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.
Chap 02 antenna & wave propagation EngkaderAMuse
This document summarizes key concepts about antennas and wireless signal propagation. It discusses different types of antennas like dipole antennas and parabolic reflective antennas. It also describes the main modes of wireless signal propagation including ground-wave propagation, sky-wave propagation, and line-of-sight propagation. Additionally, it outlines several factors that can impair wireless signals during propagation, such as attenuation, noise, multipath, and atmospheric absorption.
This document provides an overview of key concepts in antennas and propagation. It defines an antenna as a device that transmits or receives electromagnetic waves. It describes common antenna types like dipoles and parabolic reflectors. It also covers topics like radiation patterns, antenna gain, propagation modes (ground wave, sky wave, line-of-sight), free space loss, noise, multipath, and techniques to mitigate signal degradation like diversity and error correction.
This document discusses antennas and propagation. It begins by defining antennas and their use for transmission and reception of electromagnetic energy. It then describes common antenna types including dipole antennas and parabolic reflective antennas. The document discusses concepts like antenna gain, effective area, and the relationship between them. It also covers propagation modes including ground-wave, sky-wave, and line-of-sight propagation. Key challenges like multipath propagation, fading, and different types of noise are summarized. Finally, it discusses techniques to compensate for errors during transmission.
This document discusses line-of-sight (LOS) radio propagation. It defines LOS propagation as occurring when frequencies are above 30 MHz, where signals travel in straight lines between antennas without being reflected by the ionosphere. It describes how the maximum distance of LOS propagation, known as the radio horizon, is determined by the curvature of the Earth and the heights of the transmitting and receiving antennas. It also discusses factors that can impair LOS wireless transmission, such as free space loss, scattering, atmospheric absorption, ducting, refraction, reflection, and shadowing effects.
Ground waves propagate along the Earth's surface and are used for medium wave (MW) transmissions. Space waves travel in straight lines but are limited by the curvature of the Earth. Sky waves are used for short wave (SW) transmissions and reflect off the ionosphere which consists of layers (D, E, F1, F2) that vary in density and thickness depending on the time of day and sun exposure. Different propagation modes are used depending on the frequency band and conditions to maximize transmission range.
Radio waves can propagate between two points through four main ways: directly, following the curvature of the Earth, becoming trapped in the atmosphere, or refracting off the ionosphere. Propagation modes include ground-wave, sky-wave, and space-wave propagation. Mobile radio propagation is influenced by factors like reflections, scattering, diffraction, and the electromagnetic properties of materials. Proper propagation modeling is important for wireless system design and performance.
Critical frequency is the maximum frequency that can be reflected by a layer of the ionosphere at vertical incidence. It is different for different ionosphere layers and is proportional to the square root of the maximum electron density in that layer. The critical frequency changes throughout the day and due to atmospheric conditions, making higher frequencies better during the day and lower frequencies better at night. Given the maximum electron density, the critical frequency can be calculated using the formula: fc = 9√Nm, where fc is the critical frequency in MHz and Nm is the maximum electron density in electrons per cubic meter.
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.
Chap 02 antenna & wave propagation EngkaderAMuse
This document summarizes key concepts about antennas and wireless signal propagation. It discusses different types of antennas like dipole antennas and parabolic reflective antennas. It also describes the main modes of wireless signal propagation including ground-wave propagation, sky-wave propagation, and line-of-sight propagation. Additionally, it outlines several factors that can impair wireless signals during propagation, such as attenuation, noise, multipath, and atmospheric absorption.
This document provides an overview of key concepts in antennas and propagation. It defines an antenna as a device that transmits or receives electromagnetic waves. It describes common antenna types like dipoles and parabolic reflectors. It also covers topics like radiation patterns, antenna gain, propagation modes (ground wave, sky wave, line-of-sight), free space loss, noise, multipath, and techniques to mitigate signal degradation like diversity and error correction.
This document discusses antennas and propagation. It begins by defining antennas and their use for transmission and reception of electromagnetic energy. It then describes common antenna types including dipole antennas and parabolic reflective antennas. The document discusses concepts like antenna gain, effective area, and the relationship between them. It also covers propagation modes including ground-wave, sky-wave, and line-of-sight propagation. Key challenges like multipath propagation, fading, and different types of noise are summarized. Finally, it discusses techniques to compensate for errors during transmission.
This document discusses line-of-sight (LOS) radio propagation. It defines LOS propagation as occurring when frequencies are above 30 MHz, where signals travel in straight lines between antennas without being reflected by the ionosphere. It describes how the maximum distance of LOS propagation, known as the radio horizon, is determined by the curvature of the Earth and the heights of the transmitting and receiving antennas. It also discusses factors that can impair LOS wireless transmission, such as free space loss, scattering, atmospheric absorption, ducting, refraction, reflection, and shadowing effects.
Ground waves propagate along the Earth's surface and are used for medium wave (MW) transmissions. Space waves travel in straight lines but are limited by the curvature of the Earth. Sky waves are used for short wave (SW) transmissions and reflect off the ionosphere which consists of layers (D, E, F1, F2) that vary in density and thickness depending on the time of day and sun exposure. Different propagation modes are used depending on the frequency band and conditions to maximize transmission range.
Radio waves can propagate between two points through four main ways: directly, following the curvature of the Earth, becoming trapped in the atmosphere, or refracting off the ionosphere. Propagation modes include ground-wave, sky-wave, and space-wave propagation. Mobile radio propagation is influenced by factors like reflections, scattering, diffraction, and the electromagnetic properties of materials. Proper propagation modeling is important for wireless system design and performance.
Critical frequency is the maximum frequency that can be reflected by a layer of the ionosphere at vertical incidence. It is different for different ionosphere layers and is proportional to the square root of the maximum electron density in that layer. The critical frequency changes throughout the day and due to atmospheric conditions, making higher frequencies better during the day and lower frequencies better at night. Given the maximum electron density, the critical frequency can be calculated using the formula: fc = 9√Nm, where fc is the critical frequency in MHz and Nm is the maximum electron density in electrons per cubic meter.
Space wave propagation involves radio waves that travel directly or after reflecting off the Earth's surface within the lower 20 km of the atmosphere. These waves can propagate line-of-sight between transmitter and receiver antennas in the VHF and UHF bands. Space waves follow two paths - direct or ground reflected - and may arrive in or out of phase, causing signal fluctuations. The maximum transmission distance is limited by the Earth's curvature and obstructions that can cause shadowing effects. Refractive phenomena like super-refraction can sometimes extend the radio horizon.
Weather & environmental changes affect RF signal severely. Ducting is one of the environmental phenomena that heavily deteriorate the radio performance. This document will give some ideas on root cause, impact & solutions of ducting on Radio Performance.
Radio waves can propagate through free space or be guided by surfaces like the ground or the ionosphere. The key layers of the ionosphere that influence radio propagation are the D, E, and F layers. The F layer, consisting of the F1 and F2 sublayers, is the most important for long-distance radio communications as it remains partially ionized at night. Radio signals can be reflected or refracted by the ionized layers of the ionosphere, allowing skywave propagation over long distances beyond the horizon.
The document summarizes key concepts about radio wave propagation including:
- Radio waves are transmitted from antennas and can propagate through line of sight transmission, reflection off the ionosphere (skywaves), or along the ground (groundwaves).
- The ionosphere, ionized by solar radiation, is made up of layers (D, E, F1, F2) that refract radio waves to different extents based on frequency and solar activity.
- Solar activity and sunspots influence ionization and radio propagation, with higher activity providing better long-distance propagation via skywaves.
Communication System Theory for JEE Main 2015 Ednexa
There are three main types of space communication: ground wave propagation, sky wave propagation, and space wave propagation. Ground wave propagation uses low frequencies between 500kHz to 1500kHz for medium wave radio transmission over short distances. Sky wave propagation uses very low and high frequency waves that can reflect off the ionosphere to allow long distance communication. Space wave propagation uses electromagnetic waves between 30MHz to 300MHz that travel directly between transmitting and receiving antennas within line of sight of each other over distances up to 35km. Satellite communication is used to transmit waves beyond 30MHz that cannot be transmitted through other methods. Satellites receive, amplify, and retransmit signals to allow global communication with advantages like long distance coverage and ability to transmit large
1) The document is a lesson on acoustics that discusses sound fundamentals like frequency, wavelength, decibels and the human range of hearing.
2) It then covers acoustic concepts such as power, intensity, impedance and how they relate to a vibrating surface like a panel.
3) The document focuses on calculating the radiated acoustic power from a panel using Rayleigh's integral formulation and defines terms like transmission loss and radiation efficiency.
1) The document discusses parameters used to characterize mobile multipath channels including power delay profile, mean excess delay, RMS delay spread, maximum excess delay, coherence bandwidth, Doppler spread, and coherence time.
2) These parameters are derived from the power delay profile and describe aspects of the channel such as time dispersion, frequency selectivity, and time variation due to Doppler shift.
3) Examples of typical values for different channel parameters are given for outdoor and indoor mobile radio channels.
This document discusses radio frequency (RF) concepts including:
- RF refers to electromagnetic frequencies between 3 kHz and 300 GHz used in radio and radar. RF currents have special properties like flowing along conductor surfaces (skin effect) and radiating energy as electromagnetic waves.
- RF currents can cause burns but often do not cause a painful electric shock sensation due to their high frequency. Their ability to flow through insulating materials like capacitors decreases with increasing frequency.
- Factors that impact RF signals include free space loss as signals spread out, skin effect, absorption from the environment, and reflection from objects. Impedance matching is important to minimize signal reflections from impedance mismatches.
- Noise is an unwanted signal
Terrestrial microwave communication uses high-frequency radio waves to transmit data between two fixed points using antennas with a direct line-of-sight. It operates between 2-60 GHz and requires repeaters for long distances. Key advantages are fast deployment, flexibility, and ability to link across obstacles. Design considerations include ensuring the Fresnel zone around the beam path is clear of obstacles to minimize signal diffraction and interference. Link budgets calculate total gains and losses to determine maximum transmission distances.
This document summarizes a thesis presentation on simulating indoor and outdoor radio wave propagation using MATLAB. The presentation covers propagation mechanisms like line of sight, reflection, refraction, scattering and diffraction. It describes simulating these mechanisms using MATLAB to calculate received power and signal strength. Validation of the simulation model is done by considering free space propagation. Indoor ray propagation is also simulated to analyze coverage using line of sight and multiple reflections.
The document discusses three modes of electromagnetic wave propagation:
1) Surface wave propagation involves waves traveling along the Earth's surface and is suitable for local broadcasting up to 2MHz.
2) Space wave propagation includes direct, ground-reflected, and tropospheric waves not subjected to ground absorption. It is used for FM radio and TV signals over line-of-sight distances.
3) Sky wave propagation uses reflection from the ionosphere to transmit signals from 3-30MHz over long distances but is unreliable due to weather variations.
The document discusses key concepts related to antennas and electromagnetic waves. It defines that radio waves have electric and magnetic fields that are perpendicular to each other and the direction of wave propagation. It also describes how antennas can transmit electromagnetic waves by converting electrical energy to radio waves and receive waves by converting radio waves back to electrical energy. Antenna size is inversely proportional to frequency, with higher frequencies requiring smaller antennas. Antenna radiation patterns and near/far field regions are also discussed.
Wireless communication transfers information between points without a wired connection. A transmitter sends electromagnetic waves through the air medium to a receiver. Radio propagation allows signals to travel from the transmitter in three modes: direct, ground wave, and sky wave. Multipath propagation occurs when signals reach the receiver along multiple paths, which can cause constructive or destructive interference. Fading describes signal attenuation over time due to factors like multipath delay spread, Doppler spread from mobility, rain, obstacles, and frequency. Shadowing also reduces signal strength from blockage by objects along the transmission path.
This document summarizes several statistical distributions used to model fading in wireless communication channels: Rician, Rayleigh, and lognormal distributions. It describes the Rayleigh distribution as modeling channels without a line-of-sight component, where the received signal envelope follows a Rayleigh distribution. The Rician distribution models channels with a dominant line-of-sight component, reducing to a Rayleigh distribution when the line-of-sight component fades. It also briefly discusses the Okumura and Hata propagation path loss models used for cellular system design.
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 discusses electromagnetic waves and their propagation. It begins by defining electromagnetic waves and their properties such as being transverse waves that propagate through free space at the speed of light. It then discusses how EM waves spread uniformly in all directions from a point source, forming spherical wavefronts. The document goes on to describe different types of EM wave propagation including ground waves, space waves, and sky waves that propagate via reflection off the ionosphere. Key factors that influence EM wave propagation like frequency, transmitter power, and atmospheric conditions are also summarized.
Small scale fading and multipath measurementsVrince Vimal
1. The document discusses small-scale fading and multipath measurements in wireless channels. It describes how fading occurs due to interference from multiple copies of transmitted signals arriving at the receiver at different times.
2. Key channel parameters that influence fading are discussed, including multipath propagation, Doppler shift caused by mobility, and signal bandwidth. Multipath signals have random amplitudes and phases that cause constructive and destructive interference as the receiver moves.
3. Techniques for measuring small-scale fading and multipath include using direct radio frequency pulses or spread spectrum channel sounding with a sliding correlator. Parameters extracted from power delay profiles include mean excess delay, root mean square delay spread, and coherence bandwidth.
This document discusses electromagnetic wave propagation. It begins by defining electromagnetic waves and their properties like frequency, intensity, and direction of travel. It then discusses different types of electromagnetic waves like radio waves. Key concepts covered include polarization, rays and wavefronts, the electric and magnetic fields, characteristic impedance, inverse square law, attenuation, refraction, reflection, diffraction, interference, and terrestrial propagation through surface waves and sky waves. Sky wave propagation is explained in detail, covering the ionosphere layers, critical frequency, critical angle, virtual height, and skip distance.
This document discusses radio frequency circuits. It begins by introducing radio frequency and defining the frequency ranges. It then discusses different RF circuit components like amplifiers, oscillators, and mixers. It explains the effects of high frequency on circuit design and components. Different circuit topologies for narrowband and wideband amplifiers are described, along with classes of amplifier operation. Construction techniques for RF circuits involving shielding and bypassing are covered. The document also discusses frequency multipliers, mixers, and RF system concepts like tuning and neutralization.
The document discusses key parameters for characterizing multipath channels:
1) Coherence bandwidth is the range of frequencies over which the channel can be considered flat and two frequency components will be correlated. It is inversely proportional to the root mean square (RMS) delay spread.
2) Doppler spread is the range of frequencies over which the received Doppler spectrum is non-zero. It characterizes the time-varying nature of the channel.
3) Coherence time is the duration over which the amplitude of two received signals will be correlated. It is inversely proportional to the maximum Doppler shift and characterizes the time-varying nature of the channel.
This document discusses various topics related to antennas and propagation. It describes what antennas are, their characteristics, and different types of antennas like dipole, parabolic, and arrays. It also covers radiation patterns, antenna gain, and different propagation modes like ground wave, sky wave, and line-of-sight. Key factors affecting line-of-sight transmission are discussed, including attenuation, free space loss, noise from thermal, intermodulation, crosstalk and impulse sources, and atmospheric absorption and multipath effects. Common antenna types and their uses as well as concepts like radiation patterns, antenna gain, and propagation modes are summarized.
This document discusses signals and signal propagation in wireless communication networks. It covers several key topics:
1. Signals are the physical representation of data that is transmitted through communication systems. Signal parameters like amplitude, frequency, and phase shift encode the data.
2. Signals propagate through wireless networks differently than through wired networks due to effects like reflection, scattering, diffraction and multipath propagation. This results in delayed and attenuated signals arriving at the receiver.
3. Techniques like TDMA, CDMA and multiple access protocols are used to allow multiple users to share the same wireless medium and communicate simultaneously. Fixed and dynamic channel allocation schemes are discussed.
Space wave propagation involves radio waves that travel directly or after reflecting off the Earth's surface within the lower 20 km of the atmosphere. These waves can propagate line-of-sight between transmitter and receiver antennas in the VHF and UHF bands. Space waves follow two paths - direct or ground reflected - and may arrive in or out of phase, causing signal fluctuations. The maximum transmission distance is limited by the Earth's curvature and obstructions that can cause shadowing effects. Refractive phenomena like super-refraction can sometimes extend the radio horizon.
Weather & environmental changes affect RF signal severely. Ducting is one of the environmental phenomena that heavily deteriorate the radio performance. This document will give some ideas on root cause, impact & solutions of ducting on Radio Performance.
Radio waves can propagate through free space or be guided by surfaces like the ground or the ionosphere. The key layers of the ionosphere that influence radio propagation are the D, E, and F layers. The F layer, consisting of the F1 and F2 sublayers, is the most important for long-distance radio communications as it remains partially ionized at night. Radio signals can be reflected or refracted by the ionized layers of the ionosphere, allowing skywave propagation over long distances beyond the horizon.
The document summarizes key concepts about radio wave propagation including:
- Radio waves are transmitted from antennas and can propagate through line of sight transmission, reflection off the ionosphere (skywaves), or along the ground (groundwaves).
- The ionosphere, ionized by solar radiation, is made up of layers (D, E, F1, F2) that refract radio waves to different extents based on frequency and solar activity.
- Solar activity and sunspots influence ionization and radio propagation, with higher activity providing better long-distance propagation via skywaves.
Communication System Theory for JEE Main 2015 Ednexa
There are three main types of space communication: ground wave propagation, sky wave propagation, and space wave propagation. Ground wave propagation uses low frequencies between 500kHz to 1500kHz for medium wave radio transmission over short distances. Sky wave propagation uses very low and high frequency waves that can reflect off the ionosphere to allow long distance communication. Space wave propagation uses electromagnetic waves between 30MHz to 300MHz that travel directly between transmitting and receiving antennas within line of sight of each other over distances up to 35km. Satellite communication is used to transmit waves beyond 30MHz that cannot be transmitted through other methods. Satellites receive, amplify, and retransmit signals to allow global communication with advantages like long distance coverage and ability to transmit large
1) The document is a lesson on acoustics that discusses sound fundamentals like frequency, wavelength, decibels and the human range of hearing.
2) It then covers acoustic concepts such as power, intensity, impedance and how they relate to a vibrating surface like a panel.
3) The document focuses on calculating the radiated acoustic power from a panel using Rayleigh's integral formulation and defines terms like transmission loss and radiation efficiency.
1) The document discusses parameters used to characterize mobile multipath channels including power delay profile, mean excess delay, RMS delay spread, maximum excess delay, coherence bandwidth, Doppler spread, and coherence time.
2) These parameters are derived from the power delay profile and describe aspects of the channel such as time dispersion, frequency selectivity, and time variation due to Doppler shift.
3) Examples of typical values for different channel parameters are given for outdoor and indoor mobile radio channels.
This document discusses radio frequency (RF) concepts including:
- RF refers to electromagnetic frequencies between 3 kHz and 300 GHz used in radio and radar. RF currents have special properties like flowing along conductor surfaces (skin effect) and radiating energy as electromagnetic waves.
- RF currents can cause burns but often do not cause a painful electric shock sensation due to their high frequency. Their ability to flow through insulating materials like capacitors decreases with increasing frequency.
- Factors that impact RF signals include free space loss as signals spread out, skin effect, absorption from the environment, and reflection from objects. Impedance matching is important to minimize signal reflections from impedance mismatches.
- Noise is an unwanted signal
Terrestrial microwave communication uses high-frequency radio waves to transmit data between two fixed points using antennas with a direct line-of-sight. It operates between 2-60 GHz and requires repeaters for long distances. Key advantages are fast deployment, flexibility, and ability to link across obstacles. Design considerations include ensuring the Fresnel zone around the beam path is clear of obstacles to minimize signal diffraction and interference. Link budgets calculate total gains and losses to determine maximum transmission distances.
This document summarizes a thesis presentation on simulating indoor and outdoor radio wave propagation using MATLAB. The presentation covers propagation mechanisms like line of sight, reflection, refraction, scattering and diffraction. It describes simulating these mechanisms using MATLAB to calculate received power and signal strength. Validation of the simulation model is done by considering free space propagation. Indoor ray propagation is also simulated to analyze coverage using line of sight and multiple reflections.
The document discusses three modes of electromagnetic wave propagation:
1) Surface wave propagation involves waves traveling along the Earth's surface and is suitable for local broadcasting up to 2MHz.
2) Space wave propagation includes direct, ground-reflected, and tropospheric waves not subjected to ground absorption. It is used for FM radio and TV signals over line-of-sight distances.
3) Sky wave propagation uses reflection from the ionosphere to transmit signals from 3-30MHz over long distances but is unreliable due to weather variations.
The document discusses key concepts related to antennas and electromagnetic waves. It defines that radio waves have electric and magnetic fields that are perpendicular to each other and the direction of wave propagation. It also describes how antennas can transmit electromagnetic waves by converting electrical energy to radio waves and receive waves by converting radio waves back to electrical energy. Antenna size is inversely proportional to frequency, with higher frequencies requiring smaller antennas. Antenna radiation patterns and near/far field regions are also discussed.
Wireless communication transfers information between points without a wired connection. A transmitter sends electromagnetic waves through the air medium to a receiver. Radio propagation allows signals to travel from the transmitter in three modes: direct, ground wave, and sky wave. Multipath propagation occurs when signals reach the receiver along multiple paths, which can cause constructive or destructive interference. Fading describes signal attenuation over time due to factors like multipath delay spread, Doppler spread from mobility, rain, obstacles, and frequency. Shadowing also reduces signal strength from blockage by objects along the transmission path.
This document summarizes several statistical distributions used to model fading in wireless communication channels: Rician, Rayleigh, and lognormal distributions. It describes the Rayleigh distribution as modeling channels without a line-of-sight component, where the received signal envelope follows a Rayleigh distribution. The Rician distribution models channels with a dominant line-of-sight component, reducing to a Rayleigh distribution when the line-of-sight component fades. It also briefly discusses the Okumura and Hata propagation path loss models used for cellular system design.
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 discusses electromagnetic waves and their propagation. It begins by defining electromagnetic waves and their properties such as being transverse waves that propagate through free space at the speed of light. It then discusses how EM waves spread uniformly in all directions from a point source, forming spherical wavefronts. The document goes on to describe different types of EM wave propagation including ground waves, space waves, and sky waves that propagate via reflection off the ionosphere. Key factors that influence EM wave propagation like frequency, transmitter power, and atmospheric conditions are also summarized.
Small scale fading and multipath measurementsVrince Vimal
1. The document discusses small-scale fading and multipath measurements in wireless channels. It describes how fading occurs due to interference from multiple copies of transmitted signals arriving at the receiver at different times.
2. Key channel parameters that influence fading are discussed, including multipath propagation, Doppler shift caused by mobility, and signal bandwidth. Multipath signals have random amplitudes and phases that cause constructive and destructive interference as the receiver moves.
3. Techniques for measuring small-scale fading and multipath include using direct radio frequency pulses or spread spectrum channel sounding with a sliding correlator. Parameters extracted from power delay profiles include mean excess delay, root mean square delay spread, and coherence bandwidth.
This document discusses electromagnetic wave propagation. It begins by defining electromagnetic waves and their properties like frequency, intensity, and direction of travel. It then discusses different types of electromagnetic waves like radio waves. Key concepts covered include polarization, rays and wavefronts, the electric and magnetic fields, characteristic impedance, inverse square law, attenuation, refraction, reflection, diffraction, interference, and terrestrial propagation through surface waves and sky waves. Sky wave propagation is explained in detail, covering the ionosphere layers, critical frequency, critical angle, virtual height, and skip distance.
This document discusses radio frequency circuits. It begins by introducing radio frequency and defining the frequency ranges. It then discusses different RF circuit components like amplifiers, oscillators, and mixers. It explains the effects of high frequency on circuit design and components. Different circuit topologies for narrowband and wideband amplifiers are described, along with classes of amplifier operation. Construction techniques for RF circuits involving shielding and bypassing are covered. The document also discusses frequency multipliers, mixers, and RF system concepts like tuning and neutralization.
The document discusses key parameters for characterizing multipath channels:
1) Coherence bandwidth is the range of frequencies over which the channel can be considered flat and two frequency components will be correlated. It is inversely proportional to the root mean square (RMS) delay spread.
2) Doppler spread is the range of frequencies over which the received Doppler spectrum is non-zero. It characterizes the time-varying nature of the channel.
3) Coherence time is the duration over which the amplitude of two received signals will be correlated. It is inversely proportional to the maximum Doppler shift and characterizes the time-varying nature of the channel.
This document discusses various topics related to antennas and propagation. It describes what antennas are, their characteristics, and different types of antennas like dipole, parabolic, and arrays. It also covers radiation patterns, antenna gain, and different propagation modes like ground wave, sky wave, and line-of-sight. Key factors affecting line-of-sight transmission are discussed, including attenuation, free space loss, noise from thermal, intermodulation, crosstalk and impulse sources, and atmospheric absorption and multipath effects. Common antenna types and their uses as well as concepts like radiation patterns, antenna gain, and propagation modes are summarized.
This document discusses signals and signal propagation in wireless communication networks. It covers several key topics:
1. Signals are the physical representation of data that is transmitted through communication systems. Signal parameters like amplitude, frequency, and phase shift encode the data.
2. Signals propagate through wireless networks differently than through wired networks due to effects like reflection, scattering, diffraction and multipath propagation. This results in delayed and attenuated signals arriving at the receiver.
3. Techniques like TDMA, CDMA and multiple access protocols are used to allow multiple users to share the same wireless medium and communicate simultaneously. Fixed and dynamic channel allocation schemes are discussed.
Signals are the physical representation of data that is transmitted through communication systems. They are functions of time and location, with parameters like amplitude, frequency, and phase that represent the data. Periodic signals like sine waves are commonly used as carriers for radio transmission. Signals can be represented in the time domain, frequency domain, or phase domain. Propagation effects like path loss, reflection, diffraction, and scattering impact radio signals as they travel from the transmitter to the receiver.
1. The document discusses key principles of electromagnetic radiation and antenna fundamentals, including: principles of EM fields, propagation modes, antenna characterization methods, and factors that determine antenna performance such as polarization, gain, beamwidth.
2. It introduces common antenna types like dipole and discusses how antenna design balances factors like directivity, bandwidth, and radiation pattern.
3. Testing methods are outlined to characterize antennas and adjust transmitters/receivers without interfering radiation.
This document discusses key concepts related to electromagnetic radiation and antenna characterization. It begins with an overview of the principles of EM radiation and how moving electric and magnetic fields produce EM waves. It then covers propagation of EM waves along wires and the use of dipole antennas to transmit radiation through standing wave resonance. The document also introduces different antenna types and polarization, as well as the major modes of propagation including ground waves, sky waves, space waves, and satellite waves. It concludes with a discussion of antenna characterization through far-field radiation pattern measurements and the use of polar plots to visualize antenna gain.
This document provides an overview of key concepts in mobile computing. It discusses:
1) Modes of evaluation including problem-based learning, continuous assessments, and term-end exams.
2) Types of mobility including user mobility (e.g. Vodafone services) and device mobility (e.g. mobile phones).
3) Characteristics of communication devices ranging from fixed/wired to mobile/wireless and applications of mobile technologies in various domains like vehicles, emergencies, and replacing wired networks.
This document discusses various aspects of signal propagation including:
1. It defines transmission, detection, and interference ranges for signal propagation. Receiving power decreases with distance and is influenced by factors like fading, shadowing, and reflection.
2. It describes three main propagation modes - ground-wave propagation below 2MHz, sky-wave propagation between 2-30MHz using ionosphere reflection, and line-of-sight propagation above 30MHz requiring direct path.
3. Key challenges for wireless signals include multipath propagation causing interference, and fading effects from mobility and environment that impact power levels over time. Error correction and adaptive equalization techniques aim to overcome these issues.
This document discusses various aspects of signal propagation including:
1. It defines transmission, detection, and interference ranges for wireless signals. The receiving power decreases with distance and is influenced by factors like fading, shadowing, reflection, refraction, scattering, and diffraction.
2. It describes three main propagation modes - ground-wave propagation below 2MHz, sky-wave propagation between 2-30MHz using ionospheric reflection, and line-of-sight propagation above 30MHz requiring a direct path.
3. Factors that impair line-of-sight wireless transmission include attenuation, free space loss, atmospheric absorption, multipath effects, noise, and mobility-induced fading. Techniques like error correction and
Thermal noise from components and the environment is a major source of noise in satellite communication systems. Noise comes from internal components as well as external sources like the sun, atmosphere, and space. The signal-to-noise ratio indicates the strength of the signal relative to noise, with a higher ratio desired. Forward error correction, adaptive equalization, and diversity techniques can help compensate for noise and other issues like fading that affect signal quality. Maintaining stability, power supply, and operating in the harsh environment of space present ongoing challenges for satellite systems.
This document provides an overview of key concepts in antennas and propagation. It defines an antenna as a device that transmits or receives electromagnetic waves. It describes common antenna types like dipoles and parabolic reflectors. It also covers topics like radiation patterns, antenna gain, propagation modes (ground wave, sky wave, line-of-sight), factors that affect signal strength over distance like free space loss and multipath, and techniques to mitigate noise and fading like diversity and error correction.
This document discusses various topics related to antennas and propagation. It begins by defining an antenna and its roles in transmission and reception of electromagnetic energy. It then describes common antenna types including dipole antennas, quarter-wave vertical antennas, and parabolic reflective antennas. The document also covers propagation modes such as ground-wave, sky-wave, and line-of-sight propagation. Additional topics discussed include antenna gain and effective area, various sources of noise and signal impairments like multipath propagation and fading, and techniques to compensate for errors.
EM waves can transmit information via three main methods: point-to-point transmission, broadcast transmission, and three ways to send signals by propagating parallel to the Earth's surface, refracting due to the curve of the Earth, or propagating along the Earth's surface. EM waves have the property of diffraction that causes them to bend, and can reflect off the ionosphere up to 300 km above the Earth's surface to transmit signals over greater ranges than line-of-sight propagation allows, enabling technologies like geostationary satellites and global broadcasting.
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 summarizes key concepts about antennas and propagation. It discusses the basic functions and types of antennas, including radiation patterns and gain. It also covers propagation modes like ground-wave, sky-wave and line-of-sight. Factors that affect transmission like free space loss, noise and multipath interference are explained. Error compensation techniques such as forward error correction, equalization and diversity are also summarized.
Wireless channels in wireless communicationPreciousMposa1
The document discusses various wireless channel characteristics including large scale path loss models, small scale fading parameters, and multipath effects. It describes free space path loss and the two-ray ground reflection model for large scale path loss. For small scale fading, it discusses parameters such as coherence bandwidth and Doppler spread/coherence time that characterize multipath time delay spread and Doppler spread fading. It also summarizes multipath delay spread which occurs when a signal takes multiple paths causing interference from delayed components.
The document discusses several factors that affect space wave propagation:
1. Curvature of the earth and its imperfections can create shadow zones and reduce transmission distance.
2. The earth's roughness and imperfections cause the amplitude of the ground reflected wave to be smaller than the direct ray.
3. Hills, buildings, and other obstacles can obstruct the radio path between transmitter and receiver.
4. The field strength varies with height above the earth, exhibiting maxima, minima and nulls depending on frequency, transmitter height, and wave polarization.
This document provides an overview of types of antennas and propagation modes. It discusses how antennas work to transmit and receive radio waves, and describes common types of antennas including omnidirectional antennas that radiate in all directions and directional antennas that preferentially radiate in a particular direction. It also summarizes the three main propagation modes: ground waves that hug the Earth's surface, space waves that travel in straight lines, and sky waves that reflect off the ionosphere. Key factors that determine the propagation path are frequency, atmospheric conditions, and time of day.
This document discusses electromagnetic wave propagation. Electromagnetic waves consist of oscillating electric and magnetic fields that propagate through space at the speed of light. They include radio waves, light, X-rays and gamma rays. Radio waves propagate through space as transverse electromagnetic waves and their speed depends on the medium. The wavelength is determined by the frequency and phase velocity. Power density decreases with distance from the source according to the inverse square law. Reflection, refraction, diffraction and polarization affect wave propagation. Terrestrial propagation is influenced by the curvature of the Earth and the atmosphere, especially the ionosphere.
Radio waves are a form of electromagnetic radiation that are produced when an electric current oscillates in an antenna. They can carry data by modulating the wave, such as by changing its amplitude, frequency, or phase. Common modulation techniques include AM, FM, PSK, and FSK. Multiplexing allows multiple signals to be transmitted simultaneously over the same medium by allocating unique resources like frequency bands or time slots. Multiple access protocols like FDMA, TDMA, and CDMA are used to avoid interference from other users transmitting in the same spectrum.
1. Radio uses electromagnetic waves to transmit signals through air using a transmitter and receiver. Sound is converted to electromagnetic waves using modulation like AM and FM.
2. A radio receiver receives radio waves via an antenna and converts them back into audio using demodulation after tuning, amplification and detection stages. Superheterodyne receivers improve reception by translating the radio frequency to an intermediate frequency using beat frequencies.
3. FM receivers use a discriminator circuit for demodulation instead of a detector, as it is better for detecting small frequency differences representing the audio signal.
Harnessing WebAssembly for Real-time Stateless Streaming PipelinesChristina Lin
Traditionally, dealing with real-time data pipelines has involved significant overhead, even for straightforward tasks like data transformation or masking. However, in this talk, we’ll venture into the dynamic realm of WebAssembly (WASM) and discover how it can revolutionize the creation of stateless streaming pipelines within a Kafka (Redpanda) broker. These pipelines are adept at managing low-latency, high-data-volume scenarios.
Presentation of IEEE Slovenia CIS (Computational Intelligence Society) Chapte...University of Maribor
Slides from talk presenting:
Aleš Zamuda: Presentation of IEEE Slovenia CIS (Computational Intelligence Society) Chapter and Networking.
Presentation at IcETRAN 2024 session:
"Inter-Society Networking Panel GRSS/MTT-S/CIS
Panel Session: Promoting Connection and Cooperation"
IEEE Slovenia GRSS
IEEE Serbia and Montenegro MTT-S
IEEE Slovenia CIS
11TH INTERNATIONAL CONFERENCE ON ELECTRICAL, ELECTRONIC AND COMPUTING ENGINEERING
3-6 June 2024, Niš, Serbia
International Conference on NLP, Artificial Intelligence, Machine Learning an...gerogepatton
International Conference on NLP, Artificial Intelligence, Machine Learning and Applications (NLAIM 2024) offers a premier global platform for exchanging insights and findings in the theory, methodology, and applications of NLP, Artificial Intelligence, Machine Learning, and their applications. The conference seeks substantial contributions across all key domains of NLP, Artificial Intelligence, Machine Learning, and their practical applications, aiming to foster both theoretical advancements and real-world implementations. With a focus on facilitating collaboration between researchers and practitioners from academia and industry, the conference serves as a nexus for sharing the latest developments in the field.
Advanced control scheme of doubly fed induction generator for wind turbine us...IJECEIAES
This paper describes a speed control device for generating electrical energy on an electricity network based on the doubly fed induction generator (DFIG) used for wind power conversion systems. At first, a double-fed induction generator model was constructed. A control law is formulated to govern the flow of energy between the stator of a DFIG and the energy network using three types of controllers: proportional integral (PI), sliding mode controller (SMC) and second order sliding mode controller (SOSMC). Their different results in terms of power reference tracking, reaction to unexpected speed fluctuations, sensitivity to perturbations, and resilience against machine parameter alterations are compared. MATLAB/Simulink was used to conduct the simulations for the preceding study. Multiple simulations have shown very satisfying results, and the investigations demonstrate the efficacy and power-enhancing capabilities of the suggested control system.
Embedded machine learning-based road conditions and driving behavior monitoringIJECEIAES
Car accident rates have increased in recent years, resulting in losses in human lives, properties, and other financial costs. An embedded machine learning-based system is developed to address this critical issue. The system can monitor road conditions, detect driving patterns, and identify aggressive driving behaviors. The system is based on neural networks trained on a comprehensive dataset of driving events, driving styles, and road conditions. The system effectively detects potential risks and helps mitigate the frequency and impact of accidents. The primary goal is to ensure the safety of drivers and vehicles. Collecting data involved gathering information on three key road events: normal street and normal drive, speed bumps, circular yellow speed bumps, and three aggressive driving actions: sudden start, sudden stop, and sudden entry. The gathered data is processed and analyzed using a machine learning system designed for limited power and memory devices. The developed system resulted in 91.9% accuracy, 93.6% precision, and 92% recall. The achieved inference time on an Arduino Nano 33 BLE Sense with a 32-bit CPU running at 64 MHz is 34 ms and requires 2.6 kB peak RAM and 139.9 kB program flash memory, making it suitable for resource-constrained embedded systems.
Literature Review Basics and Understanding Reference Management.pptxDr Ramhari Poudyal
Three-day training on academic research focuses on analytical tools at United Technical College, supported by the University Grant Commission, Nepal. 24-26 May 2024
Understanding Inductive Bias in Machine LearningSUTEJAS
This presentation explores the concept of inductive bias in machine learning. It explains how algorithms come with built-in assumptions and preferences that guide the learning process. You'll learn about the different types of inductive bias and how they can impact the performance and generalizability of machine learning models.
The presentation also covers the positive and negative aspects of inductive bias, along with strategies for mitigating potential drawbacks. We'll explore examples of how bias manifests in algorithms like neural networks and decision trees.
By understanding inductive bias, you can gain valuable insights into how machine learning models work and make informed decisions when building and deploying them.
2. What we already know?
• Transmission fundamentals
– Time, frequency, phase etc.
• Antenna, Signal and signal propagation
– Transmission, interference and detection
ranges
• path loss
– Ground, sky and LOS
• Signal propagation effects
– Blocking/shadowing, reflection, scattering,
refraction, diffraction
– Delay spread and doppler effect
3. Today?
• Antenna and its types
• Antenna gain
• Propagation modes
– Ground wave, sky wave and LOS
• Attenuation
• Free space loss
• Noise and its types
4. Antenna
• Electrical conductor for conduction
electromagnetic energy
• Electric energy < -- > electromagnetic
energy
• Antenna characteristics are essentially the
same whether an antenna is sending or
receiving electromagnetic energy.
5. Radiation pattern
• A common way to characterize the
performance of an antenna
• Graphical representation of the radiation
properties of an antenna
• The simplest pattern is produced by an
idealized antenna known as isotropic
antenna (sphere with an antenna in
center)
7. Isotropic Antenna
• Isotropic Antenna is a point in space that
radiate power in all directions equally
• Its not a practical antenna just used as a
reference.
14. Antenna Gain
• Measure of directivity of an antenna
• Defined as power output in a particular direction,
compared to that produced in any direction by a
perfect radiator (isotropic)
• Its only possible on the expense of radiation in
other directions
• If an antenna has a gain of 3dB that means that
antenna improves upon isotropic antenna in that
direction by 3dB.
15. Antenna Gain
• Antenna gain is not related to more output
power but with directionality
• Effective area of an antenna is related to
that of the physical size of the antenna
and its shape
G = 4 х pi х Ae/lamda ^2
Ae is different from antenna to antenna
16. Propagation Modes
• A radiated signal from antenna travels
along one of three routes
– Ground wave
– Sky wave
– LOS
• We will only be concerned with LOS
17. Ground Wave Propagation
• More or less follow the earth curvature
• Propagate considerable distance well over the visual
horizon
• Frequency upto 2MHz
• One factor is that electromagnetic wave induces a
current in the earth’s surface (causes a bend towards the
earth)
• Another factor is diffraction
• Electromagnetic waves in this frequency range are
scattered in such a way that they don’t penetrate the
upper atmosphere.
• AM radio
20. Sky Wave Propagation
• Signal from the earth-based antenna is
reflected from the ionized layer of the
upper atmosphere back down to the earth
• Seems like reflection but actually
refraction.
• 2 – 30 MHz
• BBC , VoA
23. LOS Propagation
• Above 30MHz
• Not reflected by ionosphere (satellite
comm)
• For ground-based LOS communication
both Tx and Rx antennas must be within
effective LOS of each others
• Optical Vs Radio LOS
24. LOS Propagation
• Optical LOS
– d = 3.57 √h
– d= distance b/w antenna and horizon
– h= height of antenna in meters
• Effective / Radio LOS
– d=3.57√Kh
– K = adjustment factor to account for refraction,
typically K=4/3
• Max distance between two antennas
– 3.57 (√Kh1 + √Kh2)
– h1, h2 are height of antennas
25. LOS Transmission
• Signal received is not similar to signal
transmitted
• Significant impairments are
– Attenuation and attenuation distortion
– Free space loss
– Noise
– Atmospheric Absorption
– Multipath
– Refraction
26. Attenuation
• Strength of the signal falls with the
distance
• Expressed in decibels dB
• For unguided medium attenuation is a
complex function of distance and makeup
of the atmosphere
27. Attenuation
• Attenuation involves these factors
– Receive signal must be sufficiently strong to
be detected and interpreted
– Signal level must be sufficiently higher than
noise
– Attenuation is greater at higher frequencies,
causing distortion.
Amplifiers
Repeaters
can be used
Amplifiers that
amplify higher
frequency more
Than lower
frequency
28. Free Space Loss
• Signal disperses with distance
• Signal spreads larger over distances
• This type of attenuation is called free
space loss
• In ideal free space propagation
– Pr = Pt Gt Gr (lamda/4 х pi х d) 2
• For microwave systems
• Ls = 32.45 +20log d(km) + 20 log f (MHz)
29. Noise
• Unwanted signal created from the source
other than the transmitter
• Four categories
– Thermal noise
– Intermodulation noise
– Cross talk
– Impulsive noise
30. Noise
Thermal Noise
• Due to thermal agitation of electrons
• Always present and cannot be eliminated
• Uniformly distributed across the frequency spectrum
hence referred to as white noise
• Independent of frequency
• Thermal noise in watts present in a bandwidth of B Hertz
can be expressed as
N = kTB where k = boltzmann’s constt
1.38 х 10-23 J/K
T is Temp, in Kelvin
• Or in decibels-watt
– N = 10 log k + 10log T + 10 log B
31. Noise
Intermodulation Noise
• When signal with different frequencies
share the same medium, results in I.N.
• It produces signal at frequency that is the
sum, difference or multiple of two other
frequencies.
• E.g. f1 , f2 would result in f1+f2
32. Noise
Crosstalk
• Unwanted coupling between signal paths.
• The effect of one wire over the other in
twisted pair
• Can also occur when unwanted signals
are picked up by microwave antenna
33. Noise
Impulse Noise
• Irregular , continuous pulses
• Unpredictable therefore not possible to engineer
a transmission system to cope with it
• Generated from external electromagnetic
disturbance like lightning and faults and flaws in
the communication system
• A sharp spike of energy of 0.01 s duration can
destroy 560 bits of data being transmitted at
56kbps
34. Summary
• Signal and propagation
• Antenna types and propagation modes
• signal impairments
35. Assignment 2
• What are different signal propagation models for
indoor and outdoor environment?
• Okumura model, Hata model for urban areas
• What is multipath fading? What are the benefits?
• What is fresnal zone? What is its significance
w.r.t. obstacles ? (max 6 sentences)
• What are the different techniques that can be
used to use a shared medium among different
devices on a network?
• References should be added at the end.
Editor's Notes
A dipole antenna is the simplest type of radio antenna, consisting of a conductive wire rod that is half the length of the maximum wavelength the antenna is to generate. This wire rod is split in the middle, and the two sections are separated by an insulator.
A Yagi–Uda antenna, commonly known as a Yagi antenna, is a directional antenna consisting of multiple parallel elements in a line, usually half-wave dipoles made of metal rods. ... The reflector element is slightly longer than the driven dipole, whereas the directors are a little shorter.