Terminate the transmission line in its characteristic impedance when the one-way propagation delay of the PCB track is equal to or greater than one-half the applied signal rise/fall time (whichever edge is faster). The development of the expressions for L and R is more involved, as there will be current in the interior of the inner conductor. 2. Cadence/AWR. 2. Calculates the. At a distance x into the line, there is current phasor I(x) traveling through each wire, and there is a voltage difference phasor V(x) between the wires (bottom voltage minus top voltage). This type of transmission line is frequently encountered as a feed line on antenna booms, especially with log-periodic dipole arrays. In general, a line impedance of a lossy transmission line is a frequency dependent. Since the argument of the complex exponential factors is 2βl, the frequency. 4. Effective Dielectric Constant ( εeff ):2. Hopefully, you can see how this inductive reasoning continues indefinitely. 19. Suppose that Zg=50 Ohms, ZA=50 Ohms, Z0=200 Ohm, and that the line is a quarterwavelength long. Use our free online app Characteristic Impedance of a Transmission Line Calculator to determine all important calculations with parameters and constants. Microstrip Characteristic Impedance Calculator Using a Formula by Brian C Wadell Used for calculating the Zo of PCB transmission lines, showing the formula used. The equations that are used to calculate stripline impedance are simple, but there is a large number of terms, which includes a. The user will select the circuit materials and the circuit construction, after which the software will determine the predicted impedance and other electrical information. Note. This will also provide the time delay the cable provides for a signal and also the capacitance and inductance per. Distance relays require knowledge of the positive-sequence (Z 1L) and zero-sequence (Z 0L) impedances of the line. Z0 = Impedance of the transmission line is about ≈√L/C. Clemson Vehicular Electronics Laboratory: Transmission Line Impedance Calculator. The input impedance is the ratio of input voltage to the input current and is given by equation 3. In general, θ = ( π / 2) ( f / f 0). The Coaxial Line Impedance (Z0) Calculator is a valuable tool for engineers working with RF and telecommunications systems. This calculator provides accurate microstrip transmission line analysis and synthesis. 6. 1. The nice part about coax is that it can be bent and flexible unlike most pcb transmission lines. Call us: +1 (800) 763-7503 Email us: through our Customer Care form. R source +R series termination resistor = Transmission line impedance (Z 0). This calculator is a tool for designing balanced transmission lines with a specific desired characteristic impedance 𝑍c Z c and made of parallel square stock conductors of a given side length 𝑑 d. Calculation parameters: The conducting wire of circuit and material the inductor is made from, are both uniform and they have the same thickness everywhere; the source supplies AC current. THESE FORMULAS ARE APPROXIMATIONS! They should not be used when a high degree of accuracy is required. Type in a Radius and Spacing and press "Calculate". For more information see About. The input impedance of a short- or open-circuited lossless transmission line is completely imaginary-valued and is given by Equations 3. Satellite Look Angle Calculator. The calculator provides the impedance, time delay, inductance and capacitance of the cable in ohms,. A twisted-pair cable is simply two wires that are twisted together so as to reduce radiated EMI (electromagnetic interference) and mitigate the effects of received EMI. G = 2πσ ln(b / a) Figure 2. When bad calculations arise, traces that support high-speed edge rate signals eventually play the role of transmission lines, even though they are short. The alternating current that runs on a transmission. 0. This tool is javascript so it works on Windows, Mac, IOS, Android. Two properties characterize the PCB dielectric materials:A Transmission line calculator, Version 0. Figure 2. EMC Products and Services; EMC Organizations; EMC Periodicals. Structure of micro microstrip transmission line. 5. The average amateur does not like to. The output side only changes when you press calculate, and will display the characteristic impedance Z0 of the line, the impedance at the other end of the line, the velocity factor, the SWR at each end of the line, the matched loss of the line, and the total loss with your. The calculator uses the formula: L =20log10 ( λ 4 πd )+10log10 ( (4 π )2 Gt Gr )+Line Loss. β = 0. When placed at the antenna, an antenna tuner provides a 50-Ω impedance at the end of the 50-Ω line that is fed from a 50-Ω transceiver, resulting in a 1:1 SWR on the transmission line and at the radio. 1, makes the argument that a circuit with resistors, inductors, and capacitors is a good model for a transmission line. Select the Z0 button to calculate the characteristic impedance of the corresponding line. ), but. ac lin 101 1m 1meg * Using “Nutmeg” program to plot analysis . The impedance calculator in Altium Designer integrates with your PCB layer stack design tool and can calculate impedance for many transmission line geometries, including coplanar waveguides. It is improved for Rev 3 (July 2017. 71. Actual Impedance and Current Limits. A Grounded CPW transmission line calculator. The calculator shown below uses Wadell’s equations for differential impedance, which can be found in the seminal textbook Transmission Line Design Handbook. This calculator is a tool for designing balanced transmission lines with a specific desired characteristic impedance Zc and made of parallel square stock conductors of a given side length d. Building Open-Wire Lines If this were 1931, we would receive the following advice on building parallel transmission line: "An impedance of 600 ohms is both convenient and standard, however, and is entirely satisfactory for amateur systems. Vias (plated holes) are used to route electrical signals among different layers of a multilayer. From here, we can see that, for the dielectric constant and layer stack I’ve used, a ~16 mil microstrip will have about the. At these frequencies, the transmission line is actually functioning as an impedance transformer, transforming an infinite impedance into zero impedance, or vice versa. The electrical parameters may be determined from. It also gives an estimate of the mismatched loss if the mismatch is specified. The load reflection coefficient, in either model, can be obtained directly from the knowledge of the load and the characteristic impedance of the line as (1. Microstrip has conductors embedded in two dielectric mediums and cannot support a pure TEM mode. A transmission line should have a uniform characteristic impedance to avoid signal reflections. For example, a 2 inch microstrip line over an Er = 4. A common method for calculating theTransmission line calculators. The options are English system or Metric (SI) system. 3 Impedance calculation. To use it, first select the tolerance of the resistor: 10%, 5% or equal or smaller than 2%. The MWI-2017 Microwave Impedance Calculator software doesn’t. /˙. This calculator is designed to calculate the characteristic impedance of a broadside couple stripline (see diagram below). 354*Er/LOG (D/d)The characteristic impedance of a transmission line is purely resistive; no phase shift is introduced, and all signal frequencies propagate at the same speed. 45 for gold. 1 is the input impedance of a lossless transmission line having characteristic impedance Z0 and which is terminated into a load ZL. Calculate the input impedance of the combined line using a Smith chart if the speed of propagation on line (1) is 3 × 10 m/s and on line (2) 1 × 10 m/s. This implies that the resulting transmission line resonators are one-quarter wavelength long at 2 f 0 (i. This calculator computes the matched line loss for a transmission line using a model calibrated from data for the transmission line types built in to the calculator. 3, Kevin Schmidt, W9CF. 98mil. These are the characteristic impedance of the line, the load impedance,. , at z = z L) must be equal to the load impedance attached to that end! Q: But the result above is useful for the “old” V(z,Iz,Zz)()( ) description of transmission line activity. Field solvers. Transmission Line Calculator March 6, 2007. An online transmission line calculator is a web-based tool that allows users to calculate various parameters associated with transmission lines. • In general, the impedance line should be defined. There is also a dielectric material placed above the conductor. Figure 3. The complete development of transmission line theory is presented in Section 2. Stripline transmission line. The key is how fast the signal speeds are that you are working with. One option is to use the Smith Chart, which is a graphical method of doing. Kenneth L. All we need to do is calculate the proper transmission line impedance (Z 0 ), and length so that exactly 1/4 of a wave will “stand” on the line at a frequency of 50 MHz. A 50 Ω impedance profile defined for single nets routed on the top layer, hover the cursor over the image to display the settings for the same profile for layer L3. Sierra Circuits’ Transmission Line Reflection Calculator will greatly help you comprehend signal characteristics in the design phase. It is only equal to double the characteristic impedance in certain cases. Z V 3=0 V 4=0. L1 Z1, τ1 L1 = Z1τ1The source for formulas used in this calculator (except where otherwise noted) is the Design Guide for Electronic Packaging Utilizing High-Speed Techniques (4th Working Draft, IPC-2251, February 2001. The coaxial cable, along with the balanced two-wire, is the most common type of transmission line used in RF communications. Outer Diameter. Create an equation-based transmission line 50 cm in length. In electrical engineering, a transmission line is a specialized cable or other structure designed to. 3 shall be used. In this ideal scenario, no power is lost, and the VSWR value is 1 : 1, which signifies 100% transmission of the input power from the source. It’s particularly useful for determining the characteristic impedance (Z0), resistance per unit length (R), angular frequency (ω), inductance per unit length (L), conductance per unit length (G), and capacitance per unit length (C). Between a transmission line and a via structure with different impedance; Between a transmission line and some other RF structure with different impedance; Between a transmission line and a load component with different impedance; While there is not enough room to cover every taper design situation listed above, I’ll do my best to. L L ZjX= If the load is purely reactive (i. Just enter the given values for trace thickness, substrate heights, trace width, and substrate dielectric. Free Windows program for calculating the loss and impedance transformation. eqtxline = txlineEquationBased ( 'LineLength' ,0. It is composed of two conductors: a signal trace and a return path which is usually a ground plane. This transmission line impedance value is important in impedance matching and can be used to quantify when a transmission line has surpassed the critical length; take a look at the linked article to see how you can quantify permissible impedance mismatch. Transmission line. Single-stub matching is a very common method for impedance matching using microstrip lines at frequences in the UHF band (300-3000 MHz) and above. In other words, if the load impedance is equal to the transmission line characteristic impedance, the input impedance will be likewise be equal to Z 0 regardless of the transmission line length A. Most RF Coaxial Cables have an impedance of 50 ohms or 75 ohms. Overview. For an embedded (internal) microstrip, the formulas provided in paragraph 4. The first section, Section 3. 6 mils line width, and the effective dielectric constant is 6. Unit length of inductance L & unit length of capacitance C are the key elements of this calculation. com Microstrip Impedance Calculator. Mismatch can be specified as:The transmission line parameter calculator is a tool designated to compute characteristic line parameters give the type of the conductor and the configuration of a three-phase overhead transmission line. Rho: Conductor resistivity relative to copper. To use this tool, enter the values for. a. As always, use this information at your own risk. When you need to calculate impedance and other parameters to determine transmission line losses, you can use the integrated field solver in the Layer Stack Manager in Altium Designer ®. Compared to waveguides, microstrip is generally has a lower power handling capacity, and higher losses due to the fact that it is not enclosed. A transmission line drawn as two black wires. Delta Impedance, Rc (Ohms) =. Delta Impedance, Ra (Ohms) =. The following equation is used to calculate surge impedance: SI L = V 2 LL Z0 S I L = V L L 2 Z 0, where: The CST Cable Studio Impedance Calculator can be started from Cables > Impedance Calculator. The tool implements numerical solutions of Maxwell’s equations to render accurate and consistent results. This is to accommodate users who found the original ranges too limiting. Schematic of a wave moving rightward down a lossless two-wire transmission line. Perhaps the most common type of transmission line is the coax. Z. These transformers are lengths of nonuniform transmission line with a. 26 (p. e. This part of the dialog shows all the impedance related values in Ohms/length-unit as well as the transmission line limits specified in Amps. The two conductors are separated by a dielectric material. Chemandy on the other hand tells me 14. The transmission line input impedance is related to the load impedance and the length of the line, and S11 also depends on the input impedance of the transmission line. The microstrip calculator determines the width and length of a microstrip line for a. Twisted pairs are used with balanced signals. Home; Services. Home. These equations are relatively simple compared to other transmission line geometries, comprising only 2 interrelated equations for the microstrip impedance and. Under common mode driving (same magnitude, same polarity), the even mode impedance is the impedance of one transmission line in the pair. Use the Series and Shunt Impedance Calculator: to try your own impedances. It's easy to get a number out of an impedance calculator, but understanding what the number means and how to use it are the real challenges. When the length of a transmission line is longer than several wavelengths at the signal frequency, the two parallel conductors of the transmission line appear as a complex impedance. 0 value of the line to this point on the chart—50 Ω for a 50-Ω line, for example. Support for Coplanar Transmission Line Structures. exe, Differential Impedance Transmission Line Calculator : This calculator has been upgraded to Version 3. The Transmission Line Calculator is a handy tool for computing various properties of a transmission line. It is frequently used as such in antenna work when it is desired, for example, to transform the impedance of an antenna to a new value that will match a given transmission line. 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 upgrade now allows for input values significantly smaller than before. Capacitively Loaded Transmission Line Calculator. Picking it interactively in the 3D view and. In fact, striplines often make components such as band-pass filter's more accurately, with more symmetric roll-off and no lower cutoff frequency. Z0 = (60 / √εr) * ln ( (8h) / (w + s)) Where εr is the dielectric constant of the substrate material, h is the substrate height, w is the trace width, and s is the spacing between traces. Perhaps the most common type of transmission line is the coax. There are four factors that generally enter the solution of problems involving the changing input impedance along a line. 0-1)˚,ˇ%233+. Pasternack's RF Calculators and Conversions section provides engineers valuable and easy-to-use tools ranging from complex mathematical formulas to simple conversions. e. RF/Microwave Design; Digital Design; Layout Services. Verified with Agilent LineCalc and Agilent Momentum. Use the Series. TransLine. Understanding coax can be helpful when working with it. Z0,air Z 0, a i r = characteristic impedance of air. This can be set to zero, but the calculated loss will not include conductor losses. (For example, a two-section (N = 2) transformer has a 95. Rho: Conductor resistivity relative to copper. First, consider a microstrip. The Differential Pair Impedance Calculator is a specialized tool used in electrical engineering and signal integrity analysis to determine the characteristic impedance of a differential pair of transmission lines. 19. Z 0 unit of measurement is ohms (Ω) is also known as surge impedance. 60. Inputs. This calculator is designed to calculate the characteristic impedance of an embedded microstrip - a flat conductor suspended over a ground plane with a dielectric between it and another dielectric material above the conductor (see diagram below). This is read from the point where the circle you drew intersects the Re{ Z N} = 1 circle. INPUT DATA. Example 7. ECE145A/ECE218A Impedance Matching Notes set #5 Page 13 Basis for distributed matching using transmission line segments: the equivalent circuit model of a short transmission line. In most practical cases, the dielectric substrate is electrically thin, that is, h ≪ λ. 5. 946 for silver, or 1. A Microstrip is a type of electrical transmission line used to transmit RF signals and are commonly fabricated using printed circuit board (PCB) technology. While this calculator will provide a baseline, any final design considerations should be made towards loss, dispersion, copper roughness, phase shift, etc. 14159* (D+d)/2) C=7. On the other hand, in speaker wire, the insulation is usually quite soft, and a small amount (<1 mm) of incidental squishing of the cable will quite significantly change the distance between the conductors, and thus the impedance. While Z 1L is directly input into the relay as a setting, Z 0L is. Topic 56: Characteristic Impedance One of the most basic parameters of a transmission line is zo, its characteristic impedance. In other words, this is the impedance the signal actually experiences as it travels on an individual line. H 2 H 2 = subtrate height 2. The MWI-2017 Microwave Impedance Calculator software doesn’t replace sophisticated. 1kOhm, 1% tolerance: Brown Black Black Brown Brown. RF Two Wire Transmission Line Loss Calculator. In this case we use the Greek. 7-f9a2dced07~116. This is. Overview. e. 4% bandwidth with δz = 3. This is actually a general way to express impedance, but it requires an understanding of complex numbers. So, the dielectric at my 5-6GHz frequency range is 3. Picking from the CST Cable Studio Segments Navigation Tree. Figure 2 Self and Mutual Impedance in a Transposed Line . ϵr ϵ r = substrate dielectric. The Sierra Circuits Impedance Calculator uses the 2D numerical solution of Maxwell’s equations for PCB transmission lines. This software is intended to assist with microwave circuit design in predicting the impedance of a circuit made with Rogers High Frequency circuit materials. where Z 0,surf can be computed as specified in Eq. Overview. Short-Circuited Line, L = 0 (1. This can be set to zero, but the calculated loss will not include conductor losses. The two most common impedances. Use the Series and Shunt Impedance Calculator: to try your own impedances; Change Grid: S11, (ZL normalized to source impedance Z0). Source: Leon Salden, VK3VGA. 4. The input impedance seen at the other end will be a tangential function of the coil’s electrical length. Just as was the case with microstrip impedance calculators, stripline impedance calculators tend to rely on either the IPC-2141 formulas or on Wadell’s equations. 9)This calculator determines the differential microstrip impedance of a transmission line. Sierra Circuits’. 33 mA. This calculator helps translating the color bars from the resistor to its value. Solution of Wave Equations (cont. . The impedance calculator can also update the PCBS stackup with the current setup. 66, the trace height is 1. 151. 72mil. e. In the input section, provide the following data: Source. This paper documents the development and testing of a Transmission Line Parameter Calculator (TLPC), which computes the impedance parameters for short and medium transmission lines. Access technical papers, white papers, calculators, tools and more for circuit laminates, prepreg and bonding materials. This calculator is designed to calculate the characteristic impedance of a symmetric stripline - a flat conductor between two ground planes whose distance between the conductor and the planes is the same for both reference planes. One of the features of this type of microstrip is the coupling between lines. It is widely accepted that the most accurate impedance calculations are produced with a 3D field solver due to the complex geometry in any PCB. Transmission Line Details by Dan AC6LA. Height: Height of the substrate. A lossless transmission line has characteristic impedance = 300 Ω, is 6 3 wavelengths long, and is terminated in a load impedance 25 Ω. Adding shunt inductance moves clockwise along constant admittance circles. November 15, 2023 by Rafay Javed. With PCBWay impedance calculator, you can calculate the approximate impedance of your PCB / high frequency circuit board. Simulation Setup. Here's a spreadsheet that performs via-hole inductance for microstrip circuits. Cable Impedance Calculator. This transmission line calculator calculates the impedance at input and attenuation of a given transmission line once terminated with the given load. 4) 2. Analyze. wavelenggh λ = 15 x 10 3. The width of the conducting layer is important to calculate the radiation intensity since it directly affects. I. Without repeating everything in that article, the input impedance depends. This calculator finds both odd and even transmission line impedance. V~(z) = V~+ 0 (ejβz +ΓLe−jβz) I(z) = V~+ 0 Z0 (ejβz − Γe−jβz) (1) (2. A BASE = Base Amps. This information is crucial for designing high. The green boxes turn red if the numbers are outside the range for reliable calculation. The microstrip impedance calculator shown above uses Wadell’s equations for microstrip impedance, which can be found in the seminal textbook Transmission Line Design Handbook. This is entirely different from leakage resistance of the dielectric separating the two conductors, and the metallic resistance of the wires themselves. 1. 3. How much power does the generator deliver? Answer: The diagram for this problem is given in the following diagram:Differential impedance: This is the impedance of a pair of transmission lines. If is the characteristic impedance of the line, then () / = for a wave moving rightward, or () / = for a wave moving leftward. The software also has some capabilities for predicting transmission line losses as well. 4. Equation 3. Of course, this only occurs at resonant points resulting in a standing wave of 1/4 cycle (the line's fundamental, resonant frequency) or some odd multiple (3/4, 5/4, 7/4, 9/4 . When in doubt, use 1 for copper, . Although implementations vary, the wire diameter is usually about 1 mm and and the wire spacing is usually about 6 mm. This calculator is a tool for designing balanced transmission lines with a specific desired characteristic impedance Zc and made of parallel square stock conductors of a given side length d. Coax Impedance (Transmission Line) Calculator. Users need only specify the material. 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. Inductor Q Factor. 3. Transmission Line Design Information In these notes, I would like to provide you with some background information on AC transmission lines that may be useful to you in your project. The calculator then uses a formula to calculate the width and spacing of the trace or transmission line required to achieve the desired characteristic impedance. There are some advantages to using a. 3, respectively. Description. You can input the capacitance. . 4. c is the speed of light in a vacuum (approximately 3 × 10^8 meters per second). or. The impedance ratio has a peak at about 1. 6 + j0. With our handy calculator, you can choose from 50 Ohm, 75 Ohm, 93 Ohm and 95 Ohm coaxial cables. Any transmission line can be characterized by transmission line parameters such as resistance, shunt conductance, inductance, and capacitance. Vias (plated holes) are used to route electrical signals among different layers of a multilayer. Copper is a suitable material for flat conductors. The wave length of transmission line is derived from the formula: L (wavelength in meters) = 300,000/KHz. 45 for gold. Zo (unloaded trace impedance, Ohms) = Tpd (unloaded propagation delay, ps/unit len) = Cl (distributed capacitve load, pf) =. • HFSS computes the characteristic impedance of each port in three ways — as Zpi, Zpv, and Zvi impedances. The characteristic impedance (Z o) of a microstrip transmission line can be calculated using the active calculator or the equations at the bottom of the page. Also, what. This can be achieved by regulating the inner and outer diameter of the coaxial cable, along with the. TLDetails includes a plot function that allows you to plot the matched line loss, the true velocity factor, or the true characteristic impedance magnitude, over a frequency range of either 0. Differential pair impedance calculators will return at least two important values, and it's important to understand what these values mean/how to. The Transmission Line Calculator is a handy tool for computing various properties of a transmission line. In this section, zo is calculated for four common transmission lines — coaxial, twin-lead, parallel plate, and microstrip. High speed measurement tools. In other words, the line impedance at the end of the transmission line (i. Our RF calculators and converters will provide the figures you need for your radio frequency engineering needs. 1. Most formulas calculate impedance from width, because width is a boundary condition and it's easier to calculate forward from a boundary condition, than backwards to reconstruct it. Our capacitive reactance calculator helps you determine the impedance of a capacitor if its capacitance value (C) and the frequency of the signal passing through it (f) are given. Edge Coupled Stripline Differential Impedance Calculator. First, calculating the line impedance: taking the 75 Ω we desire the source to “see” at the source-end of the transmission line, and multiplying by the 300 Ω load resistance, we. = 2π/15 x 10 3. The equations for the voltage and current anywhere (any z) on a transmission line are. Equation 3. Z. Draw a circle through this point around the center. The even mode impedance is simply the impedance of a single line when the two lines are driven in. Open Wire Feeder Impedance Calculator. Use the "Spin Buttons" to adjust the values in the box. The Coplanar Transmission Line Calculator is a valuable tool used in electrical engineering to determine the characteristic impedance of a specific transmission line. In terms of the characteristic impedance in line 1, mutual impedance. TX-LINE software is a FREE and interactive transmission-line utility for the analysis and synthesis of transmission-line structures that can be used directly in Cadence ® AWR ® Microwave Office ® software for matching-circuits, couplers, and other high-frequency designs. 42 and later, which calculates all three symmetrical components (zero, positive, and negative sequence values) of the line impedance. TX-LINE software is a FREE and interactive transmission-line utility for the analysis and synthesis of transmission-line structures that can be used directly in Cadence ® AWR ® Microwave Office ® software for matching-circuits, couplers, and other high-frequency designs. The K values for the various transmission lines are also copied from his Transmission Line Details windows software. Transform Delta to Y: Add Series/ Parallel Resistor: None R in Series with R1 R in Series with R2 R in Series with R3 R in Parallel with Ra R in Parallel with Rb R in Parallel Rc. Such a microstrip is constructed with two traces referenced to the same reference plane with a dielectric material between them. Microstrip Transmission Line Models. e. The normalized input impedance for that transmission line is read from the Smith Chart to be 1 - j0. The result also depends on the length and phase propagation constant of the line. Black dots represent electrons, and the arrows show the electric field. The radius of the circle is the reflection coefficient G , where the radius to the edge is 1. Coplanar Waveguide Calculator. 1, makes the argument that a circuit with resistors, inductors, and capacitors is a good model for a transmission line. An example follows. Transmission Line Details by Dan AC6LA. Assuming both are accurate enough. This calculator is designed to help calculate the value of the resistors R1 and R2 to be used in T-pad attenuator. This Mantaro calculator tells me that I need a trace width of 11. L to the beginning of the transmission line, so that we can replace the transmission line with its input impedance Z in : Note by voltage division we can determine: ()in g g in Z V zV ZZ =− = + A And from Ohm’s Law we conclude: ()g g in V Iz ZZ =− = + A And thus, the power P in delivered to Z in (and thus the power P abs delivered to the. To achieve matched impedance, multi-section transformers are connected between the feeder transmission line of characteristic impedance Z 0 and the load impedance Z L. [2] Calculate the top layer signal end impedance: Two tools are giving Zo=48 and Zo=47. 6. This can be achieved by regulating the inner and outer diameter of the coaxial cable, along with the. While commonly constructed using printed circuit boards, this structure can also be built using other materials as long as there is a conductor separated from. Enter the Outer Diameter (D), Outer Diameter (d), and Permittivity. Coplanar waveguide transmission line calculators (CPW, GCPW) I’ve just emerged from a rabbit hole & thought I’d share what I learned regarding available impedance calculators for coplanar waveguide (CPW) and coplanar waveguide w/GND (GCPW). 5*3. Assume microstrip line for which propagation occurs with. Then, simplify the expression inside the square root. 4. Impedance calculationEven and Odd Mode Impedance.