1: 300 Ω 300 Ω twin-lead. Since the argument of the complex exponential factors is 2βl, the frequency at. (For example, a two-section (N = 2) transformer has a 95. Online Transmission Line Calculators. Port Characteristic Impedance, Zo (Ohms) =. 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. Transmission-Line Calculator. The Impedance Calculator will calculate the: The impedance of a RLC circuit when resistance, capacitance and inductance are given. Webb ESE 470 16 Short-Line Model How we choose to model the electrical characteristics of a transmission line depends on the length of the line Short-line model: < ~80𝑘𝑘𝑚𝑚 Lumped model Account only for series impedance Neglect shunt capacitance 𝐼𝐼and 𝜔𝜔𝜔𝜔are resistance and reactance per unit length, respectivelyLadder line spreader built from black irrigation extension tube and a cable tie. Picking from the CST Cable Studio Segments Navigation Tree. 0 MHz. The free impedance calculator shown below. The average amateur does not like to. Verified with Agilent LineCalc and Agilent Momentum. and therefore alter the characteristic impedance of the transmission line! Generally, speaking, we find that this transmission lines are capacitively coupled (i. 3. Cadence/AWR. Online VHF UHF. Z PU = Per Unit Impedance. Enter the number n n of impedances in parallel as a whole number and press "Enter". A common method for calculating theTransmission line calculators. Because designing a transmission line means you keep manipulating the characteristic properties of a twisted pair, to see which values will give the best results. Nist, KQ6QV has free software for calculating arbitrary transmission line impedance, as well. Pi-Matching Impedance Network Calculator. 7. 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 ®. A BASE = Base Amps. The units are miles when using English system, or kilometers when using the Metric (SI) system. Use our free online app Characteristic Impedance of a Transmission Line Calculator to determine all important calculations with parameters and constants. By substituting equation 5 into equation 4, we can obtain the input impedance, as given in equation 6: From equation 6, we can conclude that the input impedance of the transmission line depends on the load impedance, characteristic impedance. ) Proposed form of solution: Using: It follows. LPARA, an existing software at The Trinidad and Tobago Electricity Commission (T&TEC), has been. The relative permittivity of the medium ϵr ≈ 1 ϵ r ≈ 1 for the. In other words, the line impedance at the end of the transmission line (i. This is actually a general way to express impedance, but it requires an understanding of complex numbers. Although implementations vary, the wire diameter is usually about 1 mm and and the wire spacing is usually about 6 mm. View All Tools. Characteristic Impedance Ω. Overview. This can be set to zero, but the calculated loss will not include conductor losses. The microstrip is a very simple yet useful way to create a transmission line with a PCB. The formula for S11 treats the transmission line as a circuit network with its own input impedance, which is required when considering wave propagation into an electrically. e. It supports both balanced and unbalanced lines. ) X C = Capacitor Bank Impedance (ohms) X C-PU = Capacitor Bank Per Unit Impedance. The substrate parameters (ε r and h) and the frequency of interest are required. On a reference plane, there is an edge coupled differential microstrip line with two traces. Enter the relative permitivity, width of the trace, the ground plane spacing, and the substrate thickness to calculate the characteristic impedance. This calculator can calculate the impedance and propagation delay of the embedded microstrip. Combine this with increased clock frequencies and data rates and the result is a critical challenge to high-speed design. Design a transmission line segment that matches 300 Ω to 50 Ω at 10 GHz using a quarter-wave match. A Clemson ECE635 Project by Adam Schreiber and Jason Byers. Figure 2 Self and Mutual Impedance in a Transposed Line . This technique doesn’t work for wide band requirements, but is a simple way to achieve this at a specific. Each grid of the insulator can be thought of as 4 capacitors each. The Differential microstrip impedance calculator is used to compute the differential (Zd) and single-ended impedance (Zo) of an edge-coupled microstrip line just by entering the width, separation and thickness of the. The Coplanar Transmission Line Calculator is a valuable tool used in electrical engineering to determine the characteristic impedance of a specific transmission line. There are some advantages to using a microstrip transmission line over other alternatives. Press Analyze to see the results. A transmission line drawn as two black wires. Cable Impedance Calculator. , it appears that they are connected by a capacitor): Figure 7. Gt is the gain of the transmitting antenna. If the ground plane is treated as a universal ground, then the model of a segment of length Δz is as shown in Figure 2. 78, and operating at a frequency of 7. The key is how fast the signal speeds are that you are working with. Black dots represent electrons, and the arrows show the electric field. In some cases, users require a custom impedance value. matches the transmitter (or transmission line, if it’s placed at the antenna) and the output impedance matches the load. 4mil and the dielectric thickness to the first intermediate layer (this is a 4-layer board) is 6. The Differential microstrip impedance calculator is used to compute the differential (Zd) and single-ended impedance (Zo) of an edge-coupled microstrip line just by entering the width, separation and thickness of the trace along with the dielectric thickness and constant of the coupled line. A transmission line drawn as two black wires. What this means is that the center point of the chart now represents 50 +j 0 ohms–a pure resis-tance equal to the characteristic impedance of the line. Just about any signal in a high-speed design can behave like a transmission line, including data, memory, clocks, controls, and any other nets in the design. 8. A microstrip is a type of transmission line in which a strip of a conducting material like copper is mounted on a dielectric material and routed to a. 2 also shows that the impedance transformation ratio at low frequencies is reduced from its. s. d is the distance between antennas (in meters). This calculator will help you calculate the guided wavelength, provided the dimensions of the microstrip are given as well as the velocity of propagation, the microstrip material's dielectric constant, and the input frequency. When you solve Maxwell's Equations for electromagnetic wave propagation, the electric field solutions look like this: E (z,t) = E * cos (γz - ωt). Visit to learn more about our other electrical engineering tools. In this case a rectangular form is used. Type C Pulse Forming Network. ϵr ϵ r = substrate dielectric. This calculator is designed to calculate the characteristic impedance of an edge-coupled microstrip. For now let us focus on the single ended impedance. 5rad. The relative permittivity of the medium ϵr ≈ 1 ϵ r ≈ 1 for the. There are some advantages to using a. A stripline is formed by a conducting strip in a substrate sandwiched by ground planes above and below the strip. Enter the source characteristic impedance and the load impedance then press "Calculate" below. View All Tools. 3: Normalized characteristic impedance and normalized effective permittivity of a microstrip line as a function of u = w / h. This implies that the resulting transmission line resonators are one-quarter wavelength long at 2 f 0 (i. 1, makes the argument that a circuit with resistors, inductors, and capacitors is a good model for a transmission line. To use the calculator, place values in either the velocity of propagation field or the dielectric constant field. The first section, Section 2. Coaxial Cable Impedance Calculator. Title: TransmissionLine. Adding shunt inductance moves clockwise along constant admittance circles. It accounts for ground wires, ground return, and mutual coupling between circuits. 1 to 100 MHz or 1 to 1000 MHz. 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. Find the transmission or propagation parameter of the transmission line or wave guide whose wavelenggh λ = 15 x 10 3. Overview. 0 Power Base: The system voltampere base in MVA. Reference: R. The K values for the various transmission lines are also copied from his Transmission Line Details windows. 5*3. 33 mA; end: V=0, I=13. The lines operate at 300 MHz. “The Surface Microstrip Impedance Equation”. A common method for calculating theThis section develops the theory of signal propagation on transmission lines. You can input the capacitance. One of the features of this type of microstrip is the coupling between lines. Distance relays require knowledge of the positive-sequence (Z 1L) and zero-sequence (Z 0L) impedances of the line. Modeling approximation can be used to understand the impedance of. Transmission Line Details by Dan AC6LA. The microstrip calculator determines the width and length of a microstrip line for a. This example shows how transmission-line theory in conjunction with simulated values for characteristic impedance can be used to quickly evaluate the crosstalk between two microstrip lines. 1, the top (visible) traces comprise one conductor, whereas the ground plane (underneath, so not. 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). As these additional effects are included in a transmission line model, the resulting impedance equations become very complex. The software also has some capabilities for predicting transmission line losses as well. These are the characteristic impedance of the line, the load impedance,. It is one of the most popular transmission lines used in the VHF frequency range. When in doubt, use 1 for copper, . The equations that are used to calculate stripline impedance are simple, but there is a large number of terms, which includes a. Ω/mΩ/in. 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. The upgrade now allows for input values significantly smaller than before. to NF. The impedance values can be stated in either phase coordinates (A, B, and C) or sequence coordinates (zero, positive, and negative sequence). Enter values for W and L for a microstrip line to determine its Zo and Electrical Length. For example, if you wish to input "25000000", just type "25M" instead. Example 7. This calculator is designed to calculate the characteristic impedance of an edge-coupled microstrip. Models have been created to approximate the characteristics of the coax cable transmission line. The impedance calculator can also update the PCBS stackup with the current setup. Impedance Calculator. Equations used to make these calculations can be found in the book [1], and are also. Reflection coefficient is also. 19. 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. The velocity of light in the transmission line is simply: For a TEM transmission line (coax, stripline) with air dielectric the velocity of light reduces to the constant "c" which is the velocity of light in a vacuum (2. ATLC cannot calculate Zo for conductors in an unbounded space, so the conductors must be contained within a grounded bounding surface. or any device with a web browser. 4. The circuit schematic for the Type C Pulse Forming Network is shown below. Models have been created to approximate the characteristics of the wire microstrip transmission line. 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 complete development of transmission line theory is presented in Section 2. This transmission line calculator. Pasternack's RF Calculators and Conversions section provides engineers valuable and easy-to-use tools ranging from complex mathematical formulas to simple conversions. These radio frequency calculators help with unit conversion, attenuator design, antenna design, radars, and various other basic calculators. Include both the pcb dielectric thickness as well as the wire insulation in the height calculation. 1. eqtxline = txlineEquationBased ( 'LineLength' ,0. The Transmission Line Calculator is a handy tool for computing various properties of a transmission line. Thus, the voltage ‘V1’ at line 1 will not only depend on current ‘I1’ in line 1 (through impedance ‘Z0’ of line 1). Transmission Line Calculator March 6, 2007. 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). The edge couple differential symmetric stripline transmission line is a common technique for routing differential traces. This can be achieved by regulating the inner and outer diameter of the coaxial cable, along with the. An online transmission line calculator is a web-based tool that allows users to calculate various parameters associated with transmission lines. 2. This form of microstrip is composed of two traces. AC Transmission Line Impedance Parameters AC transmission is done through 3-phase systems. [2] Calculate the top layer signal end impedance: Two tools are giving Zo=48 and Zo=47. It is improved for Rev 3 (July 2017. Vias (plated holes) are used to route electrical signals among different layers of a multilayer. The Excel based tool (see link below) calculates the capacitance and inductance per unit length as well as the impedance of a transmission line. rlgc_params = s2rlgc(___,z0) transforms multi-port S-parameter data into a frequency-domain representation of an RLGC transmission line using a characteristic impedance of z0. c is the speed of light in a vacuum (approximately 3 × 10^8 meters per second). Formulas. 5 Power Flow on a Terminated Lossy Line. Use our free online app Characteristic Impedance of a Transmission Line Calculator to determine all important calculations with parameters and constants. Full Line Constants Feature Overview This document describes the Full Line Constants feature in PLS-CADD, available in v15. The odd mode impedance, Z 0,o, is given by the following equation: Eq. Multiple dielectric transmission line calculator using a 2D field solver to compute the transmission line characteristics from the circuit trace dimensions entered by the user. Assume microstrip line for which propagation occurs with. A Clemson ECE635 Project by Adam Schreiber and Jason Byers. 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 . HF Antenna Trimming Chart. The following steps outline how to calculate the characteristic impedance (Z0) for a Transmission Line using the given formula: First, determine the values of R, w, L, G, and C. H eff = H 1 + H 2 2 H e f f = H 1 + H 2 2. Z. 3 | TRANSMISSION LINE CALCULATOR where γ, the complex propagation constant is given by: If only a forward-propagating wave is present in the transmission line (no reflections), dividing the voltage V by the current I gives the characteristic impedance Z 0, or wave impedance of the transmission line:Microwave Impedance Calculator Rogers Corporation. Thickness: Thickness of the stripline conductor. 3, respectively. Using a Differential Pair Impedance Calculator. If the calculator does not provide velocity (or velocity factor), it's probably because you can use e_eff instead. 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. Where, Γ = Reflection coefficient. This online microstrip impedance calculator calculates the characteristic impedance of the microstrip (Ω), W/H ratio, and effective dielectric constant (εe) by entering the value of dielectric material relative permittivity (εr), the width of the copper trace (W), and dielectric height (H). Call us: +1 (800) 763-7503 Email us: through our Customer Care form. To summarize, the Stripline Impedance Calculator enables engineers to calculate the characteristic impedance of a stripline based on its geometric dimensions and dielectric properties. The characteristic impedance of a. It is possible to ascertain the relevant behaviors of a transmission line using elementary circuit theory applied to a differential-length lumped-element model of the transmission line. 1: Impedance-matching using a quarter-wavelength transmission line. November 15, 2023 by Rafay Javed. Height: Height of the substrate. Line Length Units: The line length units specify the measurement system to use when entering the line length. 6. This calculator is a tool for designing balanced transmission lines with a specific desired characteristic impedance Zc and made of parallel square stock. Incorrect line impedance values in transmission line models can lead to inadequate relay settings that can potentially lead to distance element misoperations. a. Zo (unloaded trace impedance, Ohms) = Tpd (unloaded propagation delay, ps/unit len) = Cl (distributed capacitve load, pf) =. Understanding coax can be helpful when working with it. Suppose that Zg=50 Ohms, ZA=50 Ohms, Z0=200 Ohm, and that the line is a quarterwavelength long. The MWI-2017 Microwave Impedance Calculator software doesn’t replace sophisticated. 3, Kevin Schmidt, W9CF. 16. g. The given data. The nice part about coax is that it can be bent and flexible unlike most pcb transmission lines. Where: Z0 Z 0 = characteristic impedance of the asymmetric stripline in ohms (Ω). As also noted in the picture, the subsequent calculations are on the: [2] top-layer single-end impedance; [3] top-layer differential impedance; [4] inner-layer differential impedance. 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). Except in the case of a handy little design program called the MWI-2010 Microwave Impedance Calculator, available for free download from the Rogers Corporation website. where Z 0,surf can be computed as specified in Eq. e. Figure 5. In transmission line theory, the mismatch loss (ML) is the ratio of incident power (Pi) to the difference between incident and reflected power (Pr). Impedance Calculator. Both input impedances will determine the input impedance of transmission line #1. The two conductors are separated by a dielectric material. Wave Equations for Transmission Line Impedance and Shunt Admittance of the line . The result also depends on the length and phase propagation constant of the line. Fc=11. Impedance mismatch/discontinuity between the transmission line/cable to the connected load/component leads to a small amount of incident signal power reflect back to the source. It’s particularly useful for determining the characteristic impedance. m s: the speed of light. The bottom line is : the impedance of the matching section is equal to the square root of the antenna impedance times the feed line impedance. 5. Comments. In most practical cases, the dielectric substrate is electrically thin, that is, h ≪ λ. 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. 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. The alternating current that runs on a transmission. The wires exhibit considerable series inductance whose reactance is. A microstrip is a type of transmission line in which a strip of a conducting material like copper is mounted on a dielectric material and routed to a ground plane. These are considered to be standardized impedance values with cables readily available. To get around the above drawbacks of typical stripline impedance calculator applications like the one shown here, some more advanced methods are needed to determine impedance. Calculating Characteristic Impedance. m. In this example, we consider a device. Voltage Base: The line-line voltage base in KV. (FWIW, I’m using Kicad 6. You can easily construct your own transmission lines with a. At f=0 Hz: input: V=0, I=13. 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. 60. Coverage Maps by Roger Coudé, VE2DBE. This is a required field. The effective dielectric constant drives the length of the taper, this effect was not. One thing is for sure: When you are routing a high-speed PCB design you are going to be working with impedance-controlled routing and. Track Thickness: mm. 3. The impedance values can be stated in either phase coordinates (A, B, and C) or sequence coordinates (zero, positive, and negative sequence). In general, it is double the odd-mode impedance, which is the value we care about for differential signaling, as it is used in high-speed PCB design. Grounded CPW transmission line impedance calculator. 1. The amplitude of the peak can be controlled by changing the value of the odd-mode impedance. Back in the 1930s, the Smith chart was a staple of high-frequency work. The objective of this paper is to present techniques to estimate the zero-sequence line impedance of all sections of a three-terminal line and the Thevenin equivalent impedance of the transmission. 3 shall be used. 14159* (D+d)/2) C=7. Line Length: This is the value of the distance of the transmission line. The even mode impedance is simply the impedance of a single line when the two lines are driven in. 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. Home; Site Map; CPW (grounded) line calculator. 0041. 2 and: Eq. The width of the conducting layer is important to calculate the radiation intensity since it directly affects. These quantities - source impedance, line impedance and load impedance, respectively - must equal one another (impedance matching]) to ensure the efficient transmission of power. This calculator helps you calculate the characteristic impedance of a coaxial cable given its dimensions. Create an equation-based transmission line 50 cm in length. Microstrip Transmission Line Models. Common Mode Impedance (Zc) is the impedance when signals travel in-phase. This parameter is used for the loss calculations. Overview. 125) wavelength long, using 50 ohm line with a velocity factor of 0. 2, and Section 2. 6. 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. The characteristic impedance is given by: Eq. 2 and 3. The tool implements numerical solutions of Maxwell’s equations to render accurate and consistent results. These equations are rather complex, comprising a set of 67 interrelated equations and parameters, which includes a requirement to calculate elliptical integrals to solve these equations. Figure 25. Z V 3=0 V 4=0. The parameters computed are the resistance R, reactance X, susceptance B, and conductance G. So, the dielectric at my 5-6GHz frequency range is 3. 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. 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). Though it's important to note that these properties are distributed throughout the entire length of the transmission line, lumping them all together we can model a transmission line as: The characteristic impedance is then: $$. Home. Input Impedance of a Transmission Line with a Load Impedance Recall from the previous chapter that we chose z=0 to be at the load, and everything to the left of that point has a negative value of z. , 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. G = 2πσ ln(b / a) Figure 2. This allows the stored energy, capacitance, inductance and impedance to be found. Solution of Wave Equations (cont. exe, Differential Impedance Transmission Line Calculator : This calculator has been upgraded to Version 3. AS9100D – Military & Aerospace; IPC-A-600 Inspectors;Again, we will look at a transmission line circuit in Figure 1 to find the input impedance on a transmission line. Radius. This is a required field. Z0 = V~+ 0 I~+ 0 = R + jωL γ Z0 = −V~− 0 I~− 0 = R + jωL γ (8) (9) (8) Z 0. An embedded microstrip is a microstrip transmission line or flat conductor separated from the ground place via a dielectric material. A microstrip width calculator can calculate the width of a microstrip. It's also explained on our DK and DF Extraction page. Initial planning studies typically only consider balanced, steady-PCB stackup, signal integrity and controlled impedance: Signal integrity tools: Stackup design. Description. With hundreds of coaxial RF cables in-stock and ready to ship worldwide immediately, our coax capacitance calculator lets you calculate the impedance of a coax by allowing you to enter the outer diameter dielectric width and inner conductor diameter. The wave length of transmission line is derived from the formula: L (wavelength in meters) = 300,000/KHz. In this Type C PFN, each capacitance has an initial condition voltage of 1000 V. Next, substitute the values into the formula: Z0 = sqrt ( (R + jwL) / (G + jwC)). Return to the top. , the resistive component is zero), the input impedance is: Z 0,β A ZL=Z0 in 0 ZZ= Introduction. A Re-engineered Transmission Line Parameter Calculator. 78, and operating at a frequency of 7. The video. Articles; Tools; Contact Us; Main Menu. 2: A broadband RF balun as coupled lines wound around a ferrite core: (a) physical realization (the wires 1– 2 and 3– 4 form a single transmission line); (b) equivalent circuit using a wire-wound transformer (the number of primary and secondary windings are equal); and (c) packaged as a module (Model TM1-9 with a. 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. High speed measurement tools. This tool can calculate. Sierra Circuits’ Transmission Line Reflection Calculator will greatly help you comprehend signal characteristics in the design phase. Without repeating everything in that article, the input impedance depends. 71. 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. Hopefully, you can see how this inductive reasoning continues indefinitely. This transmission line calculator calculates the impedance at input and attenuation of a given transmission line once terminated with the given load. Use the Series. These impedance values thus determined can. Differential Microstrip Impedance Calculator (Using Zo) Embedded Microstrip Impedance Calculator. Microstrip Transmission Line Models. Embedded microstrips are commonly crafted using printed circuit boards, although other. • THE impedance of the transmission line (may be time dependent) • The instantaneous impedance of the transmission line • The Characteristic impedance of the transmission line Just referring to “…the impedance” may be a bit ambiguous Eric Bogatin 2000 Slide -10 MYTHSFind Characteristic Impedance of a Transmission Line Calculator at CalcTown. Frequency span ±. The near-end and far-end crosstalk obtained from the built-in characteristic impedance calculator and theory is verified through 3D FDTD simulations using. Satellite Look Angle Calculator. Coaxial Cable Impedance Calculator. Thus, for this system, VSWR = 1:1 (i. Follow @SpokCa. The development of transmission line theory is presented in Section 3. 66, the trace height is 1. Type in a Radius and Spacing and press "Calculate". 24 hours a day, 7 days a week. These equations are rather complex, comprising a set of 67 interrelated equations and parameters, which includes a requirement to calculate elliptical integrals. Edge Coupled Stripline Differential Impedance Calculator. , USB. Terminal impedance Z term & characteristic impedance Z 0 are the key terms of this calculation. 3 Impedance calculation. of each conductor and equal mutual. 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. Clemson Vehicular Electronics Laboratory: Transmission Line Impedance Calculator. 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 . If the impedance of the TDR unit is known via proper calibration, then the Z 0 of the transmission line attached to the TDR unit may be determined. e. 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. Short-Circuited Line, L = 0 (1.