transmission such as attenuation, distortion and noise.
This document defines various types of computer networks and networking concepts. It begins by defining what a computer network is. It then lists and briefly describes different types of networks including personal area networks, local area networks, wireless local area networks, campus area networks, metropolitan area networks, wide area networks, and storage area networks. It also discusses network topologies such as bus, star, ring, mesh, tree, and hybrid topologies. Finally, it provides an overview of the seven-layer OSI model.
Transmission media is the physical medium used to transmit data between a sender and receiver. The two main types are guided and unguided media. Guided media uses physical pathways like cables to direct signals over shorter distances at high speeds securely. Common examples are twisted pair, coaxial, and fiber optic cables. Unguided media transmits electromagnetic waves without physical pathways, broadcasting signals through the air over longer distances less securely. Common examples are radio waves, microwaves, and infrared waves used in wireless technologies.
The document discusses recent advances in optical network technology, including components such as wavelength division multiplexing (WDM) systems, optical cross-connects, and optical switching technologies like MEMS. It outlines commercially available high-capacity optical systems providing terabits per second of capacity, as well as experimental WDM systems demonstrating multi-terabit capacities over long transmission distances. Emerging next generation optical networks are envisioned to be transparent, dynamic, and have switching at the wavelength level.
Network transmission involves sending signals over a medium to transmit information between nodes. There are two main types of signals: analog signals where voltage varies continuously and digital signals composed of discrete positive and zero voltages. Transmission can be unidirectional (simplex), allow communication in one direction at a time (half-duplex), or allow simultaneous bidirectional communication (full-duplex). Multiplexing allows multiple signals to travel together over one medium by separating them into logical subchannels. Wireless transmission uses infrared or radio frequency waves to transmit over the air without cables.
Transmission media are located below the physical layer and are used to transmit signals representing data. There are two main types of transmission media: guided media (wired), which provide a conduit for transmission, and unguided media (wireless), which transmit via electromagnetic waves without a physical pathway. Common guided media include twisted-pair cable, coaxial cable, and fiber-optic cable. Unguided media include radio waves, microwaves, and infrared. Each type of transmission media has different characteristics that determine its suitable uses.
This document discusses various types of transmission media and modes. It describes guided media like twisted pair cable, coaxial cable and fiber optic cable. It also describes unguided or wireless transmission media like radio waves, microwaves and infrared. For transmission modes, it explains serial vs parallel transmission and synchronous vs asynchronous transmission. Isochronous transmission with fixed bit transmission and equal gaps is also discussed.
International Journal of Engineering Research and Applications (IJERA) is a team of researchers not publication services or private publications running the journals for monetary benefits, we are association of scientists and academia who focus only on supporting authors who want to publish their work. The articles published in our journal can be accessed online, all the articles will be archived for real time access.
Our journal system primarily aims to bring out the research talent and the works done by sciaentists, academia, engineers, practitioners, scholars, post graduate students of engineering and science. This journal aims to cover the scientific research in a broader sense and not publishing a niche area of research facilitating researchers from various verticals to publish their papers. It is also aimed to provide a platform for the researchers to publish in a shorter of time, enabling them to continue further All articles published are freely available to scientific researchers in the Government agencies,educators and the general public. We are taking serious efforts to promote our journal across the globe in various ways, we are sure that our journal will act as a scientific platform for all researchers to publish their works online.
This document provides an overview of different transmission media used for data communication, including both guided and unguided media. It discusses various types of guided media such as twisted pair cables, coaxial cables, and fiber optic cables. It describes their characteristics, applications, advantages and disadvantages. The document also covers unguided or wireless transmission media such as radio waves, microwaves, and infrared. It explains propagation methods for unguided signals and the role of antennas. Finally, it discusses some issues with signal transmission such as attenuation, distortion and noise.
This document defines various types of computer networks and networking concepts. It begins by defining what a computer network is. It then lists and briefly describes different types of networks including personal area networks, local area networks, wireless local area networks, campus area networks, metropolitan area networks, wide area networks, and storage area networks. It also discusses network topologies such as bus, star, ring, mesh, tree, and hybrid topologies. Finally, it provides an overview of the seven-layer OSI model.
Transmission media is the physical medium used to transmit data between a sender and receiver. The two main types are guided and unguided media. Guided media uses physical pathways like cables to direct signals over shorter distances at high speeds securely. Common examples are twisted pair, coaxial, and fiber optic cables. Unguided media transmits electromagnetic waves without physical pathways, broadcasting signals through the air over longer distances less securely. Common examples are radio waves, microwaves, and infrared waves used in wireless technologies.
The document discusses recent advances in optical network technology, including components such as wavelength division multiplexing (WDM) systems, optical cross-connects, and optical switching technologies like MEMS. It outlines commercially available high-capacity optical systems providing terabits per second of capacity, as well as experimental WDM systems demonstrating multi-terabit capacities over long transmission distances. Emerging next generation optical networks are envisioned to be transparent, dynamic, and have switching at the wavelength level.
Network transmission involves sending signals over a medium to transmit information between nodes. There are two main types of signals: analog signals where voltage varies continuously and digital signals composed of discrete positive and zero voltages. Transmission can be unidirectional (simplex), allow communication in one direction at a time (half-duplex), or allow simultaneous bidirectional communication (full-duplex). Multiplexing allows multiple signals to travel together over one medium by separating them into logical subchannels. Wireless transmission uses infrared or radio frequency waves to transmit over the air without cables.
Transmission media are located below the physical layer and are used to transmit signals representing data. There are two main types of transmission media: guided media (wired), which provide a conduit for transmission, and unguided media (wireless), which transmit via electromagnetic waves without a physical pathway. Common guided media include twisted-pair cable, coaxial cable, and fiber-optic cable. Unguided media include radio waves, microwaves, and infrared. Each type of transmission media has different characteristics that determine its suitable uses.
This document discusses various types of transmission media and modes. It describes guided media like twisted pair cable, coaxial cable and fiber optic cable. It also describes unguided or wireless transmission media like radio waves, microwaves and infrared. For transmission modes, it explains serial vs parallel transmission and synchronous vs asynchronous transmission. Isochronous transmission with fixed bit transmission and equal gaps is also discussed.
International Journal of Engineering Research and Applications (IJERA) is a team of researchers not publication services or private publications running the journals for monetary benefits, we are association of scientists and academia who focus only on supporting authors who want to publish their work. The articles published in our journal can be accessed online, all the articles will be archived for real time access.
Our journal system primarily aims to bring out the research talent and the works done by sciaentists, academia, engineers, practitioners, scholars, post graduate students of engineering and science. This journal aims to cover the scientific research in a broader sense and not publishing a niche area of research facilitating researchers from various verticals to publish their papers. It is also aimed to provide a platform for the researchers to publish in a shorter of time, enabling them to continue further All articles published are freely available to scientific researchers in the Government agencies,educators and the general public. We are taking serious efforts to promote our journal across the globe in various ways, we are sure that our journal will act as a scientific platform for all researchers to publish their works online.
This document discusses different types of transmission media, including their characteristics and applications. It covers both guided media like twisted pair, coaxial cable, and optical fiber, as well as unguided or wireless transmission using radio frequencies, microwaves, and satellites. Key points discussed include the factors that determine transmission quality like bandwidth and interference, the advantages of higher bandwidth and fiber optics, and how different media are suited for various uses from local networks to long-distance trunks based on their data rates and transmission distances.
This document discusses the industrial application and maintenance procedures of optical fibers. It describes key telecom equipment like SMPS and battery vans that are used to power other equipment. It then explains the principles of optical fibers, describing the two main types - single mode and multi-mode fibers. The document outlines fiber installation steps and troubleshooting tools like OTDR and OPM. It details fiber splicing processes and the role of network management systems in monitoring networks.
Transmission media can be either wired (guided) or wireless (unguided) and are used to transmit signals from one device to another. Wired media include twisted pair, coaxial cable, and fiber optic cable. Wireless media transmit electromagnetic waves without a physical conductor and include radio waves, microwaves, and infrared. The type of media used depends on factors like bandwidth, distance, data rate, susceptibility to interference, and cost. Each media has its own advantages and limitations for different communication applications.
This document provides an overview of basic WDM optical networks. It describes WDM as a multiplexing technique that allows multiple wavelengths to be transmitted over the same fiber. There are two main architectures: broadcast and select, which uses a simple star topology, and wavelength routed, which establishes light paths between nodes using the same wavelength. The document outlines the key components and working principles of each architecture, including their advantages and disadvantages. Wavelength routed networks allow for wavelength reuse but require efficient wavelength assignment to avoid bandwidth loss.
Transmission media are located below the physical layer and are used to transmit signals representing data in the form of electromagnetic energy. There are two main types of transmission media: guided and unguided. Guided media like twisted pair cable, coaxial cable, and fiber optic cable provide a conduit for transmission. Factors like transmission rate, cost, environmental resistance, and distance must be considered when choosing a transmission medium. Twisted pair is the most commonly used guided medium and comes in shielded and unshielded varieties. Coaxial cable provides higher bandwidth but is more difficult to install. Fiber optic cable has the highest bandwidth but is also the most expensive. Unguided media like radio waves, infrared, and microwaves transmit
Optical multiplexers allow multiple signals to be transmitted simultaneously over a single optical fiber link. There are different optical multiplexing techniques, including wavelength division multiplexing (WDM) and optical time division multiplexing (OTDM). WDM assigns each signal a unique wavelength, while OTDM separates signals in the time domain. Optical multiplexers and demultiplexers use passive optical filters to combine and separate the wavelength signals. This increases bandwidth utilization and reduces transmission costs.
The document discusses different types of transmission media used to transmit data between devices. It defines transmission media as the means through which data is transformed from one place to another. Transmission media are broadly divided into guided media, which provide a physical path for signal propagation, and unguided media, which employ antennas to transmit through air. Common guided media include twisted pair cable, coaxial cable, and optical fiber cable. Common unguided media include microwave, infrared, and radio waves.
Communication – Basic process of exchanging information from one location (source) to destination (receiving end).
Refers – process of sending, receiving and processing of information/signal/input from one point to another point.
Electronic Communication System – defined as the whole mechanism of sending and receiving as well as processing of information electronically from source to destination.
Example – Radiotelephony, broadcasting, point-to-point, mobile communications, computer communications, radar and satellite systems.
1) There are two main categories of transmission media - guided and unguided. Guided media uses cabling to guide signals along a path, while unguided media transmits electromagnetic waves without a physical conductor.
2) Common guided media include twisted pair, coaxial cable, and optical fiber. Twisted pair has low bandwidth and is susceptible to interference, while coaxial cable and optical fiber can transmit signals over longer distances and have greater bandwidth.
3) Unguided or wireless transmission uses radio waves, microwaves, and infrared to transmit signals through the air without a physical path. It is available to anyone who can receive the signals.
A virtual LAN (VLAN) allows geographically dispersed network nodes to communicate as if they were on the same physical network by logically grouping nodes. A switch that supports VLANs allows the administrator to group specific switch ports together in a VLAN. Data passed between these ports will be isolated from other switch ports. Wired media like twisted pair wire, coaxial cable, and fiber optic cable can be used to physically connect network nodes, with each having advantages and disadvantages regarding attributes like noise absorption, bandwidth, and security.
This document discusses wavelength assignment algorithms in WDM optical networks. It compares the random wavelength assignment algorithm to the first-fit algorithm in terms of blocking probability. Blocking probability is lower with the first-fit algorithm compared to the random algorithm. The document also examines the impact of wavelength conversion capabilities (no conversion, partial conversion, and full conversion) on blocking probability. Blocking probability is lowest when full wavelength conversion is possible. The first-fit algorithm performs better than random assignment even without wavelength conversion capabilities.
Guided media such as twisted pair cable, coaxial cable, and optical fiber use physical paths to transmit electromagnetic signals representing data. Unguided or wireless media transmit signals through air without a physical path. Transmission is impaired by attenuation, distortion, and noise that degrade signals over distance. A variety of transmission media are used for different applications depending on their capabilities and limitations.
The document discusses different types of transmission media including guided media like twisted pair cable, coaxial cable, fiber optic cable and unguided media like radio waves, microwaves, and infrared. It provides details on each medium like their construction, applications, advantages and disadvantages. It also discusses concepts like propagation modes, transmission impairment and electromagnetic spectrum used for wireless communication. Satellite communication is discussed along with different types of satellites based on their orbit - geostationary, medium earth orbit and low earth orbit satellites.
This document discusses the use of subcarrier multiplexing (SCM) in optical communication networks. SCM allows a single lightwave carrier to transmit multiple communication channels by using different radio frequency subcarriers. Each receiver only needs to detect its assigned subcarrier rather than the full bandwidth. This improves receiver sensitivity and allows more users to be supported over a given fiber infrastructure. The document proposes a simple star coupler-based network using SCM that could support over 1000 users transmitting at 1.5 Mbps each. Limitations include the total usable bandwidth decreasing as more users are added. Overall, SCM provides an effective technique for building high-capacity optical access networks.
Transmission media are the means by which data is transmitted over long distances. Common transmission media include guided media like coaxial cable, twisted pair cable, and fiber optic cable as well as unguided or wireless media that transmit signals through air like radio waves, microwaves, and infrared. Each type of transmission medium has its own characteristics and applications. For example, coaxial cable provides good bandwidth and noise immunity but is more expensive than twisted pair cable. Fiber optic cable has the highest bandwidth but requires specialized equipment. Wireless transmission uses electromagnetic signals of varying frequencies that propagate through the air. [/SUMMARY]
This slide shows information on Guided and Unguided media in data communication and networking. things like types of cables for guided media and wireless routers for unguided media transfers
This document discusses different types of transmission media used for computer communications, including bounded and unbounded media. Bounded media, such as coaxial cable, twisted pair cable, and fiber optic cable, confine signals to a narrow path. Coaxial cable uses a central copper conductor surrounded by insulation and an outer copper shield. Twisted pair cable consists of pairs of copper wires twisted together. Fiber optic cable uses glass strands to transmit data via pulses of light. Unbounded media, also called wireless media, do not use physical connectors and can include radio waves, microwaves, and infrared waves for transmission.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
This document discusses PowerGrid's diversification into the telecom business under the brand PowerTel. It provides an overview of PowerGrid as the central transmission utility of India, carrying over 51% of the country's power. In 2001, PowerGrid diversified into telecom to utilize spare optic fiber capacity from its transmission infrastructure, providing telecom services across India. The document describes PowerTel's network and various telecom equipment used, and also discusses digital transmission systems like SDH and DWDM, fiber management, and troubleshooting techniques.
This document discusses transmission systems in satellite communications. It begins by defining a transmission line as a device that transmits or guides energy from one point to another. It then discusses how transmission lines carry alternating current and are used to connect radio transmitters and receivers. The document goes on to describe the key components of fiber optic and wireless transmission systems, including transmitters, receivers, optical fiber cables, antennas, and amplifiers. It explains how each component functions and its role in transmitting signals across long distances.
This document discusses different types of transmission media, including their characteristics and applications. It covers both guided media like twisted pair, coaxial cable, and optical fiber, as well as unguided or wireless transmission using radio frequencies, microwaves, and satellites. Key points discussed include the factors that determine transmission quality like bandwidth and interference, the advantages of higher bandwidth and fiber optics, and how different media are suited for various uses from local networks to long-distance trunks based on their data rates and transmission distances.
This document discusses the industrial application and maintenance procedures of optical fibers. It describes key telecom equipment like SMPS and battery vans that are used to power other equipment. It then explains the principles of optical fibers, describing the two main types - single mode and multi-mode fibers. The document outlines fiber installation steps and troubleshooting tools like OTDR and OPM. It details fiber splicing processes and the role of network management systems in monitoring networks.
Transmission media can be either wired (guided) or wireless (unguided) and are used to transmit signals from one device to another. Wired media include twisted pair, coaxial cable, and fiber optic cable. Wireless media transmit electromagnetic waves without a physical conductor and include radio waves, microwaves, and infrared. The type of media used depends on factors like bandwidth, distance, data rate, susceptibility to interference, and cost. Each media has its own advantages and limitations for different communication applications.
This document provides an overview of basic WDM optical networks. It describes WDM as a multiplexing technique that allows multiple wavelengths to be transmitted over the same fiber. There are two main architectures: broadcast and select, which uses a simple star topology, and wavelength routed, which establishes light paths between nodes using the same wavelength. The document outlines the key components and working principles of each architecture, including their advantages and disadvantages. Wavelength routed networks allow for wavelength reuse but require efficient wavelength assignment to avoid bandwidth loss.
Transmission media are located below the physical layer and are used to transmit signals representing data in the form of electromagnetic energy. There are two main types of transmission media: guided and unguided. Guided media like twisted pair cable, coaxial cable, and fiber optic cable provide a conduit for transmission. Factors like transmission rate, cost, environmental resistance, and distance must be considered when choosing a transmission medium. Twisted pair is the most commonly used guided medium and comes in shielded and unshielded varieties. Coaxial cable provides higher bandwidth but is more difficult to install. Fiber optic cable has the highest bandwidth but is also the most expensive. Unguided media like radio waves, infrared, and microwaves transmit
Optical multiplexers allow multiple signals to be transmitted simultaneously over a single optical fiber link. There are different optical multiplexing techniques, including wavelength division multiplexing (WDM) and optical time division multiplexing (OTDM). WDM assigns each signal a unique wavelength, while OTDM separates signals in the time domain. Optical multiplexers and demultiplexers use passive optical filters to combine and separate the wavelength signals. This increases bandwidth utilization and reduces transmission costs.
The document discusses different types of transmission media used to transmit data between devices. It defines transmission media as the means through which data is transformed from one place to another. Transmission media are broadly divided into guided media, which provide a physical path for signal propagation, and unguided media, which employ antennas to transmit through air. Common guided media include twisted pair cable, coaxial cable, and optical fiber cable. Common unguided media include microwave, infrared, and radio waves.
Communication – Basic process of exchanging information from one location (source) to destination (receiving end).
Refers – process of sending, receiving and processing of information/signal/input from one point to another point.
Electronic Communication System – defined as the whole mechanism of sending and receiving as well as processing of information electronically from source to destination.
Example – Radiotelephony, broadcasting, point-to-point, mobile communications, computer communications, radar and satellite systems.
1) There are two main categories of transmission media - guided and unguided. Guided media uses cabling to guide signals along a path, while unguided media transmits electromagnetic waves without a physical conductor.
2) Common guided media include twisted pair, coaxial cable, and optical fiber. Twisted pair has low bandwidth and is susceptible to interference, while coaxial cable and optical fiber can transmit signals over longer distances and have greater bandwidth.
3) Unguided or wireless transmission uses radio waves, microwaves, and infrared to transmit signals through the air without a physical path. It is available to anyone who can receive the signals.
A virtual LAN (VLAN) allows geographically dispersed network nodes to communicate as if they were on the same physical network by logically grouping nodes. A switch that supports VLANs allows the administrator to group specific switch ports together in a VLAN. Data passed between these ports will be isolated from other switch ports. Wired media like twisted pair wire, coaxial cable, and fiber optic cable can be used to physically connect network nodes, with each having advantages and disadvantages regarding attributes like noise absorption, bandwidth, and security.
This document discusses wavelength assignment algorithms in WDM optical networks. It compares the random wavelength assignment algorithm to the first-fit algorithm in terms of blocking probability. Blocking probability is lower with the first-fit algorithm compared to the random algorithm. The document also examines the impact of wavelength conversion capabilities (no conversion, partial conversion, and full conversion) on blocking probability. Blocking probability is lowest when full wavelength conversion is possible. The first-fit algorithm performs better than random assignment even without wavelength conversion capabilities.
Guided media such as twisted pair cable, coaxial cable, and optical fiber use physical paths to transmit electromagnetic signals representing data. Unguided or wireless media transmit signals through air without a physical path. Transmission is impaired by attenuation, distortion, and noise that degrade signals over distance. A variety of transmission media are used for different applications depending on their capabilities and limitations.
The document discusses different types of transmission media including guided media like twisted pair cable, coaxial cable, fiber optic cable and unguided media like radio waves, microwaves, and infrared. It provides details on each medium like their construction, applications, advantages and disadvantages. It also discusses concepts like propagation modes, transmission impairment and electromagnetic spectrum used for wireless communication. Satellite communication is discussed along with different types of satellites based on their orbit - geostationary, medium earth orbit and low earth orbit satellites.
This document discusses the use of subcarrier multiplexing (SCM) in optical communication networks. SCM allows a single lightwave carrier to transmit multiple communication channels by using different radio frequency subcarriers. Each receiver only needs to detect its assigned subcarrier rather than the full bandwidth. This improves receiver sensitivity and allows more users to be supported over a given fiber infrastructure. The document proposes a simple star coupler-based network using SCM that could support over 1000 users transmitting at 1.5 Mbps each. Limitations include the total usable bandwidth decreasing as more users are added. Overall, SCM provides an effective technique for building high-capacity optical access networks.
Transmission media are the means by which data is transmitted over long distances. Common transmission media include guided media like coaxial cable, twisted pair cable, and fiber optic cable as well as unguided or wireless media that transmit signals through air like radio waves, microwaves, and infrared. Each type of transmission medium has its own characteristics and applications. For example, coaxial cable provides good bandwidth and noise immunity but is more expensive than twisted pair cable. Fiber optic cable has the highest bandwidth but requires specialized equipment. Wireless transmission uses electromagnetic signals of varying frequencies that propagate through the air. [/SUMMARY]
This slide shows information on Guided and Unguided media in data communication and networking. things like types of cables for guided media and wireless routers for unguided media transfers
This document discusses different types of transmission media used for computer communications, including bounded and unbounded media. Bounded media, such as coaxial cable, twisted pair cable, and fiber optic cable, confine signals to a narrow path. Coaxial cable uses a central copper conductor surrounded by insulation and an outer copper shield. Twisted pair cable consists of pairs of copper wires twisted together. Fiber optic cable uses glass strands to transmit data via pulses of light. Unbounded media, also called wireless media, do not use physical connectors and can include radio waves, microwaves, and infrared waves for transmission.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
This document discusses PowerGrid's diversification into the telecom business under the brand PowerTel. It provides an overview of PowerGrid as the central transmission utility of India, carrying over 51% of the country's power. In 2001, PowerGrid diversified into telecom to utilize spare optic fiber capacity from its transmission infrastructure, providing telecom services across India. The document describes PowerTel's network and various telecom equipment used, and also discusses digital transmission systems like SDH and DWDM, fiber management, and troubleshooting techniques.
This document discusses transmission systems in satellite communications. It begins by defining a transmission line as a device that transmits or guides energy from one point to another. It then discusses how transmission lines carry alternating current and are used to connect radio transmitters and receivers. The document goes on to describe the key components of fiber optic and wireless transmission systems, including transmitters, receivers, optical fiber cables, antennas, and amplifiers. It explains how each component functions and its role in transmitting signals across long distances.
The document discusses various topics related to physical layer communication including:
1. Bandwidth-limited signals and the relationship between data rate and harmonics.
2. Different transmission media such as magnetic media, twisted pair, coaxial cable, and fiber optics. It describes their properties and applications.
3. Wireless transmission using different parts of the electromagnetic spectrum such as radio waves, microwaves, and infrared. It also discusses communication satellites.
The aim of this paper is to determine the viability of Indoor Optical Wireless Communication System. This paper introduces Visible Light Communication along with its merits, demerits and applications. Then the main characteristics of VLC system are described, around which the project is designed. Multiple Input-Multiple Output (MIMO) technique is used in the project in order to enhance the data rate of transmission. Instead of using a system of only one LED and one APD, which transmits only one bit at a time, a system of 4 LEDs and 4 APDs is introduced, which increases the data rates by 300% from the previous case. We observe the signal, noise, SNR, BER etc. across the room dimension. Finally, in the last chapter we summarize our results on the basis of MATLAB simulations and propose some modifications to this model that can be implemented in future.
This document provides an overview of telecommunication systems and network topologies. It discusses analog and digital signals, guided media like twisted pair, coaxial cable and fiber optics, and unguided media such as microwave, satellite and radio communication. It also describes common network topologies including bus, ring, star and mesh, and different types of networks like LAN, MAN and WAN. Specific LAN protocols and technologies covered include Ethernet, Fast Ethernet and Gigabit Ethernet. Peer-to-peer networks and examples of MAN and WAN uses are also summarized.
Telemetry is the process of measuring physical variables remotely and transmitting the data to another location for analysis and recording. The document discusses different types of telemetry including wire and wireless systems. It provides details on the components of a basic telemetry system such as transducers, conditioning circuits, modulators/encoders, transmitters, receivers, and demodulators. Wireless telemetry is commonly used for applications where the measurement area is not accessible, as it allows transmission over longer distances and at higher speeds compared to wire systems. Real-time telemetry is important for applications like aircraft testing where data is monitored during maneuvers from a safe ground station.
A new configuration of patch antenna array for rectenna array applicationsTELKOMNIKA JOURNAL
The performance and advantages of microstrip patch antennas made them a field of interest for wireless power transmission applications, especially for rectenna systems where the choice of the antenna is a crucial step. In this paper, a 5.8 GHz circularly polarized patch antenna has been designed and fabricated, then mounted by using 4 elements to achieve an antenna array to enhance the captured power to be converted by the rectifier circuit. The antenna array is well matched at 5.8 GHz in terms of reflection coefficient and has a directivity of 11 dB and a gain of 6 dB. Results have been confirmed by fabrication.
Challenging Issues in Inter-Satellite Optical Wireless Systems (IsOWC) and it...idescitation
Inter-satellite optical wireless communication
system (IsOWC), one of the important applications of FSO
(Free Space Optics) technology, will be deployed in space in
the near future because of providing power efficient and high
bandwidth allocation facilities unlike present microwave
satellite systems. In this paper, we have deliberated a
presentation of different challenging issues in achieving a
prolonged inter satellite link for an IsOWC system under
different situations and conditions. This work is also
emphasized on the suggested techniques to combat with the
degrading factors to put into practice of high speed IsOWC
system with minimum BER.
This document contains 25 questions and answers related to basic electronics and communication engineering. It covers topics such as the definitions of electronics, communication, engineering, and modulation. It also discusses different communication techniques like analog and digital, as well as modulation methods like AM, FM, and more. Additionally, it provides explanations for concepts like sampling, cut-off frequency, passband, stopband, and base stations.
This document discusses transmission fundamentals for data communications and networking. It defines key concepts such as data, signals, transmission, sources, destinations, and media. It explains how data can be transmitted through various media types including guided media like twisted pair, coaxial cable, and optical fiber as well as unguided media like radio waves, microwaves, and satellites. It also covers digital and analog signals, bandwidth, encoding data onto signals, and electromagnetic spectrum fundamentals.
This document contains 40 electronics interview questions covering topics such as basic electronics concepts, communication systems, modulation, demodulation, feedback, integrated circuits, and power systems. Some key questions addressed are: What is electronics? What is the difference between analog and digital communication? What is modulation and where is it utilized? What are common modulation techniques? What is the purpose of a base station? What is the difference between a repeater and an amplifier? What is an oscillator? What is an operational amplifier and what are its applications? What are the main divisions of a power system?
Designing an Antenna System That Can Perform Conditional RF to DC Harnessing ...IOSRJECE
Electromagnetic energy or RF energy will play a pivotal role in wireless technology and wireless communication in the impending future. The paper proposes a concept for a patch antenna based system that can harness RF energy upon triggering and can convert the harnessed RF to DC from the radio frequency of 1 GHz to 3 GHz, the design frequency is 2.4GHz. The patch antenna system contains a high gain patch antenna along with a wireless communicating module and a conversion circuit. The return loss of the antenna is approximately 27.1dB. The power gain is 30.1 dBm .The converter circuit is designed in), Multi-Sim to get an output voltage of around 5V that can be used to power a mobile-device or maybe stored in a battery. The triggering part is done with the help of a T-mote which is simulated in a network simulator, Cooja. The patch antenna is simulated in High Frequency Structural Simulator
The wireless Power Transmission is a useful and proper technology is used in various fields like electronic devices, implantable medical devices, industry and other fields, and has become a research hotspot at home and abroad. Because it enables the transmission of electrical energy from a power source to an electrical load across an air gap without interconnecting wires. This paper reviews the methods used in the wireless power transmission system, recent technologies, future and its application, merits as well as demerits. Mrs. Yogita Shailesh Kadam "Wireless Power Transmission System- A Review" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-7 | Issue-3 , June 2023, URL: https://www.ijtsrd.com.com/papers/ijtsrd57380.pdf Paper URL: https://www.ijtsrd.com.com/engineering/electrical-engineering/57380/wireless-power-transmission-system-a-review/mrs-yogita-shailesh-kadam
A Proximity based Retransmission Scheme for Power Line Ad-hoc LAN ijdpsjournal
Power line as an alternative for data transmission is being explored, and also being used to a certain extent. But from the data transfer point of view, power line, as a channel is highly dynamic and hence not quite suitable. To covert the office or home wiring system to a Local Area Network (LAN), adaptive
changes are to be made to the existing protocols. In this paper, a slotted transmission scheme is suggested, in which usable timeslots are found out by physically sensing the media. Common usable timeslots for the sender-receiver pair are used for communication. But these will not ensure safe packet
delivery since packets may be corrupted on the way during propagation from sender to receiver. Therefore, we also suggest a proximity based retransmission scheme where each machine in the LAN, buffers good packet and machines close to the receiver retransmit on receiving a NACK.
- NOMA is a non-orthogonal multiple access technology that can improve spectral efficiency by allowing all users to use all time-frequency resources simultaneously through techniques like power domain multiplexing and successive interference cancellation. However, it increases complexity.
- Full duplex technology aims to allow simultaneous uplink and downlink transmission but faces challenges from strong self-interference. Solutions involve antenna separation and self-interference cancellation.
- OAM uses the orbital angular momentum of electromagnetic waves to create orthogonal channels at the same frequency but faces challenges in application to cellular networks from atmospheric effects.
- Machine learning can optimize 5G across all layers to dynamically improve spectrum efficiency based on conditions.
1 . introduction to communication systemabhijitjnec
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1. •
•Microwave
Devices &
Systems
(ECEG4301)
Microwave Devices & Systems
Chapter-1
Microwave Circuit and Systems
Lecture -III
By
Yonas Desta (Lecturer)
Electronics & Communication Engineering
Stream
March 13, 2020 By: Yonas Desta (M.Sc.) 1
Aksum University
College of Engineering and Technology
Department of Electrical & Computer
Engineering
2. Contd…
Outline
• Design methods & difficulties
• Microwave Systems
• Microwave Applications
• Travelling waves and Transmission Line concepts
March 13, 2020 By: Yonas Desta (M.Sc.) 2
3. Design methods and Difficulties
Most design tools are available in many soft wares such as
Microwave harmonica, Libra, Empire, COMPACT(Computer Optimization of
Microwave Passive and Active CircuiTs) and Super COMPACT, Handy COMPACT ,
Touchstone , CADEC, Sonnet Software, Ansoft, Speedy, etc
We can design from analytical calculation of Maxwell’s equation applied to a
particular situation numerical solution using computers.
Difficulties Associated with the design
Because of the high frequencies (and short wavelengths), standard circuit
theory often cannot be used directly to solve microwave network problems.
In a sense, standard circuit theory is an approximation, or special case, of the
broader theory of electromagnetics as described by Maxwell’s equations [time-
varying currents → electromagnetic fields (or waves] ↔This is due to the
fact that, in general, the lumped circuit (L & C with low frequency)
element approximations of circuit theory may not be valid at high RF and
microwave frequencies.
March 13, 2020 By: Yonas Desta (M.Sc.) 3
4. Design methods and Difficulties
Microwave components often act as distributed elements, where the
phase of the voltage or current changes (Transmission line, Account for
propagation and time delays (phase change) significantly over the physical
extent of the device because the device dimensions are on the order of the
electrical wavelength.
At much lower frequencies the wavelength is large enough that there is
insignificant phase variation(negligible phase change) across the
dimensions of a component (lumped circuit)
The current and voltage along a transmission line may be considered
unchanged (which normally means the frequency is very low). The system
is called a lumped element system(Resistor, Capacitor, Inductor, Neglect
time delays (phase))
The current and voltage along a transmission line are functions of the
distance from the source (which normally means the frequency is high),March 13, 2020 By: Yonas Desta (M.Sc.) 4
5. Design methods and Difficulties
Conclusion:
Difficulties Associated with the design
I. Layout parasitic elements(electrical network) complicate the circuits basic
topology
• Parasitic inductance as main problem→Low value resistor
• Parasitic capacitance as main problem→ High value resistor
Parasitic elements) (electronics) A circuit element or property that is present
within an electrical component, and has a negative effect on the performance
of the circuit.
In electrical networks, a parasitic element is a circuit element that is possessed
by an electrical component but which it is not desirable for it to have for its
intended purpose. For instance, a resistor is designed to possess resistance,
but will also possess unwanted parasitic capacitance
⇒ Modeling of parasitic elements must be included in the layout
March 13, 2020 By: Yonas Desta (M.Sc.) 5
6. Design methods and Difficulties
Parasitic elements of a typical electronic component package
II. Active devices are not completely reproducible
Delivering/supplying energy to the external device.
(V source, I sources , battery sources, generators, transistors(can amplify
power of a signal)), and OP-Amps
III. Ckt element of microwave frequency are distributed in nature.
N.B.
The distributed nature of so called lumped elements must be considered
(Passive device).
⇒ A circuit element is lumped, if its physical length(𝒍) is much smaller than
the wave length of the highest signal operation → (high frequency signal)
March 13, 2020 By: Yonas Desta (M.Sc.) 6
7. Design methods and Difficulties
Example:
Consider the circuit below, having circuit 𝑙𝑒𝑛𝑔𝑡ℎ = 𝐿 = 5𝑐𝑚
Case (i): If 𝒇 = 𝟐𝟎 𝑲𝑯𝒛, 𝝀 =
𝒄
𝒇
=
𝟑𝑿𝟏𝟎 𝟖 𝒎/𝒔
𝟐𝟎𝒙𝟏𝟎 𝟑/𝒔
= 𝟏𝟓𝐱𝟏𝟎 𝟑
𝐦, hence
𝐿
λ
= 3.3𝑥10−6
≪ 1
i.e., The ckt length (𝟓𝒄𝒎) is very short as compared to 𝝀(𝟏𝟓𝐱𝟏𝟎 𝟑
𝐦), hence low
frequency approximations are applicable. ⇒[𝑉𝑜𝑢𝑡 = (
𝑅2
𝑅1 +𝑅2
) 𝑉𝑠]
Case (ii):
If 𝒇 = 𝟔 𝑮𝑯𝒛, 𝝀 =
𝒄
𝒇
=
𝟑𝑿𝟏𝟎 𝟏𝟎 𝒄𝒎/𝒔
𝟔𝒙𝟏𝟎 𝟗/𝒔
= 𝟓𝐜𝐦,
i.e., The circuit length is equal to wavelength (𝟓𝒄𝒎 = 𝟓𝒄𝒎) , so low frequency
approximations are not applicable.→(KCL, KVL) is not possible
March 13, 2020 By: Yonas Desta (M.Sc.) 7
8. Contd…
Case (iii):
If 𝑓 = 300 𝐺𝐻𝑧, 𝝀 =
𝒄
𝒇
=
𝟑𝑿𝟏𝟎 𝟏𝟎 𝒄𝒎/𝒔
𝟑𝟎𝟎𝒙𝟏𝟎 𝟗/𝒔
= 𝟎. 𝟏𝒄𝒎,
i.e., The circuit length is very long compared to wavelength (𝟓𝒄𝒎 > 𝟎. 𝟏𝒄𝒎) ,
so low frequency a approximations are not applicable.
Hence, for case (ii) and (iii)
I. Voltage on the line will be a function of position along the line (considered
changed due to high frequency) or (depends on functions of the distance
from the source ⇒ distributed element system.)
II. The circuit seen by the source presents a length dependent i/p
impedance, which must be carefully matched for efficient power transfer.
III. Dispersion of the signal will degrade before it reaches the o/p.
March 13, 2020 By: Yonas Desta (M.Sc.) 8
9. Microwave Systems
Earlier system used FDM voice (frequency-division multiplexing (FDM) is a
technique by which the total bandwidth available in a communication medium is
divided into a series of non-overlapping frequency bands each of which is used to
carry a separate signal. ⇒This allows a single transmission medium such as a cable
or optical fiber to be shared by multiple independent signals. Another use is to carry
separate serial bits or segments of a higher rate signal in parallel)band circuits and
used conventional non-coherent(In non coherent systems, the receiver
do not need the phase information of the transmitter carrier to recover the signal.
Do not require expensive and complex carrier recovery circuit. Lower bit error rate
of detection)frequency modulation techniques.⇒(better in band width and latency: is
generally measured in milliseconds 𝑚𝑠 and is unavoidable due to the way
networks communicate with each other, https://blog.stackpath.com/latency/
In frequency-division multiplexing (FDM), 12 𝑠𝑒𝑝𝑎𝑟𝑎𝑡𝑒 𝒗𝒐𝒊𝒄𝒆 signals, each of 4 −
𝑘𝑖𝑙𝑜ℎ𝑒𝑟𝑡𝑧 bandwidth, are modulated onto carrier waves in the 60– 108 − 𝑘𝑖𝑙𝑜ℎ𝑒𝑟𝑡𝑧
range. These modulated signals are combined to form a single complex groupMarch 13, 2020 By: Yonas Desta (M.Sc.) 9
10. Microwave Systems
Modern systems carry “Pulse Code Modulated TDM voice-band circuits use more
modern digital modulated techniques like phase shift keying(coherent system)
⇒(better in flexibility, efficiency and throughput: the rate at which data is transferred
through a system)
Coherent system: if each components is relevant and its structure function is
monotone, consists of components that, when working never harm the system and
improve the system in at least some instance. Thus, each working component is
beneficial to the system
A system is coherent if each of its components is relevant and its structure
function is monotone. A coherent system consists of components that, when
working, never harm the system and improve the system in at least some
instance. Thus, each working component is beneficial to the system.
Coherent system perform better than non-coherent systems, provided that the
receiver can faithfully reproduce the same chaotic basic signals sent by the
transmitter.
March 13, 2020 By: Yonas Desta (M.Sc.) 10
11. Microwave Systems
Microwave system depends on:
a) Frequency Characteristics:
Microwaves are very short frequency (as compared with ultra high radio waves
)radio waves that have many of the characteristics of light waves they travel in line
of sight paths and can be reflected and focused.
By focusing these ultra high radio waves in to a narrow beam, their energies are
connected and relatively low transmitting power is required for reliable transmission
over long distance.
b) System Capacity
The capacity of a microwave communication system varies from less than
𝟏𝟐 voice band channels to more than 𝟐𝟐𝟎𝟎𝟎 channels.
March 13, 2020 By: Yonas Desta (M.Sc.) 11
12. Microwave Systems
Working of Microwave System:
• Signal is transmitted through earth’s atmosphere. ⇒LOS
• Hence these systems have obvious advantage of carrying thousands of
information channels without the need for physical facilities such as co-
axial cables or optical fibers. ⇒it use Waveguide
Microwave communication systems are used to carry telephony,
television and data signals.
Majority of the system carry multi-channel telephone
signals(baseband).
Individual telephone channels, 4𝐾𝐻𝑧 wide are multiplexed together in a
multiplexer equipment to get base band.
At microwave due to high bandwidth capacity is more.
March 13, 2020 By: Yonas Desta (M.Sc.) 12
13. Microwave Systems
A microwave system normally consists of a transmitter subsystem and
receiver subsystem ,
Transmitter subsystem
Includes. Microwave oscillator(Generating frequency source such as audio
signal, reference signal, measurement), waveguides, and transmitting antenna
Receiver subsystem includes Receiving antenna, transmitting line or waveguide,
a microwave amplifier,(used for HPA at low microwave frequency) and receiver
Microwave system
March 13, 2020 By: Yonas Desta (M.Sc.) 13
14. Microwave Systems
Microwave source: includes
Semiconductor Devices (solid state devices)→Lower power microwave sources (High
Frequency)
Tube Devices →High power microwave sources (Low frequency)
Wave meter: a device which uses to measure microwave frequency
Calibrated attenuator: reflection free wave guide terminals in the form of dissipating
resistance , transmission of RF power in to thermal energy.(is an example of
kinetic energy, as it is due to the motion of particles, with motion being the key, results
in an object or a system having a temperature that can be measured, can be
transferred from one object or system to another in the form of heat)
RF reference used in the calibration gain /loss of other RF components /paths⇒ Used
to reduce the power
Power meter: an instrument which measures the
electrical power at microwave frequencies.
Crystal mount: Its function is to act as a demodulator, rectifying the radio signal,
converting it from alternating current to a pulsing direct current, to extract the audio signalMarch 13, 2020 By: Yonas Desta (M.Sc.) 14
15. Microwave Systems
Advantage of Microwave System
The gain of an antenna is proportional to its electrical size.
A 1% bandwidth provides more frequency range at microwave frequencies
than that of HF.
Microwave signals travel predominantly by LOS.
There is much less background noise at microwave frequencies than at RF.
Microwave systems do not require a right-of-way acquisition (finding new
way) between stations.
Fewer repeaters are necessary for amplification.
Underground facilities are minimized.
Increased reliability and less maintenance
March 13, 2020 By: Yonas Desta (M.Sc.) 15
16. Microwave Systems
Disadvantage of Microwave System
More difficult to analyze electronic circuits (Parasitic element)
Conventional components (resistors, inductors, and capacitors) cannot be
used at microwave frequencies(not be valid at high RF and microwave
frequencies)
There are physical limitations in creating resonant circuits at microwave
frequencies.
Conventional semi-conductor devices do not work properly at microwave
frequencies because of
Inherent inductances and capacitances of the terminal leads and
Transit time(The time required for an electron or other charge carrier to
travel between two electrodes in an electron tube or transistor)
For amplification, vacuum tubes are used such as klystrons, magnetrons
and traveling wave tubes (TWT).
Distance of operation is limited by line of sight (LOS).
Microwave signals are easily reflected and/or diverted because of the very
short wavelength.
Atmospheric conditions such as rain/fog can attenuate and absorb the
microwave signal especially at 20 GHz and up.
March 13, 2020 By: Yonas Desta (M.Sc.) 16
17. Microwave Communication Systems
What is micro wave communication
• A communication system that utilizes the radio frequency band spanning
2 𝑡𝑜 60 𝐺𝐻𝑧.
• As per IEEE, electromagnetic waves between 30 and 300 GHz are called
millimeter waves (MMW) instead of microwaves as their wavelengths are
about 1 to 10𝑚𝑚.
• Small capacity systems generally employ the frequencies less than 3 𝐺𝐻𝑧
• Medium and large capacity systems utilize frequencies ranging from 3 to
15 𝐺𝐻𝑧.
• Frequencies > 15 𝐺𝐻𝑧 are essentially used for short-haul transmission(b/c
its wave length is small)
March 13, 2020 By: Yonas Desta (M.Sc.) 17
18. Microwave Communication Systems
Classification of microwave
Nature
– Analog
– Digital
Distance / Frequency
– Short Haul
• used for short distance microwave transmission usually at lower
capacity ranging from 64 𝑘𝑏𝑝𝑠 𝑢𝑝 𝑡𝑜 2𝑀𝑏𝑝𝑠
– Medium Haul
– Long Haul
• used for long distance/multi-hop microwave transmission. Used for
backbone route applications at 34 𝑀𝑏𝑝𝑠 𝑡𝑜 620 Mbps capacity
Capacity / Bandwidth
– Light (Narrow Band)
– Medium (Narrow Band)
– Large (Wide Band)
March 13, 2020 By: Yonas Desta (M.Sc.) 18
19. Microwave Communication Systems
The main function of a microwave communication system is to ensure the
transmission of microwave signal from transmitter to receiver.
Microwave Communication Transmitter:
Block diagram of Microwave Transmitter
The transmitter consists of:
Information source(baseband i/p)
• Baseband signal processing unit (Pre-emphasis ntk, Pre-emphasis circuit is a high pass
filter or differentiator which allows high frequencies to pass):→ Overcoming obstacles ,
making advancement , it includes one , more or all of the following
An antialising,(minimizing distortion), ADC, Source coder, encryption unit(information to
make unreadable), error controller, multiplexer and a pulse shaper
March 13, 2020 By: Yonas Desta (M.Sc.) 19
20. Microwave Communication Systems
• The antialising filter and ADC(IFFT, changes frequency to time) are only
required if the information source is analogue such as speech signal.
Modulator :
The modulator impresses (processed) the baseband information on to the IF
carrier.→used b/c modulation, filtering and amplification are technologically
more difficult, and therefore more expensive, at the microwave RF)
BPF(IF Amplifier )
Stage of up conversion to the required RF(mixers + microwave oscillator) followed
by further filtering.⇒Up Converter: is a part to convert signal up for transmission.
Basically, mixer part for frequency upward conversion is called UP CONVERTER.
When input signal combines LO signal, RF signal is generated as much as input
signal with LO signal.
High power amplification(HPA) and Antenna
March 13, 2020 By: Yonas Desta (M.Sc.) 20
21. Microwave Communication Systems
Microwave Communication Receiver :
Block diagram of Microwave Receiver
The Receiver consists of
Antenna, Low nose amplifier (LAN, an electronic amplifier that amplifies a
very low-power signal without significantly degrading its signal-to-noise ratio,
Provides High-Quality RF & Microwave Components), Microwave filtering(BPF), Down
converter(is a part to convert RF signal down to IF or baseband. Basically, mixer
part for frequency downward is called down converter. When input signal combines
LO signal, IF or baseband signal is generated as much as Input signal to LO signal),
IF filtering and amplification, demodulator/detector, (Coherent or incoherent), baseband
processing unit (De-emphasis, de-emphasis circuit is a low pass filter or integrator which
allows only low frequencies to pass)
March 13, 2020 By: Yonas Desta (M.Sc.) 21
22. Microwave Communication Systems
Coherent signal/systems: need carrier phase in/on at the receiver and they used
matched filter to detect & decide what data was sent→same phase & freq →add up
constructively
Non-coherent: don't need carrier phase in/on & use method like square law to
recover the data → different phase & freq →
𝐶𝑎𝑛𝑐𝑒𝑙 𝑒𝑎𝑐ℎ 𝑜𝑡ℎ𝑒𝑟 𝑜𝑟 𝑓𝑎𝑑𝑖𝑛𝑔 𝑜𝑐𝑐𝑢𝑟𝑠 (random)
The signal processing unit will incorporate demultiplexing, error
detection/correction, deciphering (convert an encrypted or coded text or message
in to plain text) source decoding, DAC(FFT,(changes time to frequency,
appropriate), and audio/video amplification and filtering(appropriate).
If detection is coherent, phase locked loops (PLLs) is necessary
Example: Automatic gain control(AGC/AVC ,closed loop feedback regulating circuit amplifier uses
to maintain suitable signal amplitude at o/p), may be also present in the receiver
N.B:
The various sub systems of the above two figures (the devices comprising) them whetherMarch 13, 2020 By: Yonas Desta (M.Sc.) 22
23. Microwave Communication Systems
Types Of Microwave Stations
Terminals
are points in the system where the baseband signals either originate or
terminate
Repeaters
are points in the system where the baseband signals maybe reconfigured
or simply repeated or amplified.
Passive Microwave repeaters
• A device that re-radiates microwave energy without additional electronic
power.
– back to back
– billboard type
Active Microwave repeater
• A receiver and a transmitter placed back to back or in tandem with the
system.
• It receives the signal, amplifies and reshapes it, then retransmits the signalMarch 13, 2020 By: Yonas Desta (M.Sc.) 23
24. Microwave Communication Systems
Depending upon the stage at which they amplify the signal, the repeaters
can be classified into following three types
IF repeaters
Baseband Repeaters
RF repeaters
.
Repeater stations
• Points in a system where baseband signals may be reconfigured.
• Points in a system where RF/IF carriers are simply "repeated" or
amplified.
March 13, 2020 By: Yonas Desta (M.Sc.) 24
25. Microwave Communication Systems
Microwave IF Repeater
Called heterodyne repeaters⇒works at the level of intermediate frequency (IF)
Received RF carrier is down-converted to an IF frequency only,
amplified, reshaped, up-converted to an RF frequency, and then
retransmitted.
.
March 13, 2020 By: Yonas Desta (M.Sc.) 25
26. Microwave Communication Systems
IF section
• Generates a frequency-modulated IF carrier.(found in Heterodyne
receiver)
RF section.
• The IF signal enters the transmitter through a protection switch.
• The IF and compression amplifiers help keep the IF signal power constant
and at approximately the required input level to the transmit modulator
(transmod).
Transmod
• A balanced modulator that, when used in conjunction with a microwave
generator, power amplifier, and Band pass filter, up-converts the IF carrier
to an RF carrier and amplifies the RF to the desired output power.
Microwave generator
• Provides the RF carrier input to the up-converter.
• It is called a microwave generator rather than an oscillator because it is
difficult to construct a stable circuit that will oscillate in the gigahertz range.
March 13, 2020 By: Yonas Desta (M.Sc.) 26
27. Microwave Communication Systems
Microwave Baseband repeaters:
• The received RF carrier is down-converted to an IF frequency, amplified, filtered,
and then further demodulated to baseband.
• The baseband signal, which is typically frequency-division-multiplexed voice-band
channels, is further modulated to a master group, super group, group, or even
channel level.⇒ amplified and converted back to IF and finally to RF signals ⇒
amplified signal is Retransmitted
.
March 13, 2020 By: Yonas Desta (M.Sc.) 27
28. Contnd
Microwave RF repeater
• The received microwave signal is not down-converted to IF or baseband
levels.
• The signal is simply mixed (heterodyned) with a local oscillator frequency in
a nonlinear mixer.⇒Converted to out put radio
frequency⇒amplified⇒Retransmitted
March 13, 2020 By: Yonas Desta (M.Sc.) 28
29. Why are microwave frequencies of interest?
Perhaps the best way of answering this is to consider a primary application
of microwaves -- wireless communication
The first application of microwaves that often comes to mind is wireless
transmission of information. As we go higher in frequency, fractional
bandwidth increases.
Example:
let’s assume that we wish to transmit a number of 4 𝑘𝐻𝑧 wide voice signals
through a wireless link. Further let’s assume that we have two wireless
systems to chose from, one operating at 500 𝑀𝐻𝑧 and the second at 4 𝐺𝐻𝑧,
each with a 10 % 𝑏𝑎𝑛𝑑𝑤𝑖𝑑𝑡ℎ around its center frequency.
In theory, the 500 𝑀𝐻𝑧 system could carry:
𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑐ℎ𝑎𝑛𝑛𝑒𝑙𝑠 =
𝒐𝒑𝒆𝒓𝒂𝒕𝒊𝒏𝒈 𝒇𝒓𝒆𝒒𝒖𝒆𝒏𝒄𝒚 ∗ 𝒑𝒆𝒓𝒄𝒆𝒏𝒕 𝑩𝑾
𝑩𝑾 𝒑𝒆𝒓 𝒄𝒉𝒂𝒏𝒏𝒆𝒍
=
𝟎. 𝟓𝑮𝑯𝒛 ∗ 𝟎. 𝟏
𝟒𝑲𝑯𝒛
=
𝟏𝟐, 𝟓𝟎𝟎 𝑪𝒉𝒂𝒏𝒏𝒆𝒍𝒔
For 4GHz
𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑐ℎ𝑎𝑛𝑛𝑒𝑙𝑠 =
𝒐𝒑𝒆𝒓𝒂𝒕𝒊𝒏𝒈 𝒇𝒓𝒆𝒒𝒖𝒆𝒏𝒄𝒚 ∗ 𝒑𝒆𝒓𝒄𝒆𝒏𝒕 𝑩𝑾
𝑩𝑾 𝒑𝒆𝒓 𝒄𝒉𝒂𝒏𝒏𝒆𝒍
=
𝟒𝑮𝑯𝒛 ∗ 𝟎. 𝟏
𝟒𝑲𝑯𝒛
= 𝟏𝟎𝟎, 𝟎𝟎𝟎
March 13, 2020 By: Yonas Desta (M.Sc.) 29
30. Why are microwave frequencies of interest?
• From the above, we see that as the system’s operating frequency
increases, ideally its capacity increases.
• Another advantage in going to higher frequency is antenna size.
• For a given aperture size, the gain of an antenna increases with frequency.
• To make portable wireless communications possible, we must operate at a
frequency at which the required antenna size is reasonable
• Another advantage of increased antenna gain with frequency is the
potential for higher-resolution imaging systems.
• While it may seem that one can simply increase the operating frequency of
a microwave link to increase capacity, issues such as equipment cost,
spectrum licensing, and atmospheric attenuation must be considered.
March 13, 2020 By: Yonas Desta (M.Sc.) 30
31. Contnd
Conclusion:
Advantages of using higher frequency
Larger instantaneous bandwidth for much information
Higher resolution for radar imaging and sensing
Less interference by near by application
Higher speed for digital communication, signal processing and
transmission
Less crowded spectrum
Difficulty in jamming (military application)
Disadvantages of using high frequency
More expensive component
Higher atmospheric loss
Reliance in GaAs technology rather than Si technology
Higher component losses, lower output power from active devices
March 13, 2020 By: Yonas Desta (M.Sc.) 31
32. Applications of Microwaves
Microwaves have a wide range of applications in modern technology
Most common applications are with in the range 𝟏𝑮𝑯𝒛 𝒕𝒐 𝟒𝟎 𝑮𝑯𝒛
1. Broadcasting and Telecommunication Transmission
Due to their short wavelength, highly directional antennas are smaller
Mobile phone network, like GSM, use the low microwave/UHF frequencies
around 1.8 𝑎𝑛𝑑 1.9𝐺𝐻𝑧
Intercontinental Telephone and TV, space communication (Earth – to –
space and space – to – Earth), telemetry communication link for railways
etc.
Microwave used in television signal to transmit a signal from a remote
location to a television station from a specially equipped van
Used for communication, from one point to another via satellite
Satellite TV either operates in the C band for the traditional large dish fixed
March 13, 2020 By: Yonas Desta (M.Sc.) 32
33. Applications of Microwaves
2. Remote Sensing
Radars (Radio detection and ranging) : uses a transmitter to illuminate an object
and a receiver to detect its position & velocity, detect aircraft, track / guide
supersonic missiles, observe and track weather patterns, air traffic control
(ATC), burglar alarms, garage door openers, police speed detectors , radio
astronomy (sub class of astronomy that studies celestial(sky /space)objects at radio
frequencies etc.
3.Home, Commercial and industrial applications
Microwave energy is a means for rapid heating and excellent processing efficiency
Microwave cooking, Oven
Drying machines – textile, food and paper industry for drying clothes, potato chips,
printed matters etc.
Food process industry – Precooling /cooking, pasteurization/sterility, hat frozen/
refrigerated precooled meats, roasting of food grains / beans.March 13, 2020 By: Yonas Desta (M.Sc.) 33
34. Applications of Microwaves
Biomedical Applications (diagnostic/therapeutic ) – diathermy for
localized superficial heating, deep electromagnetic heating for treatment of
cancer, hyperthermia ( local, regional or whole body for cancer therapy).
Rubber industry / plastics / chemical / forest product industries
Mining / public works, breaking rocks, tunnel boring, drying /
breaking up concrete, breaking up coal seams, curing of cement.
Drying inks /drying textiles, drying / sterilizing grains, drying /
sterilizing pharmaceuticals, leather, tobacco, power transmission.
4. Microwave semiconductor
Light generated charge carriers in a microwave semiconductor make it
possible to create a whole new world of microwave devices, fast jitter free
switches, phase shifters, HF generators, etc.
March 13, 2020 By: Yonas Desta (M.Sc.) 34
35. Contnd
Travelling waves and Transmission Line
A travelling wave may be defined by
𝑬 𝒛, 𝒕 = 𝑬 𝒐 𝒄𝒐𝒔(𝜔𝒕 − 𝒌𝒛)
Due to the variation of 𝑬 with both time 𝒕 and space variable 𝒛, we may
plot 𝑬 as a function of 𝒕 by keeping 𝒛 constant and vice versa.
Where
𝑬 𝒐 is amplitude, 𝜔 is angular frequency (𝜔 = 2𝜋𝑓), λ wave length in meter, 𝒕 is
time in sec, 𝒛 is 𝒛 -axis, displacement on 𝒛 -axis(space on 𝒛 ), 𝑘 is constant
(propagation constant or wave number.), 𝒗 𝒑 is velocity of the wave or phase
velocityMarch 13, 2020 By: Yonas Desta (M.Sc.) 35
36. Contnd
If 𝑓 is low , 𝑇 is high, 𝜔 is low, so Phase variation is negligible⇒(Lumped
parameters, R,L,C are used ) and (Ohms low, KCL, KVL used)
If 𝑓 is high , 𝜔 is high , hence phase variation is high ⇒ Distributed
Parameters ⇒( R/unit length , C/unit length, L/unit length) are used ⇒
microwave components
Propagation constant=wave no. =
𝟐𝝅
𝝀
= 𝒌
Velocity of the propagation wave = phase velocity= 𝒗 𝒑 =
𝜔
𝒌
=
𝟐𝝅𝒇
(
𝟐𝝅
𝝀
)
= 𝒇𝝀 = 𝒇𝒖𝑻 =
March 13, 2020 By: Yonas Desta (M.Sc.) 36
Path travelled by wave Phase change
λ 2𝜋
𝜆/2 𝜋
λ/4 𝜋/2
L ∆𝟇=(2𝜋/λ)*L=(k)*L, 2𝜋/λ is Propagation constant
37. Contnd
Free space Intrinsic impedance =𝞰 𝒐 =
𝝁 𝒐
𝜺 𝒐
=
𝟒𝝅∗𝟒∗𝟏𝟎−𝟕 𝑯/𝒎
𝟖.𝟖𝟓𝟒∗𝟏𝒐−𝟏𝟐 𝑭/𝒎
= 𝟑𝟕𝟕Ω
𝒄 = 𝒗𝒆𝒍𝒐𝒄𝒊𝒕𝒚 𝒐𝒇 𝒍𝒊𝒈𝒉𝒕 =
𝟏
𝝁 𝒐 𝜺 𝒐
𝒊𝒏 𝒗𝒂𝒄𝒖𝒎
Intrinsic impedance of the medium = 𝞰 =
𝝁
𝜺
or
Wave impedance =
𝑬
𝑯
= intrinsic impedance of medium
March 13, 2020 By: Yonas Desta (M.Sc.) 37
38. Contnd
Transmission Line:
A transmission line is the structure that forms all or part of a path from
one place to another for directing the transmission of energy, such as
electrical power transmission and microwaves.
Conventional two-conductor transmission lines are commonly used for
transmitting microwave energy.
If a line(Txn line) is properly matched to its characteristic impedance (𝑧) at
each terminal, its efficiency can reach a maximum
Transmission lines are commonly met on printed-circuit boards.
A microwave integrated circuit
March 13, 2020 By: Yonas Desta (M.Sc.) 38
39. Contnd
Fundamental mode
(A) Transverse Electric Mode (TEM): 𝑬 𝒛𝒔 = 𝟎 𝑯 𝒛𝒔 ≠ 𝟎
The electric field, 𝑬 is transverse to the direction of propagation of wave
and the magnetic field, 𝑯 has components transverse and in the direction
of the wave.
• Exists in waveguide modes.
(B)Transverse Magnetic Mode (TMM): 𝑬 𝒛𝒔 ≠ 𝟎, 𝑯 𝒛𝒔 = 𝟎
The magnetic field, 𝑯 is transverse to the direction of propagation of wave
and the electric field, 𝑬 has components transverse and in the direction of
the wave.March 13, 2020 By: Yonas Desta (M.Sc.) 39
40. Contnd
(C) Transverse Electromagnetic (TEM)
• The electric field, 𝑬 and the magnetic field, 𝑯 are oriented (direct towards)
transverse to the direction of propagation of wave.
• Exists in plane waves and transmission lines (2 conductors).
• No cut-off frequency.
(D) quasi-TEM mode :
If the wavelength larger than the cut-off wavelength or
non-uniform dielectric constant
March 13, 2020 By: Yonas Desta (M.Sc.) 40
41. Contnd
• Important transmission lines classified according to the number of
conductors they contain, and according to the general class of
electromagnetic wave or propagation ‘mode’ that they support.
Metal and dielectric can be represented by:
has no conductors at all – it is just a rod of dielectric, but it can still trap and
guide an electromagnetic wave. This is extremely important practically in
the form of an optical fiber. It can also be used at ‘high’ radio frequencies,
i.e. in microwave or millimetre-wave bands, when it would be referred to as
a ‘dielectric waveguide’.
There is no very obvious way we could apply concepts like voltage and
March 13, 2020 By: Yonas Desta (M.Sc.) 41
42. Contnd
A transmission line with only one conductor – a conventional rectangular
waveguide.
Finline or ‘𝐸 − 𝑝𝑙𝑎𝑛𝑒’ structure. Here there is a central section with a
printed conductor pattern, lending itself to the production of a microwave
integrated circuit. This is considered an attractive structure for work at
millimetric frequencies.
The enclosed structure of the coaxial cable, largely prevents this and
makes it suitable as a general-purpose radio frequency line.
March 13, 2020 By: Yonas Desta (M.Sc.) 42
43. Contnd
• The parallel wire line, may be seen in old-fashioned open telephone lines,
overhead power lines (electric power txn & distribution to transmit elec
energy along large distance), and sometimes as lines connecting high-
power, low and medium frequency radio transmitters to their antennas.
• In the figure we have a structure suitable for microwave integrated circuits,
where the ‘live’ conductor may be given a complex pattern by printed circuit
methods. However, it is mechanically awkward to include other electronic
components in it and to assemble.
• Suitability for ‘printed’ production methods and microwave integrated
circuits (MICs) while avoiding the mechanical drawbacks of stripline .
Microstrip, is by far the most widely used.
March 13, 2020 By: Yonas Desta (M.Sc.) 43
44. Contnd
Suitability for ‘printed’ production methods and microwave integrated circuits
(MICs) while avoiding the mechanical drawbacks of stripline . Is gaining in
popularity.
Suitability for ‘printed’ production methods and microwave integrated circuits (MICs)
while avoiding the mechanical drawbacks of stripline. Is used only for a few special
purposes.
Suitability for ‘printed’ production methods and microwave integrated circuits
(MICs) while avoiding the mechanical drawbacks of stripline. Especially useful
March 13, 2020 By: Yonas Desta (M.Sc.) 44
45. Contnd
⇒ The line in figure is a variant of the parallel wire line where the mechanical support is
built in. It is mainly used for relatively short runs linking radio equipment and antennas
at VHF frequencies.
⇒Note that, in the microstrip form of line, it is easy to break the ‘live’ conductor in order
to insert a component in series with it, but if we want to connect a component in shunt
between the live conductor and ground, we have to cut or drill the dielectric. Coplanar
waveguide and coplanar strips do not suffer from this problem.
⇒ The slot line, in the figure, can be, and is, used for complex MICs but it remains
rather specialized and is not particularly easy to use.
⇒ Slot line, in the figure looks as though it should be classed as a quasi-TEM line, and it would
support DC excitation. It turns out, however, to be a special case that is not adequately described
by quasi-TEM mode theory. (This is because the conductors are nominally infinite in extent. ⇒(the
magnetic field lines in the slot line mode cannot form complete loops in a transverse
plane, because they would have to penetrate the conductors to do so.)
March 13, 2020 By: Yonas Desta (M.Sc.) 45
46. Contnd
⇒The following important points can be made about the classification of
transmission lines:
1. All the two-conductor lines (except slotline), and only these, are classified
as transverse electromagnetic (TEM), or quasi-TEM mode, lines.
2. The lines in this class can be recognized as those that could carry DC
excitation(producing a electrical magnetic field, to provide a continuous (DC)
current to the field) and which conform to the idea of a complete circuit with
‘go’ and ‘return’ conductors(form complete loops )
3. In the two-conductor family, TEM lines can be recognized as those in which
the dielectric constant is uniform over the cross-section of the line, while
those with a non-uniform dielectric are quasi-TEM lines.
(In a few special cases, magnetic materials may also be involved, and here
the permeability also has to be uniform for a true TEM line.)
A further important point is that:
4. All the TEM and quasi-TEM lines can treated, to a good first approximation
at least, by distributed circuit theory
March 13, 2020 By: Yonas Desta (M.Sc.) 46