Transmission line impedance

The short-circuit jumper is simulated by a 1 µΩ load impedance: Shorted transmission line. Transmission line v1 1 0 ac 1 sin rsource 1 2 75 t1 2 0 3 0 z0=75 td=1u rload 3 0 1u .ac lin 101 1m 1meg * Using “Nutmeg” program to plot analysis .end Resonances on shorted transmission line . At f=0 Hz: input: V=0, I=13.33 mA; end: V=0, I=13.33 mA.

Keep the stub section as short as possible and you can choose a transmission line impedance that works well for your layout (Zo=50 ohms is not a requirement). • Simple parallel termination: In a simple parallel termination scheme, the terminating resistor (Rl) is equal to the line impedance. Place the termination resistor …Question: A transmission line with impedance 0.08 + j0.25 ohm is used to deliver power to a load. The load is inductive and the load voltage is 220 0 Degree ...Using equation [1], we can solve for the length of the transmission line so that YA = -j*0.0038: Hence, if a short-circuited transmission line of length 0.22 wavelengths is added in parallel with the load, then the admittance will be entirely real and given by Yin=0.0192. Hence, the input impedance Zin = 1/Yin = 52 Ohms.Sep 12, 2022 · 3.7: Characteristic Impedance. Characteristic impedance is the ratio of voltage to current for a wave that is propagating in single direction on a transmission line. This is an important parameter in the analysis and design of circuits and systems using transmission lines. In this section, we formally define this parameter and derive an ... The job of an antenna is to convert the impedance seen by the EM wave, from the 50ohm or 75ohm characteristic impedance of the transmission line, to the 377ohm impedance of free space. The better the antenna is, the less of the wave that reaches it will be reflected back into the cable, and the more will propagate through free space. Most ...Transmission Line Impedance and Admittance 9. Power Transmission on Transmission Lines 10. Standing Wave and Standing Wave Ratio 11. Practical Transmission Lines 12. Problems 4 Chapter 1: Transmission Line Theory 1. Introduction Transmission line theory bridges the gap between field analysis and basic circuit theory and therefore is of …Transmission Lines 103 The above implies that3 I= r C L f +(z vt) (11.1.14) Consequently, V(z;t) I(z;t) = r L C = Z 0 (11.1.15) where Z 0 is the characteristic impedance of the transmission line. The above ratio is only true for one-way traveling wave, in this case, one that propagates in the +zdirection.

You can think of the characteristic impedance as the ratio between the voltage difference and current phasors if there was only an incident wave, and no reflected wave (so for example in an hypotetical infinite length transmission line or one with a reflection coefficient of 0): $$\frac{V(-l)}{I(-l)}=\frac{V_+e^{j\beta l}}{I_+e^{j\beta l}}=Z_0 ...There are more BitTorrent clients than we could possibly compare, but some of the most popular—and best—have been under the spotlight lately for sleazy ads and bad behavior. It’s time to check in on a few of our favorites to see how they fa...6.3.3 TE Mode. 6.3.4 Summary. This section derives the propagating EM fields for the parallel-plate waveguide shown in Figure 6.3.1. The parallel-plate waveguide shown in Figure 6.3.1 (a) has conducting planes at the top and bottom that (as an approximation) extend infinitely in the x direction.Open Line Impedance (I) The impedance at any point along the line takes on a simple form Zin(−ℓ) = v(−ℓ) i(−ℓ) = −jZ0 cot(βℓ) This is a special case of the more general transmission line equation with ZL= ∞. Note that the impedance is purely imaginary since an open lossless transmission line cannot dissipate any power. Line Impedance Measurement. For the determination of parameters for your single circuit line, you inject a test current into several different test loops. Each of the loops represents a possible fault scenario. Thereby, the measured loop impedances equal the loop impedances, which the connected protection device would determine during a real ...

If you're talking about the characteristic impedance of a transmission line, Z0, then no, length does not affect the quantity. All variables are independent of the length of the transmission line: Z0 = sqrt((R+jωL)/(G+jωC)) where: R is resistance per unit length; L is inductance per unit length; G is conductance per unit lengthCharacteristic Impedance: This is a crucial term in understanding transmission lines. It refers to the inherent resistance to current flow presented by an ...The above equation is important: it states that by using a quarter-wavelength of transmission line, the impedance of the load (ZA) can be transformed via the above equation. The utility of this operation can be seen via an example. Example. Match a load with impedance ZA=100 Ohms to be 50 Ohms using a quarter-wave transformer, as shown below.RF & Wireless. When RF engineers think about the impedance of their project’s transmission lines, they may automatically assume that these lines all have a nominal impedance of 50 ohms (Ω). That makes sense, as so much of today’s RF design work is based around that value. It’s not an arbitrary number; there are good technical reasons for ...Where Z c is complex frequency-dependent characteristic impedance and gamma is complex propagation constant ( is the attenuation constant (Np/m) and beta is the phase constant (rad/m) defined as Lambda is the wavelength in the transmission line — phase changes by over that length, see more in the Appendix). Those are the modal parameters in ...

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Apr 6, 2022 · RF & Wireless. When RF engineers think about the impedance of their project’s transmission lines, they may automatically assume that these lines all have a nominal impedance of 50 ohms (Ω). That makes sense, as so much of today’s RF design work is based around that value. It’s not an arbitrary number; there are good technical reasons for ... Transmission Line -Dr. Ray Kwok Common transmission lines most correct schematic twisted pair VLF lossy& noisy paralllel wire LF -HF noisy & lossy coaxial cable no distortion wide freq range microstrip (line) no distortion wide freq range lowest cost co-planar waveguide low cost flip chip access complex design waveguide lowest loss freq bands Z o lTRANSMISSION LINE PARAMETERS I n this chapter, we discuss the four basic transmission-line parameters: series resistance, series inductance. shunt capacitance, and shunt conductance. We also investigate transmission-line electric and magnetic fields. Series resistance accounts for ohmic ðI2RÞ line losses. Series impedance, Impedance Calculator. The Sierra Circuits Impedance Calculator uses the 2D numerical solution of Maxwell’s equations for PCB transmission lines. It renders fairly accurate results suitable for use in circuit board manufacturing and engineering analysis. In addition to the characteristic impedance of a transmission line, the tool also ... The impedance of transmission line is then readily calculated as the ratio of the voltage between the TLM terminals and the main mesh that includes the external voltage source. In simulations we used from 300 to 10000 slices ( ) where a slice represents elements as defined in the generalized topology of porous electrode shown in Fig. 2 .

Recapitulation. 2, located exactly λ/2 from the end of the slotted line. The position of z 2 is determined by the position of the appropriate minimum when the slotted line is terminated with a short circuit. With the slotted line terminated by the unknown impedance one looks for a voltage minimum located within λ/4 of the shorted position z …With the transmission line clearly defined as a circuit element, it can now be analyzed when a load is attached. We define the load to be located at z=0 to simplify the analysis. The current and voltage at the load can be related by the load impedence. Using equations 10 & 15, while setting z=0, we get.R ≈ l σ(δs2πa) (δs ≪ a) The impedance of a wire of length l and radius a ≫ δs is given by Equation 4.2.10. The resistance of such a wire is given by Equation 4.2.11. If, on the other hand, a < δs or merely ∼ δs, then current density is significant throughout the wire, including along the axis of the wire.Lecture -5 Standing waves on transmission line & impedance tr; Lecture -6 Loss less transmission line; Lecture -7 Impedance characteristics of loss less transmission; Lecture -8 Power transfer through a transmission line; Lecture -9 Graphical approach for transmission analysis; Lecture -10 Transmission line calculations using smith chart ...This section focuses on the frequency-dependent behavior introduced by obstacles and impedance transitions in transmission lines, including TEM lines, waveguides, and optical systems. Frequency-dependent transmission line behavior can also be introduced by loss, as discussed in Section 8.3.1, and by the frequency-dependent propagation velocity ...A Guide to Transmission Line Impedance | Advanced PCB Design Blog | Cadence Given the fact that there are 5 different transmission line impedance values, which one do you use for impedance matching? Here is what you need to know.The characteristic impedance (Z 0) of a transmission line is the resistance it would exhibit if it were infinite in length. This is entirely different from leakage resistance of the dielectric separating the two conductors, and the metallic resistance of the wires themselves.The short-circuit jumper is simulated by a 1 µΩ load impedance: Shorted transmission line. Transmission line v1 1 0 ac 1 sin rsource 1 2 75 t1 2 0 3 0 z0=75 td=1u rload 3 0 1u .ac lin 101 1m 1meg * Using “Nutmeg” program to plot analysis .end Resonances on shorted transmission line . At f=0 Hz: input: V=0, I=13.33 mA; end: V=0, I=13.33 mA.A transmission line’s termination impedance is intended to suppress signal reflection at an input to a component. Unfortunately, transmission lines can never be perfectly matched, and matching is limited by practical factors. Some components use on-die termination while others need to have it applied manually.Nov 10, 2020 · The value for a parallel termination is the characteristic impedance of the termination circuit or transmission line is terminated. Determining series terminating resistor values is not so straightforward. The series terminating resistor is intended to add up to the transmission line impedance when combined with the output impedance of the driver. The microstrip line is one of the most popular choices of transmission lines in microwave and RF circuits. They consist of a conductor fabricated on the dielectric substrate of permittivity ‘𝜀r’ with a grounded plane. The dielectric material and the air above the microstrip makes it a transmission line with the inhomogenous dielectric ...

an impedance model for each of the three sequence networks. For transmission and distribution lines, the positive and negative sequence impedances have the same values. The series impedance values in terms of the resistance and reactance values in Sections 1.6.2 and 1.6.3 are z1＝ra+1j⋅⎛⎝xa+xd ⎞⎠ positive sequence z2＝ra+1j⋅ ...

Given the fact that there are 5 different transmission line impedance values, which one do you use for impedance matching? Here is what you need to know. …The bottom line is the reduced surge impedance coupled with reduced thermal limits of underground lines results in an ac length limit that is difficult to overcome. Finding Length Limits The following figure shows a transmission line connecting two voltage buses with equal voltage amplitudes.In other words, a transmission line behaves like a resistor, at least for a moment. The amount of “resistance” presented by a transmission line is called its characteristic impedance, or surge impedance, symbolized in equations as \(Z_0\). Only after the pulse signal has had time to travel down the length of the transmission line and ...The impedance of the transmission line (a.k.a. trace) is 50 ohms, which means that as the signal travels down the cable it looks like a 50 ohm load to the driver. When it hits the end of the trace, it reflects back and causes parts of the trace to temporarily reach a much higher/lower voltage than it should. We call this overshoot and undershoot.This technique requires two measurements: the input impedance Zin Z i n when the transmission line is short-circuited and Zin Z i n when the transmission line is open-circuited. In Section 3.16, it is shown that the input impedance Zin Z i n of a short-circuited transmission line is. Z(SC) in = +jZ0 tan βl Z i n ( S C) = + j Z 0 tan β l.The term impedance was coined by Oliver Heaviside in July 1886. Heaviside recognised that the "resistance operator" (impedance) in his operational calculus was a complex number. ... The measurement of the impedance of devices and transmission lines is a practical problem in radio technology and other fields. Measurements of impedance may …Non-uniform impedance causes signal reflections and distortion. Therefore, at high frequencies, transmission lines need to have a controlled impedance to predict the behavior of the signals. It is crucial to pay attention to the transmission line effects in order to avoid signal reflections, crosstalk, and electromagnetic noise.Unfortunately for practice, such waves cannot propagate in every transmission line. To show this, let us have a look at the two last lines of Eqs. (100). For the TEM waves (Ez = 0, Hz = 0, kz = k), they are reduced to merely. ∇t × Et = 0, ∇t × Ht = 0, ∇t ⋅ Et = 0, ∇t ⋅ Ht = 0. Within the coarse-grain description of the conducting ...

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Input Impedance. When looking through the various transmission line impedance values, characteristic impedance and differential impedance generally stand out as the two important values as these are typically specified in signaling standards. However, there are really six transmission line impedance values that are important in PCB design.Jan 12, 2022 · The impedance value you calculate is the transmission line impedance the signal sees as it reflects off the mismatched load and travels on the line. In the limit of a very long transmission line (such as when the line length is many multiples of the wavelength), then the tanh function eventually converges to 1. ABCD parameters. To model a two-port network of transmission lines, we assume that the network is linear and bilateral. The type of network can be identified from ...Application: Impedance of Composite Line. A transmission line is made of two segments, each 1 m long (Figure 15.30). Calculate the input impedance of the combined line using a Smith chart if the speed of propagation on line (1) is 3 × 10 8 m/s and on line (2) 1 × 10 8 m/s. The lines operate at 300 MHz. Figure 15.30. 15.4. Application: …Line Impedance Measurement. For the determination of parameters for your single circuit line, you inject a test current into several different test loops. Each of the loops represents a possible fault scenario. Thereby, the measured loop impedances equal the loop impedances, which the connected protection device would determine during a real ...Figure 3A shows an example of a double conductor lossless transmission line. The wave impedance of the lossless transmission line is Z 0, the wave velocity is c, the total length of the line is l, the ideal voltage source u e s at the head end of the transmission line is a 100-V step signal with time delay, and the load end is connected with a ...Lossy Transmission Line Impedance Using the same methods to calculate the impedance for the low-loss line, we arrive at the following line voltage/current v(z) = v+e z(1+ˆ Le 2 z) = v+e z(1+ˆ L(z)) i(z) = v+ Z0 e z(1 ˆ L(z)) Where ˆL(z) is the complex reflection coefficient at position z and the load reflection coefficient is unaltered ...If you're talking about the characteristic impedance of a transmission line, Z0, then no, length does not affect the quantity. All variables are independent of the length of the transmission line: Z0 = sqrt((R+jωL)/(G+jωC)) where: R is resistance per unit length; L is inductance per unit length; G is conductance per unit lengthTransmission Line Impedance and Admittance 9. Power Transmission on Transmission Lines 10. Standing Wave and Standing Wave Ratio 11. Practical Transmission Lines 12. Problems 4 Chapter 1: Transmission Line Theory 1. Introduction Transmission line theory bridges the gap between field analysis and basic circuit theory and therefore is of … ….

Equation (2.17) gives the input impedance for a transmission line of length d, wave impedance Z o, space frequency β, terminated in load Z L. ... but go through a calibration procedure so the instrument knows the transmission line parameters, especially its electrical length. If you are using an instrument that doesn't do it for you, proceed ...Lossy Transmission Line Impedance Using the same methods to calculate the impedance for the low-loss line, we arrive at the following line voltage/current v(z) = v+e z(1+ˆ Le 2 z) = v+e z(1+ˆ L(z)) i(z) = v+ Z0 e z(1 ˆ L(z)) Where ˆL(z) is the complex reflection coefficient at position z and the load reflection coefficient is unaltered ...Coaxial Line Impedance Calculator. Dimensional units: mm mil. di (inner diameter) = do (outer diameter) = ur (relative magnetic permeability) = er (relative dielectric constant) = ... Capacitively Loaded Transmission Line Calculator. Dimensional units: mm inch. Zo (unloaded trace impedance, Ohms) = Tpd (unloaded propagation delay, ps/unit len ...Whenever there is a mismatch of impedance between transmission line and load, reflections will occur. If the incident signal is a continuous AC waveform, these reflections will mix with more of the oncoming incident waveform to produce stationary waveforms called standing waves.. The following illustration shows how a triangle-shaped incident …Transmission Line Impedance and Admittance 9. Power Transmission on Transmission Lines 10. Standing Wave and Standing Wave Ratio 11. Practical Transmission Lines 12. Problems 4 Chapter 1: Transmission Line Theory 1. Introduction Transmission line theory bridges the gap between field analysis and basic circuit theory and therefore is of …Using Transmission Lines A transmission line delivers an output signal at a distance from the point of signal input. Any two conductors can make up a transmission line. The signal which is transmitted from one end of the pair to the other end is the voltage between the conductors. Power transmission lines, telephone lines, and waveguides are ... This article offers an introduction to the Smith chart and how it’s used to make transmission-line calculations and fundamental impedance-matching circuits.PowerWorld Transmission Line Parameter Calculator v.1.0 Power Base: The system voltampere base in MVA. Voltage Base: The line-line voltage base in KV. Impedance Base: The impedance base in Ohms. This value is automatically computed when the power base and the voltage base are entered or modified. Admittance Base: The admittance base in Siemens. Characteristic impedance is the ratio of voltage to current for a wave that is propagating in single direction on a transmission line. This is an important parameter in the analysis and design of circuits and systems using transmission lines. In this section, we formally define this parameter and derive an expression for this parameter in terms ... Transmission line impedance, The impedance of a transmission line is not intended to restrict current flow in the way that an ordinary resistor would. Characteristic impedance is simply an unavoidable result of the interaction between a cable …, For a given short transmission line of impedance R+jX ohms/phase, the sending end and receiving end voltages Vs and Vr are fixed. Derive the expression for the maximum power that can be transmitted over the line. BUY. Power System Analysis and Design (MindTap Course List) 6th Edition. ISBN: 9781305632134., The characteristic impedance or surge impedance (usually written Z 0) of a uniform transmission line is the ratio of the amplitudes of voltage and current of a single wave propagating along the line; that is, a wave travelling in one direction in the absence of reflections in the other direction. , thus a big transmission line can have the same impedance as a small transmission line if one is scaled in proportion from the other. For most lines it is not practical to vary the ratios b a and D r much more than about 2.0/1 up to 10/1. Since the ln(2 1) ˇ0:69 and ln(10 1) ˇ2:3 the range of impedances, Transmission Lines 103 The above implies that3 I= r C L f +(z vt) (11.1.14) Consequently, V(z;t) I(z;t) = r L C = Z 0 (11.1.15) where Z 0 is the characteristic impedance of the transmission line. The above ratio is only true for one-way traveling wave, in this case, one that propagates in the +zdirection. , Transmission Lines 103 The above implies that3 I= r C L f +(z vt) (11.1.14) Consequently, V(z;t) I(z;t) = r L C = Z 0 (11.1.15) where Z 0 is the characteristic impedance of the transmission line. The above ratio is only true for one-way traveling wave, in this case, one that propagates in the +zdirection. , 4 Input Impedance of a Transmission Line The purpose of this section is to determine the input impedance of a transmission line; i.e., what amount of input current IINis needed to produce a given voltage VIN across the line as a function of the LRCG parameters in the transmission line, (see Figure 6 ). , With the transmission line clearly defined as a circuit element, it can now be analyzed when a load is attached. We define the load to be located at z=0 to simplify the analysis. The current and voltage at the load can be related by the load impedence. Using equations 10 & 15, while setting z=0, we get., Characteristic impedance is the ratio of voltage to current for a wave that is propagating in single direction on a transmission line. This is an important parameter in the analysis and design of circuits and systems using transmission lines. In this section, we formally define this parameter and derive an expression for this parameter in terms ..., Z BASE = Base Impedance. KV LL = Base Voltage (Kilo Volts Line-to-Line) MVA 3Ф = Base Power. A BASE = Base Amps. Z PU = Per Unit Impedance. Z PU GIVEN = Given Per Unit Impedance. Z = Impedance of circuit element (i.e. Capacitor, Reactor, Transformer, Cable, etc.) X C = Capacitor Bank Impedance (ohms) X C-PU = Capacitor Bank Per Unit Impedance., In general, θ = ( π / 2) ( f / f 0). The right-hand side of Equation (5.6.1) describes the series connection of short- and open-circuited stubs having characteristic impedances of Z 0 / 2 and half the original electrical length. This implies that the resulting transmission line resonators are one-quarter wavelength long at 2 f 0 (i.e., they ..., The Characteristic Impedance of a Transmission line is defined as the square root of ratio of series impedance per unit length per phase and shunt admittance per unit length per phase. If z and y are series impedance and shunt admittance of line. The transmission line of both short and medium-length use approximated lumped-parameter model. The …, Impedance matching in transmission lines is enforced to prevent reflections along an interconnect. Most impedance matching guidelines do not explicitly mention the input impedance of an interconnect, which will determine the S-parameters (specifically return loss)., A transmission line with a characteristic impedance of may be universally considered to have a characteristic admittance of where Y 0 = 1 Z 0 {\displaystyle Y_{0}={\frac {1}{Z_{0}}}\,} Any impedance, Z T {\displaystyle Z_{\text{T}}\,} expressed in ohms, may be normalised by dividing it by the characteristic impedance, so the normalised impedance using the …, 3.7: Characteristic Impedance. Characteristic impedance is the ratio of voltage to current for a wave that is propagating in single direction on a transmission line. This is an important parameter in the analysis and design of circuits and systems using transmission lines. In this section, we formally define this parameter and derive an ..., A parallel wire transmission line consists of wires separated by a dielectric spacer. Figure 7.1. 1 shows a common implementation, commonly known as “twin lead.”. The wires in twin lead line are held in place by a mechanical spacer comprised of the same low-loss dielectric material that forms the jacket of each wire., One of the most basic parameters of a transmission line is zo, its characteristic impedance. zo depends upon the geometry and the material of the transmission line. In this section, zo is calculated for four common transmission lines — coaxial, twin-lead, parallel plate, and microstrip. The cross-sections of these lines are shown in Figure 1 ..., Feb 7, 2022 · One of the main considerations when routing transmission lines is to control the impedance of the line by using a specific trace width for the line. If the impedance is not matched along the length of the line, it will create signal reflections and potentially disrupt the signal, leading to corruptions of the data being sent. , Equation 3.15.1 is the input impedance of a lossless transmission line having characteristic impedance Z0 and which is terminated into a load ZL. The result also depends on the length and phase propagation constant of the line. Note that Zin(l) is periodic in l. Since the argument of the complex exponential factors is 2βl, the frequency at ..., Kenneth L. Nist, KQ6QV has free software for calculating arbitrary transmission line impedance, as well as transmission line equations for Mathcad 11. atlc - Arbitrary Transmission Line Calculator (for transmission lines and directional couplers) by Dr. David Kirkby (G8WRB), who works at the department of Medical Physics, University College London., The impedance and admittance per unit length are frequency-dependent, in general, and are completely defined by transmission line type and cross-section and usually computed either with a static or quasi-static 2D field solver or …, istic impedance of the line: Z= V I (line impedance) (11.1.4) In addition to the impedance Z, a TEM line is characterized by its inductance per unit length L Cand its capacitance per unit length . For lossless lines, the three quantities Z,L,C are related as follows: L =μ Z η,C = η Z (inductance and capacitance per unit length) (11.1.5 ..., 3.1: Introduction to Transmission Lines Transmission lines are designed to support guided waves with controlled impedance, low loss, and a degree of immunity from EMI. 3.2: Types of Transmission Lines Two common types of transmission line are coaxial line and microstrip line. Both are examples of transverse electromagnetic (TEM) …, If you're talking about the characteristic impedance of a transmission line, Z0, then no, length does not affect the quantity. All variables are independent of the length of the transmission line: Z0 = sqrt((R+jωL)/(G+jωC)) where: R is resistance per unit length; L is inductance per unit length; G is conductance per unit length, The Transmission Line Table object is available for placement from the Place » Transmission Line Table command on the main menu, or from the Table objects drop-down menu on the Active Bar.After launching the Transmission Line Table placement command a new table object, populated with Layer and Impedance data is drawn from …, If you're talking about the characteristic impedance of a transmission line, Z0, then no, length does not affect the quantity. All variables are independent of the length of the transmission line: Z0 = sqrt((R+jωL)/(G+jωC)) where: R is resistance per unit length; L is inductance per unit length; G is conductance per unit length, 3.7: Characteristic Impedance. Characteristic impedance is the ratio of voltage to current for a wave that is propagating in single direction on a transmission line. This is an important parameter in the analysis and design of circuits and systems using transmission lines. In this section, we formally define this parameter and derive an ..., is known as the characteristic impedance of the transmission line. The solutions for the line voltage and line current given by (7.5) and (7.6), respec-tively, represent the superposition of and waves, that is, waves propagating in the positive z-andnegativez-directions,respectively. They are completely analogous, When we talk about S-parameters, impedance matching, transmission lines, and other fundamental concepts in RF/high-speed PCB design, the concept of 50 Ohm impedance comes up over and over. Look through signaling standards, component datasheets, application notes, and design guidelines on the internet; this is one …, Input Impedance. When looking through the various transmission line impedance values, characteristic impedance and differential impedance generally stand out as the two important values as these are typically specified in signaling standards. However, there are really six transmission line impedance values that are important in PCB design., Jun 29, 2021 · This article offers an introduction to the Smith chart and how it’s used to make transmission-line calculations and fundamental impedance-matching circuits. , The Electric Power Research Institute (EPRI) conducts research, development, and demonstration projects for the benefit of the public in the United States ..., thus a big transmission line can have the same impedance as a small transmission line if one is scaled in proportion from the other. For most lines it is not practical to vary the ratios b a and D r much more than about 2.0/1 up to 10/1. Since the ln(2 1) ˇ0:69 and ln(10 1) ˇ2:3 the range of impedances