 Home
 Products
 Integration
 Tutorial
 Barcode FAQ
 Purchase
 Company
.net barcode reader library Stripline in Software
Stripline Decoding Data Matrix ECC200 In None Using Barcode Control SDK for Software Control to generate, create, read, scan barcode image in Software applications. Encode DataMatrix In None Using Barcode generator for Software Control to generate, create DataMatrix image in Software applications. Dielectric 31M Stripline transmission line
Decoding Data Matrix 2d Barcode In None Using Barcode scanner for Software Control to read, scan read, scan image in Software applications. Data Matrix Maker In C# Using Barcode encoder for Visual Studio .NET Control to generate, create ECC200 image in .NET framework applications. Groundplane
Make Data Matrix ECC200 In .NET Using Barcode encoder for ASP.NET Control to generate, create DataMatrix image in ASP.NET applications. Create DataMatrix In .NET Using Barcode creation for Visual Studio .NET Control to generate, create Data Matrix 2d barcode image in .NET framework applications. R If X >> R Then: ZO = L/C L
DataMatrix Creator In VB.NET Using Barcode maker for .NET framework Control to generate, create Data Matrix 2d barcode image in Visual Studio .NET applications. Code 39 Extended Encoder In None Using Barcode creator for Software Control to generate, create Code 39 image in Software applications. 32 Equivalent circuit of transmission line
UPCA Supplement 2 Generation In None Using Barcode creation for Software Control to generate, create Universal Product Code version A image in Software applications. Barcode Encoder In None Using Barcode maker for Software Control to generate, create bar code image in Software applications. Transmission line characteristic impedance (Zo) 65 In microwave systems the resistances are typically very low compared with the reactances, so Eq 31 can be reduced to the simplified form: Zo = L C [32] Barcode Creator In None Using Barcode creator for Software Control to generate, create bar code image in Software applications. Encoding EAN 13 In None Using Barcode creator for Software Control to generate, create GTIN  13 image in Software applications. Example 31 A nearly lossless transmission line (R is very small) has a unit length inductance of 375 nH and a unit length capacitance of 15 pF Find the characteristic impedance Zo Solution: Zo = L C 1H 109 nH Identcode Generator In None Using Barcode maker for Software Control to generate, create Identcode image in Software applications. Code 128B Generation In C# Using Barcode maker for .NET framework Control to generate, create Code 128B image in Visual Studio .NET applications. 375 nH 15 pF
Encode Barcode In Java Using Barcode generation for Android Control to generate, create bar code image in Android applications. Decoding Code128 In VB.NET Using Barcode decoder for .NET Control to read, scan read, scan image in .NET framework applications. 1F 1012 pF
Code 128 Code Set B Creation In Java Using Barcode generation for Java Control to generate, create ANSI/AIM Code 128 image in Java applications. EAN13 Drawer In Visual Basic .NET Using Barcode creation for .NET Control to generate, create EAN / UCC  13 image in .NET framework applications. 375 10 9 H 15 10 12 F 25 103 = 50
Recognize UPC Code In None Using Barcode decoder for Software Control to read, scan read, scan image in Software applications. Painting USS128 In ObjectiveC Using Barcode creator for iPad Control to generate, create USS128 image in iPad applications. The characteristic impedance for a specific type of line is a function of the conductor size, the conductor spacing, the conductor geometry (see again Fig 31), and the dielectric constant of the insulating material used between the conductors The dielectric constant e is equal to the reciprocal of the velocity (squared) of the wave when a specific medium is used: e= 1 v2 [33] where e is the dielectric constant (for a perfect vacuum e = 1000) v is the velocity of the wave in the medium (a) Parallel line Zo = 276 2S log d e [34] 66 Transmission lines where Zo is the characteristic impedance, in ohms e is the dielectric constant S is the centertocenter spacing of the conductors d is the diameter of the conductors (b) Coaxial line Zo = where D is the diameter of the outer conductor d is the diameter of the inner conductor (c) Shielded parallel line Zo = where A = s/d B = s/D (d) Stripline Zo = where et is the relative dielectric constant of the printed wiring board (PWB) T is the thickness of the printed wiring board W is the width of the stripline conductor The relative dielectric constant et used above differs from the normal dielectric constant of the material used in the PWB The relative and normal dielectric constants move closer together for larger values of the ratio W/T Example 32 A stripline transmission line is built on a 4mmthick printed wiring board that has a relative dielectric constant of 55 Calculate the characteristic impedance if the width of the strip is 2 mm Solution: Zo = 377 et T W 377 et T W [37A] (1 B2) 276 log 2A (1 + B2) e [36] 138 D log d e [35] Transmission line characteristics 67
377 55 4 mm 2 mm
377 (2) = 321 235 In practical situations, we usually don t need to calculate the characteristic impedance of a stripline, but rather design the line to fit a specific system impedance (eg, 50 ) We can make some choices of printed circuit material (hence dielectric constant) and thickness, but even these are usually limited in practice by the availability of standardized boards Thus, stripline width is the variable parameter Equation 32 can be arranged to the form: W= 377 T Zo e [37B] The impedance of 50 is accepted as standard for RF systems, except in the cable TV industry The reason for this diversity is that power handling ability and low loss operation don t occur at the same characteristic impedance For example, the maximum power handling ability for coaxial cables occurs at 30 , while the lowest loss occurs at 77 ; 50 is therefore a reasonable tradeoff between the two points In the cable TV industry, however, the RF power levels are minuscule, but lines are long The tradeoff for TV is to use 75 as the standard system impedance in order to take advantage of the reduced attenuation factor Transmission line characteristics
Velocity factor
In the section preceding this section, we discovered that the velocity of the wave (or signal) in the transmission line is less than the freespace velocity (ie, less than the speed of light) Further, we discovered in Eq 33 that velocity is related to the dielectric constant of the insulating material that separates the conductors in the transmission line Velocity factor v is usually specified as a decimal fraction of c, the speed of light (3 108 m/s) For example, if the velocity factor of a transmission line is rated at 066, then the velocity of the wave is 066c, or (066) (3 108 m/s) = 198 108 m/s Velocity factor becomes important when designing things like transmission line transformers, or any other device in which the length of the line is important In most cases, the transmission line length is specified in terms of electrical length, which can be either an angular measurement (eg, 180 or radians), or a relative measure keyed to wavelength (eg, onehalf wavelength, which is the same as 180 ) The physical length of the line is longer than the equivalent electrical length For example, let s consider a 1GHz halfwavelength transmission line A rule of thumb tells us that the length of a wave (in meters) in free space is 030/F, where frequency F is expressed in gigahertz; therefore, a halfwavelength line is 015/F 68 Transmission lines At 1 GHz, the line must be 015 m/1 GHz = 015 m If the velocity factor is 080, then the physical length of the transmission line that will achieve the desired electrical length is [(015 m) (v)]/F = [(015 m) (080)]/1 GHz = 012 m The derivation of the rule of thumb is left as an exercise for the student (Hint: It comes from the relationship between wavelength, frequency, and velocity of propagation for any form of wave) There are certain practical considerations regarding velocity factor that result from the fact that the physical and electrical lengths are not equal For example, in a certain type of phasedarray antenna design, radiating elements are spaced a halfwavelength apart, and must be fed 180 (halfwave) out of phase with each other The simplest interconnect is to use a halfwave transmission line between the 0 element and the 180 element According to the standard wisdom, the transmission line will create the 180 phase delay required for the correct operation of the antenna Unfortunately, because of the velocity factor, the physical length for a onehalf electrical wavelength cable is shorter than the freespace halfwave distance between elements In other words, the cable will be too short to reach between the radiating elements by the amount of the velocity factor! Clearly, velocity factor is a topic that must be understood before transmission lines can be used in practical situations Table 31 shows the velocity factors for several types of popular transmission line Because these are nominal values, the actual velocity factor for any given line should be measured

