.net barcode reader library Fundamentals of radio antennas in Software

Paint DataMatrix in Software Fundamentals of radio antennas

128 Fundamentals of radio antennas
DataMatrix Scanner In None
Using Barcode Control SDK for Software Control to generate, create, read, scan barcode image in Software applications.
DataMatrix Creation In None
Using Barcode creator for Software Control to generate, create DataMatrix image in Software applications.
H E F H E H
ECC200 Reader In None
Using Barcode decoder for Software Control to read, scan read, scan image in Software applications.
Painting Data Matrix In Visual C#
Using Barcode maker for VS .NET Control to generate, create ECC200 image in VS .NET applications.
Electric field intensity
Data Matrix ECC200 Creator In VS .NET
Using Barcode maker for ASP.NET Control to generate, create ECC200 image in ASP.NET applications.
Data Matrix Generator In .NET
Using Barcode maker for Visual Studio .NET Control to generate, create Data Matrix 2d barcode image in Visual Studio .NET applications.
Downward moving flux lines 0 Upward moving flux lines
Generating Data Matrix ECC200 In Visual Basic .NET
Using Barcode encoder for VS .NET Control to generate, create ECC200 image in VS .NET applications.
Barcode Creator In None
Using Barcode maker for Software Control to generate, create barcode image in Software applications.
Time H Clockwise flux lines 0 Counterclockwise flux lines 5-5 Electric and magnetic fields 90 out of phase
Generate EAN13 In None
Using Barcode creation for Software Control to generate, create UPC - 13 image in Software applications.
Data Matrix 2d Barcode Maker In None
Using Barcode generator for Software Control to generate, create DataMatrix image in Software applications.
waves is sent down the line, waves will be reflected in the same continual pattern The wave moving from the transmitter toward the end is called the incident wave, and its reflection is called the reflected wave A continuous flow of incident waves results in a continuous flow of reflected waves Because there is only one conductor, the two waves must pass each other Electrically, the only current that actually flows is the resultant of both of these waves The waves can reinforce or cancel each other as they move When they reinforce, the resultant wave is maximum; when they cancel, the resultant wave is minimum In a conductor that has a finite length, such as an antenna, the points at which the maxima and minima of the resultant wave occur (Fig 5-6C) are stationary In other words, the maximum and minimum points stand still, although both the incident and reflected waves are moving The resultant wave stands still on the line, only its amplitude being subject to change Because of this effect, the resultant is referred to as a standing wave The development of the standing wave on an antenna by actual addition of the traveling waves is illustrated in Fig 5-7 At the instant pictured in A, the incident and reflected waves just coincide The result is a standing wave having twice the amplitude of either traveling wave In B, the waves move apart in opposite directions, and
EAN 128 Generator In None
Using Barcode maker for Software Control to generate, create EAN 128 image in Software applications.
Make USS Code 39 In None
Using Barcode encoder for Software Control to generate, create ANSI/AIM Code 39 image in Software applications.
Magnetic field intensity
EAN / UCC - 8 Generator In None
Using Barcode creator for Software Control to generate, create GS1 - 8 image in Software applications.
Draw Linear In C#.NET
Using Barcode creator for VS .NET Control to generate, create Linear image in .NET applications.
Antenna fundamentals 129
Recognizing Data Matrix ECC200 In Java
Using Barcode scanner for Java Control to read, scan read, scan image in Java applications.
Painting Code-39 In Java
Using Barcode encoder for Java Control to generate, create Code 39 Full ASCII image in Java applications.
Incident wave
Paint 1D In .NET Framework
Using Barcode encoder for VS .NET Control to generate, create Linear Barcode image in .NET applications.
Barcode Maker In VS .NET
Using Barcode generation for Reporting Service Control to generate, create bar code image in Reporting Service applications.
Reflected wave
Generating Barcode In VB.NET
Using Barcode printer for Visual Studio .NET Control to generate, create barcode image in .NET applications.
Bar Code Printer In Java
Using Barcode drawer for Android Control to generate, create bar code image in Android applications.
5-6 Traveling waves on an antenna and a typical resultant wave
the amplitude of the resultant decreases, but the points of maximum and minimum do not move When the traveling waves have moved to a position of 180 phase difference, the resultant is zero along the entire length of the antenna, as shown in C At this instant, there can be no current flow in the antenna The continuing movement of the traveling waves, shown in D, builds up a resultant in a direction opposite to that in A The in-phase condition of the traveling waves results in a standing wave, in E, equal in amplitude, but 180 out of phase with the standing wave in A If the progressive pictures of the standing wave are assembled on one set of axes, the result is as in Fig 5-8 The net effect of the incident and reflected waves is apparent The curves are lettered with reference to Fig 5-7 As the traveling waves move past each other, the standing wave changes only its amplitude The fixed minimum points are called nodes, and the curves representing the amplitude are called loops The concept of the standing wave can be applied to the half-wave antenna with reference to either current or voltage distribution at any instant This application is possible because there are traveling waves of both voltage and current Because voltage and current are out of phase on the half-wave antenna, the standing waves also are found to be out of phase
130 Fundamentals of radio antennas
Resultant
Resultant
Resultant
Resultant
Resultant
5-7 Development of standing wave from traveling wave
Antenna fundamentals 131
Loops A
Node 5-8 Standing waves B
C Node D Loops E
Voltage and current distribution on half-wave antenna
When an RF transmitter is feeding a half-wave antenna, positive and negative charges move back and forth along the antenna (Figs 5-9 and 5-10) The first picture shows the position of the charges at some arbitrary time, T0 The RF charges being observed are at the ends of the antenna, and there is a maximum difference in potential between the ends, A and B The remaining illustrations show the instantaneous positions of the charges at regular intervals of 225 throughout a complete cycle To the right of each instantaneous position of the charges are curves representing the current and voltage at that particular time for any point on the antenna For example, at time T0, the positive and negative charges are at points A and B on the antenna The voltage between these points represents a maximum difference of potential The current, being 90 out of phase in respect to the voltage, is everywhere zero These distribution curves are standing waves derived in the same manner as those covered in the previous paragraph The next illustration shows the position of the charges at time T1 The standing wave of current is a relative maximum at the center of the antenna This current loop has nodes that remain at the ends of the antenna, and it is, therefore, 90 out of phase with the standing wave of voltage At T2 and T3, the charges move closer together, and the standing wave of voltage slowly decreases in amplitude Conversely, the current loop increases in magnitude When the charges meet after 90 of the RF cycle (T4), the effect is that of having the positive and negative charges cancel The voltage loop accordingly is zero everywhere on the antenna, and the current loop rises to its maximum value, unimpeded by any charge on the antenna At time T5, the charges have passed each other, each charge having moved past the center point of the antenna The polarity of the voltage loops is reversed, and they build up in the opposite direction, keeping the node always at the center point of the antenna The reversal of polarity is shown in the charge positions at T3, T4, and
Copyright © OnBarcode.com . All rights reserved.