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barcode in vb.net 2005 Transmissionline types in Software
Transmissionline types QR Code Reader In None Using Barcode Control SDK for Software Control to generate, create, read, scan barcode image in Software applications. Printing QRCode In None Using Barcode encoder for Software Control to generate, create QR Code image in Software applications. As you recall, any transmission line has a characteristic impedance, or Zo, that depends on the line construction. This property is sometimes used to make impedance transformers out of coaxial or parallelwire line. Transmissionline transformers are always made from quarterwave sections. From the previous chapter, remember the formula for the length of a quarterwave section, that is, QR Code JIS X 0510 Decoder In None Using Barcode reader for Software Control to read, scan read, scan image in Software applications. QR Code ISO/IEC18004 Maker In Visual C# Using Barcode printer for .NET Control to generate, create QRCode image in .NET framework applications. where Lft is the length of the section in feet, v is the velocity factor expressed as a fraction, and fo is the frequency of operation in megahertz. If the length Lm is in meters, then: Lm 75v/fo Denso QR Bar Code Generator In .NET Using Barcode drawer for ASP.NET Control to generate, create QR image in ASP.NET applications. Make QR In VS .NET Using Barcode creation for .NET framework Control to generate, create QR Code 2d barcode image in Visual Studio .NET applications. In the last chapter, you saw how a short circuit is changed into an open circuit, and vice versa, by a quarterwave section of line. What happens to a pure resistive impedance at one end of such a line What will be seen at the opposite end Let a quarterwave section of line, with characteristic impedance Zo, be terminated in a purely resistive impedance Rout. Then the input impedance is also a pure resistance Rin , and the following relationship holds: Zo2 RinRout Paint QR Code ISO/IEC18004 In Visual Basic .NET Using Barcode generator for Visual Studio .NET Control to generate, create QR Code image in VS .NET applications. UCC  12 Creation In None Using Barcode maker for Software Control to generate, create GTIN  12 image in Software applications. This is illustrated in Fig. 1811. This formula can be broken down to solve for Rin in terms of Rout , or vice versa: Rin and Rout Zo2/Rin. Zo2/Rout Paint GTIN  13 In None Using Barcode generator for Software Control to generate, create EAN 13 image in Software applications. Barcode Maker In None Using Barcode drawer for Software Control to generate, create barcode image in Software applications. These relationships hold at the frequency, fo, for which the line is 1/4 wavelength long. Neglecting line losses, these relationships will also hold at the odd harmonics of fo, that is, at 3fo, 5fo, 7fo, and so on. At other frequencies, the line will not act as a transformer, but instead, will behave in complicated ways that are beyond the scope of this discussion. Quarterwave transformers are most often used in antenna systems, especially at the higher frequencies, where their dimensions become practical. Bar Code Drawer In None Using Barcode drawer for Software Control to generate, create barcode image in Software applications. ANSI/AIM Code 128 Printer In None Using Barcode generation for Software Control to generate, create Code 128C image in Software applications. Problem 185 GTIN  8 Generator In None Using Barcode generator for Software Control to generate, create EAN 8 image in Software applications. Linear Drawer In .NET Framework Using Barcode maker for Visual Studio .NET Control to generate, create Linear 1D Barcode image in VS .NET applications. An antenna has a purely resistive impedance of 100 . It is connected to a 1/4wave section of 75 coaxial cable. What will be the impedance at the input end of the section Use the formula from above: Painting Matrix Barcode In .NET Using Barcode creator for ASP.NET Control to generate, create 2D Barcode image in ASP.NET applications. Read Barcode In Java Using Barcode recognizer for Java Control to read, scan read, scan image in Java applications. AM FL Y
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What about reactance 341
1811 A quarterwave matching section of transmission line. Abbreviations are discussed in the text.
Zo2/Rout 752/100 56 5625/100 Problem 186 An antenna is known to have a pure resistance of 600 . You want to match it to 50.0 pure resistance. What is the characteristic impedance needed for a quarterwave matching section Use this formula: Zo2 Zo2 Zo2 RinRout 600 50 30,000 (30,000)1/2 173 The challenge is to find a line that has this particular Zo. Commercially manufactured lines come in standard Zo values, and a perfect match might not be obtainable. In that case, the closest obtainable Zo should be used. In this case, it would probably be 150 . If nothing is available anywhere near the characteristic impedance needed for a quarterwave matching section, then a coiltype transformer will probably have to be used instead. A quarterwave matching section should be made using unbalanced line if the load is unbalanced and balanced line if the load is balanced. The major disadvantage of quarterwave sections is that they work only at specific frequencies. But this is often offset by the ease with which they are constructed, if radio equipment is to be used at only one frequency, or at oddharmonic frequencies. What about reactance
Things are simple when there is no reactance in an ac circuit using transformers. But often, especially in radiofrequency circuits, pure resistance doesn t occur naturally. It has to be obtained by using inductors and/or capacitors to cancel the reactance out. 342 Transformers and impedance matching Reactance makes a perfect match impossible, no matter what the turns ratio or Zo of the transformer. A small amount of reactance can be tolerated at lower radio frequencies (below about 30 MHz). A nearperfect match becomes more important at higher frequencies. The behavior of reactance, as it is coupled through transformer windings, is too complicated for a thorough analysis here. But if you re interested in delving into it, there are plenty of good engineering texts that deal with it in all its mathematical glory. Recall that inductive and capacitive reactances are opposite in effect, and that their magnitudes can vary. If a load presents a complex impedance R + jX, with X not equal to zero, it is always possible to cancel out the reactance X by adding an equal and opposite reactance ( X) in the circuit. This can be done by connecting an inductor or capacitor in series with the load. For radio communications over a wide band, adjustable impedancematching and reactancecanceling networks can be placed between a transmitter and an antenna system. Such a device is called a transmatch and is popular among radio hams, who use frequencies ranging from 1.8 MHz to the microwave spectrum.

