03-04-2016, 11:44 AM
I want to know. In detail about parameters of antenna in ppt format
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basic antenna theory ppt
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I want to know. In detail about parameters of antenna in ppt format
08-04-2016, 09:15 AM
basic antenna theory ppt
Antenna theory and antenna terminology can seem complicated to the uninitiated. A lot goes into designing antennas but with a little bit of guidance and explanation, antenna users (network designers, systems integrators, end users) can read through the antenna specifications and choose the right antenna style for their wireless network design.
In this paper we will go over some simple techniques to help you better understand some terminologyused and how it is applied in the Antenna industry. This will be part one of a two part series white paper. Part two will cover more advanced details. Both parts will provide the reader a wealth of knowledge that is essential for antenna selection and solutions.
So let’s get started. The Antenna Radiation Pattern is a graphical representation of the antennas radiated electrical performance. This wave of energy (electromagnetic in origin) emitted from the antenna that propagates through space is measured at a defined Angle, Amplitude, and Frequency. The measurement of this performance is commonly presented in a graphical format.
Let’s look at an Omni-directional antenna example: Think of the ripple that is created when a person throws a stone in the middle of a calm body of water (such as a pond). As the rock enters the water it causes the water all around it to rise and creates a ripple in the water.
• Think of this ripple as the “WAVE”.
• Think of the “FREQUENCY” as the number of the waves or the occurrences where the wave repeats over a period of time (from the stone to the shore).
• Think of the size in height of the wave as the “AMPLITUDE”, and
• Think of the length of the wave as the “WAVELENGTH”.
• As this wave moves outward away from the rock’s point of entry and towards the shore, the migration of this wave is called “PROPAGATION”.
Think of the letter “S” turned sideways to get a visual image of the peaks and valleys of the propagation wave. If this wave were to get smaller or squeezed and the “amount of occurrences increased” that would indicate that the frequency is getting higher. If this wave were to be stretched out longer and the “amount of occurrences decreased” then we can relate to the frequency becoming lower.
Antenna Fundamentals
Let's get right down to the study of antennas and Antenna Basics. Suppose one day you're walking down the street and a kind but impatient person runs up and asks you to design an antenna for them. "Sure", you quickly reply, adding "what is the desired frequency, gain, bandwidth, impedance, and polarization?"
Or perhaps you have never heard of (or are a little rusty) on the above parameters. Well then, you've come to the right place. Before we can design an antenna or discuss antenna types, we must understand the basics of antennas, which are the fundamental parameters that characterize an antenna.
So let us learn something. We'll start with frequency and step through radiation patterns, directivity and gain, and ultimately close with an explanation on why antennas radiate. Jump ahead if this is already familiar to you.
Frequency
The basics of sinusoids (sine and cosine waves), wavelength, frequency and the speed of light.
More Advanced Frequency Information
A discussion on how all waveforms in the universe are made up of the sum of sinusoids (simple waves) This helps explains why in antenna theory we always discuss wavelength and frequency no matter what signal (information) we want to transmit.
Frequency Bands
No discussion on antenna fundamentals is complete without a real-world list of frequency bands.
Radiation Pattern
The radiation pattern for an antenna is defined on this page. We have 3D graphs of real antenna radiation patterns, with a discussion on isotropic, omnidirectional and directional radiation patterns. Radiation patterns are of the utmost importance in the discussion of antenna basics.
Field Regions
The introduction to antennas continues with a discussion of Field Regions. The Far Field, Near Field and Fresnel Regions for an antenna is presented.
Directivity
Directivity is fundamental to antennas. It is a measure of how "directional" an antenna's radiation pattern is.
Antenna Efficiency
An antenna's efficiency is a measure of how much power is radiated by the antenna relative to the antenna input power.
Antenna Gain
Antenna Gain is a measure of power radiated in a particular direction (typically the peak direction of radiation).
Beamwidths and Sidelobes
An antenna's radiation pattern in the far field is often characterized by it's beamwidth and sidelobe levels. This introduction to antenas illustrates this with an example.
Impedance
Antenna Impedance is presented as the ratio of voltage to current at the antenna's terminals. Low- and High-Frequency models are presented for transmission lines. The fundamentals of antenna theory requires that the antenna be "impedance matched" to the transmission line or the antenna will not radiate. The concept of VSWR is introduced as a measure of how well matched an antenna is.
Bandwidth
The bandwidth of an antenna is the frequency range over which the antenna radiates. The bandwidth can be defined in different ways; this page presents an introduction to antenna bandwidth.
Polarization of Waves
All electromagnetic plane waves have an associated polarization. The antenna concepts of Linear, Circular and elliptical polarization are presented.
Polarization of Antennas
Antennas are also classified by their polarization; this defines the type of plane wave polarization the antenna is most sensitive to. This is a fundamental antenna concept.
Effective Aperture
Effective aperture is a basic antenna concept that is a measure of the power captured by an antenna from a plane wave. Effective aperture can be expressed as a function of the antenna gain and the wavelength of interest.
Friis Transmission Equation
Friis Transmission Formula is the most fundamental equation of antenna theory. This equation relates transmit power, antenna gains, distance and wavelength to received power. This page is a must-read for those interested in antenna theory.
Antenna Temperature
Antenna Temperature is a property of an antenna and the environment it operates in. It is a measure of the noise received by the antenna due to thermal (or temperature) effects.
Why do Antennas Radiate?
The antenna basics section concludes with a discussion of Why Antennas Radiate. The idea here is to explain the physical concepts that produce radiation in terms of electrons flowing on a wire.
Antenna theory and antenna terminology can seem complicated to the uninitiated. A lot goes into designing antennas but with a little bit of guidance and explanation, antenna users (network designers, systems integrators, end users) can read through the antenna specifications and choose the right antenna style for their wireless network design.
In this paper we will go over some simple techniques to help you better understand some terminologyused and how it is applied in the Antenna industry. This will be part one of a two part series white paper. Part two will cover more advanced details. Both parts will provide the reader a wealth of knowledge that is essential for antenna selection and solutions.
So let’s get started. The Antenna Radiation Pattern is a graphical representation of the antennas radiated electrical performance. This wave of energy (electromagnetic in origin) emitted from the antenna that propagates through space is measured at a defined Angle, Amplitude, and Frequency. The measurement of this performance is commonly presented in a graphical format.
Let’s look at an Omni-directional antenna example: Think of the ripple that is created when a person throws a stone in the middle of a calm body of water (such as a pond). As the rock enters the water it causes the water all around it to rise and creates a ripple in the water.
• Think of this ripple as the “WAVE”.
• Think of the “FREQUENCY” as the number of the waves or the occurrences where the wave repeats over a period of time (from the stone to the shore).
• Think of the size in height of the wave as the “AMPLITUDE”, and
• Think of the length of the wave as the “WAVELENGTH”.
• As this wave moves outward away from the rock’s point of entry and towards the shore, the migration of this wave is called “PROPAGATION”.
Think of the letter “S” turned sideways to get a visual image of the peaks and valleys of the propagation wave. If this wave were to get smaller or squeezed and the “amount of occurrences increased” that would indicate that the frequency is getting higher. If this wave were to be stretched out longer and the “amount of occurrences decreased” then we can relate to the frequency becoming lower.
Antenna Fundamentals
Let's get right down to the study of antennas and Antenna Basics. Suppose one day you're walking down the street and a kind but impatient person runs up and asks you to design an antenna for them. "Sure", you quickly reply, adding "what is the desired frequency, gain, bandwidth, impedance, and polarization?"
Or perhaps you have never heard of (or are a little rusty) on the above parameters. Well then, you've come to the right place. Before we can design an antenna or discuss antenna types, we must understand the basics of antennas, which are the fundamental parameters that characterize an antenna.
So let us learn something. We'll start with frequency and step through radiation patterns, directivity and gain, and ultimately close with an explanation on why antennas radiate. Jump ahead if this is already familiar to you.
Frequency
The basics of sinusoids (sine and cosine waves), wavelength, frequency and the speed of light.
More Advanced Frequency Information
A discussion on how all waveforms in the universe are made up of the sum of sinusoids (simple waves) This helps explains why in antenna theory we always discuss wavelength and frequency no matter what signal (information) we want to transmit.
Frequency Bands
No discussion on antenna fundamentals is complete without a real-world list of frequency bands.
Radiation Pattern
The radiation pattern for an antenna is defined on this page. We have 3D graphs of real antenna radiation patterns, with a discussion on isotropic, omnidirectional and directional radiation patterns. Radiation patterns are of the utmost importance in the discussion of antenna basics.
Field Regions
The introduction to antennas continues with a discussion of Field Regions. The Far Field, Near Field and Fresnel Regions for an antenna is presented.
Directivity
Directivity is fundamental to antennas. It is a measure of how "directional" an antenna's radiation pattern is.
Antenna Efficiency
An antenna's efficiency is a measure of how much power is radiated by the antenna relative to the antenna input power.
Antenna Gain
Antenna Gain is a measure of power radiated in a particular direction (typically the peak direction of radiation).
Beamwidths and Sidelobes
An antenna's radiation pattern in the far field is often characterized by it's beamwidth and sidelobe levels. This introduction to antenas illustrates this with an example.
Impedance
Antenna Impedance is presented as the ratio of voltage to current at the antenna's terminals. Low- and High-Frequency models are presented for transmission lines. The fundamentals of antenna theory requires that the antenna be "impedance matched" to the transmission line or the antenna will not radiate. The concept of VSWR is introduced as a measure of how well matched an antenna is.
Bandwidth
The bandwidth of an antenna is the frequency range over which the antenna radiates. The bandwidth can be defined in different ways; this page presents an introduction to antenna bandwidth.
Polarization of Waves
All electromagnetic plane waves have an associated polarization. The antenna concepts of Linear, Circular and elliptical polarization are presented.
Polarization of Antennas
Antennas are also classified by their polarization; this defines the type of plane wave polarization the antenna is most sensitive to. This is a fundamental antenna concept.
Effective Aperture
Effective aperture is a basic antenna concept that is a measure of the power captured by an antenna from a plane wave. Effective aperture can be expressed as a function of the antenna gain and the wavelength of interest.
Friis Transmission Equation
Friis Transmission Formula is the most fundamental equation of antenna theory. This equation relates transmit power, antenna gains, distance and wavelength to received power. This page is a must-read for those interested in antenna theory.
Antenna Temperature
Antenna Temperature is a property of an antenna and the environment it operates in. It is a measure of the noise received by the antenna due to thermal (or temperature) effects.
Why do Antennas Radiate?
The antenna basics section concludes with a discussion of Why Antennas Radiate. The idea here is to explain the physical concepts that produce radiation in terms of electrons flowing on a wire.
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