Differential line impedance calculator. Each S-parameter (Sij) has a real magnitude and a phase in the complex part. Differential line impedance calculator

 
 Each S-parameter (Sij) has a real magnitude and a phase in the complex partDifferential line impedance calculator  Z diff = 2* Zo (1 - 0

To calculate the impedance, I use Saturn PCB impedance calculator software, Inc - PCB Toolkit V8. Pi-Matching Impedance Network Calculator. 6. Take note that this assumes that the distance between the conductor and the planes is not the same for both reference planes; hence the asymmetric term. With our handy calculator, you can choose from 50 Ohm, 75 Ohm, 93 Ohm and 95 Ohm coaxial cables. Edge Coupled Stripline Impedance Calculator. A quarter-wave line will present an input impedance of $frac{Z_{char}^2}{Z_{load}}$The impedance of the structure is the ratio of the voltage between, and the current in, the conductors. 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. Commonly fabricated with printed circuit board (PCB) technology, a microstrip antenna calculator tool is an electrical transmission line that is. 1. Isolation of power source noise 3. 5 V and a. This calculator assumes the distance between the two reference planes to be an equal distance. 6. frequency domain method, for transmission line effects. A symmetrical stripline is shown in Figure [Math Processing Error] 3. Asymmetric Stripline Impedance Formula. Figure 81 shows the topology. , DDR, HDMI, Gigabit Ethernet). This can be achieved by regulating the inner and outer diameter of the coaxial cable, along with the. Let's match the impedance of the same signal since differential pair routing is completed when the impedance is matched properly. •The propagation delay time on the line should not exceed 5. Figure 1. The figure-1 above depicts differential microstrip line. com Edge Coupled Stripline Impedance Calculator A calculator for computing the impedance of an edge coupled stripline. g. Solution of Wave Equations (cont. As we’ve seen above, the S-parameters and input impedance of a transmission line are the correct tools for describing signal reflection at the load end of a transmission line. 1. I see that Dielectric Constant is 4. Create a new impedance profile, then select Single-Coplanar or Differential-Coplanar from the Impedance Profile Type drop-down list. Speedstack is the stackup design tool of choice for professional PCB Designers fabricators and brokers who have a requirement to document and design stackups drill plans and material requirements complete with high. this type of termination. Often when working with wires it is easy to create large return path loops if one is not paying close attention. Disc Air Capacitor Calculator; Impedance Calculator : XL, XC; Inductors, Transformers. The Smith Chart graphically maps S11=reflection coefficient= (ZL-Z0)/ (ZL+Z0) to Load Impedance (ZL), normalized to Z0 (source impedance = center of chart). I have already some experience on single ended controlled impedance but this is my first. Controlled impedance is important for solving signal integrity problems, which is the propagation of signals without distortion. Impedance Calculator. Here lies the challenge: impedance calculators must balance speed and accuracy. 71. In fact, striplines often make components such as band-pass filter's more accurately, with more symmetric roll-off and no lower cutoff frequency. This is 1. Embedded Microstrip Impedance Calculator. • As shown in Figure 1, traces should be 100-Ω(±5%) differential impedance of differential microstrip or differential stripline. Edge Coupled Microstrip Impedance Calculator This tool helps calculate the impedance of an edge-coupled microstrip. Differential Pair Impedance (Z_diff) = (2 × Z_single) / sqrt(1 + (2d / s)) Where: Differential Pair Impedance (Z_diff) represents the characteristic impedance of the differential. If there is a significant amount of charging current, it is necessary to modify the scheme to prevent a misoperation. Note: Units do not matter for this calculation as long as they are consistent. This assumes ~0 trace thickness. 03556mm. when two coupled tracks are used to give a differential impedance. Differential impedance: This is the impedance of a pair of transmission lines. Modeling approximation can be used to understand the impedance of the edge couple differential stripline transmission line. One should always check carefully whether a calculator implements these equations under the appropriate approximations. H 1 (Dielectric thickness) : mm mils. 81 mm). 035 mm) h is the Thickness of dielectric. Characteristic impedance in Ohms : Differential microstrip impedance in Ohms : *Note: This calculator is valid for (W/h) in range from 0. This PDF document provides a comprehensive guide on how to calculate the impedance of various PCB structures, such as microstrip, stripline, and differential pairs. Vias (plated holes) are used to route electrical signals among different layers of a multilayer. It is the differential impedance between them that matters. 7. The characteristic impedance is given by: Eq. The differential impedance depends upon the D/H ratio. *The structure may propagate in 3 modes: coplanar waveguide, coupled slot lines and microstrip. They are equal when the line is loaded in its characteristic impedance. Altium Designer’s differential line impedance calculator will set up your impedance-controlled differential pair routing widths for you. INPUT DATA. Take note that this assumes that the distance between the conductor and the planes is not the same for both reference planes; hence the asymmetric term. 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. At some point the amplitude will stay constant. Otherwise you could lose data). I selected driven-modal solution for a number of modes of 2. In high-speed digital protocols, data is sent over single-ended traces in a PCB that is impedance controlled; each individual trace is designed to have a specific impedance. you need to make sure all of your data reaches the receiver before the clock triggers. 6. INPUT DATA. The calculator is available in the Electrical Domain in Constraint Manager, from theDifferential signaling in flex circuits follows the design method of surface microstrip transmission lines. The required values are trace thickness, substrate heights, trace width, and subtrate dielectric in the calculator above and press the "calculate" button. 347 e -2. Incidentally, the trace thickness parameter does have a. **Note: Like our stripline impedance calculator, all of our RF calculators allow SI prefix input. With PCBWay impedance calculator, you can calculate the approximate impedance of your PCB / high frequency circuit board. Description. The answer lies in the spacing between the traces in the pair. Differential Pair Calculator The Differential Pair Calculator is used to perform what-if analysis to determine what values of Primary gap and width are needed to get specific differential and single line impedance. Differential Pair Calculator The Differential Pair Calculator is used to perform what-if analysis to determine what values of Primary gap and width are needed to get specific differential and single line impedance. The differential impedance of a PCB is simply the current to voltage ratio on pairs of transmission lines driven in differential mode. A microstrip width calculator can calculate the width of a microstrip. Broadside-coupled Asymmetric Stripline. The second type is common mode noise which is. The calculator will process the values and display the. At low frequencies near 0 GHz, the input impedance is inductive since. Differential impedance between the data lines should be 90 Ω +/- 15%. The difference is in the definition of the voltage and currents in the modes as shown in Figure [Math Processing Error] 5. SLLA053B 6 Performance of LVDS With Different Cables •The line impedance must be 100 Ω ±15% for the bandwidth of 1 MHz up to the maximum frequency applied. This calculator finds both odd and even transmission line impedance, including four different types of impedance used in characterizing differential trace impedances, for microwave antennas, couplers and filters applications. Differential pair routing is one of many aspects of high-speed design. Inputs Trace Thickness Substrate Height Trace Width Trace Spacing Substrate Dielectric Outputs Odd: Ohms Even: Ohms Common: Ohms Differential: Ohms Overview Differential Stripline Impedance Calculator. 3. It is relevant when high-frequency signals are propagating on the PCB transmission lines. 5 (FR-4) ! even for Conductor/Plane layers. Where Z 0 is the characteristic impedance of the asymmetric. Calculating the Differential impedance is a two-step process, first Calculate the single ended impedance Zo and then use this value to calculate the differential impedance. High speed PCBs and signaling standards almost entirely use differential pairs with precise impedance. An online transmission line calculator is a web-based tool that allows users to calculate various parameters associated with transmission lines. The voltage equation can now be written as V L1 = V L0 + V J1. Board thickness (h) = 50 micron. This calculator is designed to calculate the characteristic impedance of a microstrip - a flat conductor suspended over a ground plane with a dielectric between. So move to your left, use Omni's Cable impedance calculator and enjoy. **Note: Like our stripline impedance calculator, all of our RF calculators allow SI prefix input. Coplanar Waveguide Calculator. 1 where k is the solution of: Eq. You only need to know the resistance, the inductance, and the capacitance values connected in series or parallel. Reset. Activate the mixer to its normal operating conditions. WE WANT UNCOUPLED FORM! Pay Attention to UNITS! Wave Equations for Transmission Line Impedance and Shunt Admittance of the line . Ask the board manufacturer for the values. Microstrip Transmission Line Models. Unfortunately Online Calculators are deceiving unless you actually draw the numbers and understand the ratios and tolerance effects. There are a lot of online trace impedance calculators specifically designed for differential traces. PCB Structures / Discrete Structures / Signal Management. Solution of Wave Equations (cont. e. h = Dielectric Thickness. The differential impedance depends upon the D/H ratio. Most online calculators do not account for copper roughness. Broadside Coupled Stripline Transmission Line Models. While there are many 2D field solvers available, many are either bundled inside expensive tools, or have a user interface with a steep learning curve. The cloder the two traces, the smaller is the differential impedance Following is the formula for differential impedance for a Microstrip. A PCB impedance calculation generally refers to the task of calculating trace impedance, or transmission line impedance, based on the stackup and material configuration used in your design. Edit: also, think ahead if you are going to use ground pours around the traces. 4: Normalized even-mode and odd-mode effective. Coax Impedance (Transmission Line) Calculator. 4mils = 0. Ask the board manufacturer for the values. The impedance of a differential via pair cannot be treated with a single via impedance calculator unless the vias are spaced far apart. It renders fairly accurate results suitable for use in circuit board manufacturing and engineering analysis. So, I am trying to figure out how to use Kicad’s PCB Calculator for “Coupled Microstrip Lines”: I’m unsure about what a couple of the parameters mean and can’t find an explanation in the docs (it just. 0 signaling is actually a single-ended signaling but "driven differentially" on major data transfer functions. 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. Twisted pairs are used with balanced signals. Any line condition placing the impedance phasor tip within this circle will cause the relay to trip. Figure 5. 3 Design Formulas for a Stripline. Learn how to configure, define, and use your design’s impedance requirements for single-sided and differential on each layer, with Altium Designer’s Layer St. Here we explore the Cadence PCB Impedance CalculatorCheck here: UltraCAD's new Differential Impedance calculator will calculate single-ended and differential impedance for the common configurations we all deal with: Microstrip. The surface finish is neglected. Your relay is single line with characteristic impedance of 50 Ohms. 1). Single-ended signals are fairly straightforward. For example, a single 0. Impedance (Ω): The desired impedance. Microstrip allows for thinner flexible. Here, Z11 is the characteristic impedance looking into port 1 for one of the transmission lines. Moreover, this tool can also compute the signal propagation delay in inches per nanosecond (ns/in), the inductance per unit length in nano-Henrys per inch (nH/in), and. make the assumption that you will get rid of transmission line effects and calculate based on a lumped-parameter system. Figure 5. Impedance in your traces becomes a critical parameter to consider during stackup. Termination: A long cable can act like a transmission line. The number in the column labeled as polarization refers to the line used for the alignment of this degenerated mode. Microstrip Transmission Line Models. Therefore, for a Zd of 90 ohms a Zo target of 50 ohms is much more realistic. Example, If w = 10 mil, d = 63. 035mm and Er = 4. 2. Figure 1 shows the generic conduction paths of the common-mode and differential-mode noise of a dc-to-dc power supply (the DUT in an EMI lab). Yet I got a ZDiff CPW with ground capable calculator: Differential surface coplanar waveguide with ground calculations: *0. The characteristic impedance and load impedance are used to calculate the input impedance of the terminated line at a particular frequency. The mutual inductance and capacitance exist to give the two pairs an equivalent total inductance and capacitance, respectively. For example, with microstrip, you can specify the substrate parameters (primarily thickness and dielectric constant) and use Linecalc to calculate the impedance for a given line width; this is the “analysis” mode. The range of accepted values is 20 to 90 Ω for single-ended and 50 to 150 Ω for differential signals. , "Characteristic Impedance of the Shielded-Strip Transmission Line," IRE. 1. Single-Ended Impedance. 331 1 2 5. Include both the pcb dielectric thickness as well as the wire insulation in the height calculation. - For the obtained Zo in your Smith Chart calculate the admittance. If the impedance of the load matches that of the source, impedance matching is not required, and the balun has a 1 : 1 impedance ratio. Select the units for all dimensions: mm mils. between the source impedance and the load impedance. Either the desired impedance at a specific frequency is used to determine the waveguide width, or the width is entered and the impedance is calculated. The best differential coplanar waveguide calculator can account for all of these effects simultaneously and without a complex 3D field solver. You must show all your. Embedded Microstrip Impedance Calculator. Then the low-impedance termination resistors, connectingDifferential pairs are very simple: they are composed of two traces, routed side-by-side, and that carry equal magnitude and opposite polarity signals on each trace. Don’t forget to check out our other. g. A commonly-encountered form of parallel wire transmission line is 300 Ω 300 Ω twin-lead. The calculator is available in the Electrical Domain in Constraint Manager, from the Differential signaling in flex circuits follows the design method of surface microstrip transmission lines. 48 e-0. Note that for the terminated case, the gain is measured with respect to the differential voltage at the termination, VIN = VD+ – VD– . Using this calculator, I found 100 Ohms by giving 9 mils of track width, 5 mils of track separation, 8 mils of dielectric (prepregs usually have a dielectric constant of 3. Length of both tracks should be the same. 6 ohms and Z even = 110 ohms for your geometry, very close to your result. ). Hi, I am working on my board Stack-up to tune Single/Differential impedances of my board in Allegro PCB 16. Width (W) Height (H) Calculate. When you use a line calculator with a proper 'diff pair' mode, it will take account of the geometry and the correct driving conditions, and provide you with a pair of lines that has 100 ohms differential impedance, and two lines of 50 ohms impedance when the other line is driven with an inverted signal. The terminationPCIe: From PCI-SIG standards, PCIe Gen1 has 100 Ohms differential impedance, and Gen2 and higher have 85 Ohms differential impedance. The first step is to do a full two-port calibration on the network analyzer. Enter the relative permitivity, width of the trace, the ground plane spacing, and the substrate thickness to calculate the characteristic impedance. It is relevant when high-frequency signals are propagating on the PCB transmission line. THESE FORMULAS ARE APPROXIMATIONS! They should not be used when a high degree of accuracy is required. 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. Standard 4-Layer Stackup. Z diff = 2* Z o (1 - 0. Simons, "Coplanar Waveguide Circuits, Components, and Systems", Wiley. For coupled surface microstrip, Wadell[1] gives 7 pages of equations to evaluate the impedance. This assumes ~0 trace thickness. This calculator assumes. 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. The generator and load impedances are G and ZL, respectively. The differential- and common-mode parameters of coupled lines can be derived from the odd- and even-mode parameters. L is the inductance in henries (H),. Thus a "differential pair" any long distance apart will have an impedance of 98 ohms, without any coupling between the lines, i. The amplitude increases as the coupling length increases up to a point. A transmission line always features a differential microstrip impedance. You will see the Differential Impedance Calculator interface with input fields for Characteristic Impedance (Z0) and Common Mode Impedance (Zc). Dimensional units: mm mils. That's why the numbers Mikrocontroller. 2. 5. When considering differential traces, add the space between traces (s) to this list. The IPC-2141 trace Impedance calculator will help make initial design easier by allowing the user to input basic parameters and get a. This is an important parameter in the analysis and design of circuits and systems using transmission lines. Trace spacing (S) mils: Distance between planes (B) mils: Relative Dielectric constant (Er) Differential Trace Impedance: ohms: References. Differential Impedance Ω. I use FR-4, so H=1. Characteristic impedance is purely a function of the capacitance and. For now let us focus on the single ended impedance. When designing the trace configuration for your differential pairs, you are typically targeting 100 ohms differential. eu. Spacing and width value pairs that will give a differential impedance of 100 Ohms on Dk = 4. With high speed and high frequency controlled impedance design, you need design tools that allow you to define the proper impedance for your specific trace configuration on surface layers or on internal signal layers. Backwards crosstalk creates a pulse width that is twice that of the propagation time of the pulse traveling the coupling distance. Loss is calculated as a combination of dielectric loss and conductor loss at the analyzed/synthesized length. During a data transmission, the differential line voltage of a fully loaded bus is required to be higher than ±1. High speed measurement tools. Enter values for W and L for a microstrip line to determine its Zo and Electrical Length. The input impedance, RIN, is equal to 2RG1 for a balanced differential drive. The impedance Z 0 of a transmission line consisting of a circular signal conductor having a diameter d and centered between parallel ground planes separated by a distance h is given by: Eq. The required values are trace thickness, substrate heights, trace width, and subtrate dielectric in the calculator above and press the "calculate" button. The following are typical line widths and spacings for the more common impedance values when using ½ OZ copper: 50 Ohm Single Ended: 0. The technique sends the same electrical signal as a differential pair of signals, each in its own conductor. A coupled line will have characteristic impedances for both common (ZC) and differential (ZD) mode. Differential pair on a reference plane for differential mode (left picture) and common mode (right picture) line impedance In addition to the four line impedance types the Impedance Calculator is also able to calculate the Coupling Factor between two traces on either the same signal layer (horizontal coupling) or between two traces on different. The specifications of my PCB are- the conductor thickness is 2oz(2. ; Z 0 is the characteristic impedance of free space (approximately 377 ohms). 96D/H) Zo. Imagine a differential pair made of two individually screened 50 ohm cables. Odd mode impedance is defined as impedance of a single transmission line when the two lines in a pair are driven differentially (with signals of the same amplitude and. Differential impedance is the ratio of voltage to current on a pair of transmission lines when driven in the differential mode (one signal positive and the other negative). , the structure is made up of two dielectric materials: air and the substrate material). The JLCPCB Impedance Calculator computes track width values and recommended stack-ups from user-input values of board layer, thickness, copper weight, target impedance, trace spacing (for edge-coupled pairs), and impedance trace to copper gap (coplanar waveguides). 1< W/H < 3. If the transfer impedance is known, then you can calculate the differential impedances from single-ended measurements. In some cases, we can also use 75-ohm differential. You can calculate it with the following equation: Z (z) = V (z)/I (z). Also note that your best bet may actually be VERY SHORT (few mm) traces, a thinner board or a 4 layer board :-) Thanks for your suggestions. This circuit only filters differential signals; if there is an in-phase signal (or interference) on both lines (called a common-mode signal/noise) it provides no filtering to it. Determining trace impedance and propagation delay in PCB traces takes a trace length calculator and impedance profiler tool, and these features work best when they are integrated into your PCB design software. There are single end trace impedance and distance between traces in the pair. Also, keep impedance variations as small as possible. On a reference plane, there is an edge coupled differential microstrip line with two traces. We care about maintaining the same differential impedance for the. With the expressions for VO± from before and some algebra, an equation to calculate the output impedance of the circuitTo change the low-pass filter into a band-pass filter, add two shunt inductors: L7 in parallel with C9 and L8 in parallel with C11. 9. Thinking about the problem as the impedance the differential signal sees (the thing we care about) compared to the impedance the common mode signal sees (the part of the signal we typically try to eliminate in a difference amplifier) is probably more appropriate for most practical signals, and gives us a nice simple expression. For sample: 45-46 Ohm single end traces impedance can be used in diff. 1 (a). *The structure may propagate in 3 modes: coplanar waveguide, coupled slot lines and microstrip. Given the defaults (1. Press Analyze to see the results. Agilent's LineCalc tool calculates Z odd = 50. 6 Ω and ε e = 6. Or the odd mode impedance is half of the differential impedance. 1. 5mm, T=0. To calculate the external resistor values, start by calculating Z IN. (Not reasonable in general, but sometimes used for test and measurement purposes). Relative Dielectric Constant ( εr ): Track Width (S): mm. The free version allows calculation of simple single-ended and differential microstrip and stripline structures. The K values for the various transmission lines are also copied from his Transmission Line Details windows software. Track width (w) = 137 micron. This calculator allows you to add the impedance model and compute the desired trace geometry and spacing for a target impedance. Differential Stripline Impedance Calculator. 3mm, as shown below: This increases the impedance slightly to 91. 3. W/H. If it is different, you need to increase the length of shorter track to match with the longer track. Stripline. Calculating Width and Spacing Comparing Width and Spacing for Differential Microstrips The concept and implementation of differential impedance are. Imagine a differential pair made of two individually screened 50 ohm cables. However, during a handover of bus access from one node to another, or during a transmission pause, the bus idles. , 10. 3: Normalized characteristic impedance and normalized effective permittivity of a microstrip line as a function of u = w / h. ε R. Impedance Calculators used by Mantaro engineers and provided here for your use freely. You can use all the calculators you want if you don't know the exact board make up they're using; they should be able to help you. The impedance calculator in the Layer Stack Manager supports single and differential coplanar structures. w = Trace Width. 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. 6 Coaxial Line The analytic calculation of the characteristic impedance of a transmission line from geometry is not always possible except for a few regular geometries (matching orthogonal coordinate. 0; 1 < ε r < 15 ) Select the units for all dimensions: mm mils. Select the box with the geometry that you would like to calculate. Microstrip construction consists of a. Following is the formula for differential impedance for a Stripline. There are four different types of impedance used in characterizing differential trace impedances. The odd mode impedance, Z 0,o, is given by the following equation: Eq. 5 and I took 3. 100 Ohm Differential Pair: 0. Coaxial Line Impedance Calculator. Enter values for W and L for a microstrip line to determine its Zo and Electrical Length. Dear all, I have simulated a differential pair lines (GSSG). PCB Impedance-Calculation: Help with the dimensioning of the impedances of your circuit board. Notes:. Slot Line Calculator. Most RF Coaxial Cables have an impedance of 50 ohms or 75 ohms. the impedance seen from the line with this architecture; the diagram is shown in Figure 5. The pair of conductors can be wires in a twisted-pair. If trace width is increased for the metal losses reduction, the single end impedance will be reduces. The only requirement is the required attenuation in decibels (dB) and the impedance in ohms. Characteristic impedance is the ratio of voltage to current for a wave that is propagating in single direction on a transmission line. Safe connection of measuring equipment 4. A signal transmitted differentially. Just enter the given values for trace thickness, substrate heights, trace width, and substrate dielectric. Stripline. One of the features of this type of microstrip is the coupling betwe…Differential Stripline Impedance Calculator. Microstrip line is a widely used transmission line and for the appropriate transmission its characteristic impedance has to be calculated while using it in RF design & circuits. Differential Microstrip Impedance From Zo. The trace impedance (single-ended) in an individual trace is normally calculated by ignoring any neighboring traces, so no coupling to other conductors in the design will be. The plots show the magnitude and phase of the input impedance. A differential stripline pair refers to two traces located between two reference plane layers, which are routed as a differential pair. (Differential Impedance, Ohms) = Note: 1oz = 1. Coaxial Line Impedance Calculator. Skin Depth Calculator. 6. Actually the "odd impedance" is the correct impedance to look at for the USB requirement of 90 Ohms differential impedance. First, let’s use the “analyze” approach. To calculate the differential impedance of a microstrip, divide the characteristic impedance of the microstrip by 2. The odd mode impedance, Z 0,o, is given by the. Given a value for impedance, it will (in most cases) calculate. PCB stackup, signal integrity and controlled impedance: Signal integrity tools: Stackup design. g. The even mode impedance is measured across one line while an equivalent signal drives the other line. When dealing with differential pairs, thi. The top surface and the sides of the traces are exposed to air and are referenced to a power or ground plane. This figure shows that the differential output equals 2 × R P in parallel with the effective value of R′O = 2(VOUT± FO – VO±)/IO±. D = Separation between the differential traces. FWIW, the calculator. This calculator is designed to calculate the characteristic impedance of a broadside couple stripline (see diagram below). The microstrip calculator determines the width and length of a microstrip line for a. EXAMPLE: INPUTS: Er = 4. These parameters include: Characteristic impedance (Z 0): The online calculator can compute the characteristic impedance of a transmission line, which is the ratio of voltage to current in a. Calculate Coplanar impedance for given PCB parameters. 0075” spacing. Common Mode Impedance (Zc) is the impedance when signals. 0 and (t/h) less than 0. The stripline impedance calculator provided below is useful for gaining an initial estimate of trace impedance for striplines. For an embedded (internal) microstrip, the formulas provided in paragraph 4.