Rogers Advanced Connectivity Solutions (ACS) has introduced an updated design program that is free to download called the MWI-2017 Microwave Impedance Calculator, a transmission line modeling tool for electronics engineers (setting up an account is required).

The MWI-2017 Microwave Impedance Calculator software doesn’t replace sophisticated suites of modeling tools, such as the Advanced Design System (ADS) from Agilent Technologies or Microwave Office from AWR. Nor can it challenge the prediction capabilities of a planar or 3D electromagnetic (EM) simulator such as HFSS from Ansys or the Sonnet suites from Sonnet Software. But what it does, it does well, which is to calculate key parameters for most common microwave transmission lines, including microstrip, stripline, and coplanar-waveguide transmission lines. The software is downloaded as an executable (.exe) file and runs on most Windows-based personal computers, including those with Windows XP, Windows 7 and Windows 10 operating systems. To speed and simplify the use of the software, Rogers also offers a 22-page operator’s manual in PDF file format.

MWI Microwave Impedance Calculator


Using the Transmission-Line Modeling Tool

 The MWI-2017 program is based on closed-form equations derived from Poisson’s wave equations. The simple-to-use software can determine key parameters for a selected transmission-line type and laminate material, such as the conductor width and conductor metal thickness needed to achieve given impedance at a target frequency. The software’s intuitive graphical user interface (GUI) screen allows a user to select from a variety of different transmission-line types, including conventional microstrip, edge-coupled microstrip, conventional stripline, offset stripline, and conductor-backed coplanar-waveguide (CPCPW) transmission lines. The on-screen menus allow a user to select a transmission-line technology and a laminate material. Once a material, such as Rogers RO3003™ material, is selected, its pertinent characteristics are also shown on the screen, including relative dielectric constant (permittivity), dissipation factor (loss), thermal conductivity, and thermal coefficient of dielectric constant. Moving a mouse cursor over any material name reveals additional information about the material.

Enter Parameters such as Thickness, Operating Frequency and RF Power Level

With a material in place, the next step is to pick a standard dielectric thickness from a menu, or enter a custom thickness. A standard copper cladding thickness must also be selected from a menu, or a custom thickness entered manually. Copper conductor roughness is also accounted for, either selected from a menu as a standard value, or entered manually as a nonstandard value. Similarly, a standard value for copper conductivity can be used in a calculation, or a custom value entered, although any change in the value for copper conductivity will affect all metal layers in a multilayer circuit.

The MWI-2017 software allows an operator to enter parameters pertinent to a specific application, such as operating frequency and RF power level. Once a user has selected the desired transmission-line type, dielectric material, material thickness, conductor width, thickness of the conductive metal cladding, etc., a calculation will provide results in terms of such transmission-line parameters as conductor width and conductor spacing for a selected impedance. The software can generate insertion loss tables of data that can be used to create plots of loss versus frequency, and these plots can then be compared to actual measured results from a microwave vector network analyzer (VNA).

This exact procedure was performed to evaluate the accuracy of the MWI-2017 software for calculations of conventional microstrip parameters. MWI-2017 calculations performed for conventional microstrip transmission lines have proven to be extremely accurate since they include the effects of dispersion as well as copper roughness. For example, calculations performed on RO3003™ laminates have compared quite closely with actual measurements. These are ceramic-filled PTFE composite materials with a dielectric constant of 3.0 at 10 GHz and dissipation factor of 0.0010 at 10 GHz. In a comparison of MWI-2017 predictions versus measurements for a 5-mil-thick microstrip transmission line on RO3003 laminate with 1/2-oz. ED copper cladding, predicted and measured data matched almost exactly through 110 GHz.

Microstrip Insertion Loss Graph

The MWI-2017 software may not be able to match the accuracy of an EM simulator for a given prediction, but it is considerably faster, providing results almost instantaneously. It has been found to be most accurate for calculations on conventional microstrip and stripline, very accurate with edge-coupled microstrip and offset stripline transmission lines, and fairly accurate with conductor-backed coplanar-waveguide (CBCPW) transmission lines, although in the case of CBCPW transmission lines, vias must be properly placed to ensure accurate results.

Stripline insertion loss graph

Calculating the impedance of transmission lines is not trivial, since a number of factors can affect impedance. In microstrip, the width of the conductor and thickness of the dielectric substrate impact impedance. In CBCPW, not only the conductor width and dielectric thickness, but the spacing on the signal plane between the signal conductor and the adjacent ground planes will affect impedance. The MWI-2017 software is free, and provides results fairly quickly that are accurate and can be saved for use in other programs, including in word processors or in spreadsheets for creating x-y plots. In addition to calculating the impedance and loss of a transmission line, the MWI-2017 software provides information on a laminate’s effective dielectric constant, signal wavelength, skin depth, the electric length for a transmission line at a selected frequency, and propagation delay. It can even calculate the temperature rise above ambient temperature for a selected laminate based on an input RF power level.

For anyone needing a quick impedance calculation for designing a filter, coupler, or other high-frequency circuit, the MWI-2017 software provides usable results. And the price is right!

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We are pleased to announce that Rogers Corporation has signed a definitive agreement to acquire Arlon, LLC, currently owned by Handy & Harman Ltd. (NASDAQ: HNH), for $157 million, subject to closing and post-closing adjustments. The transaction, which is subject to regulatory clearances, is expected to close in the first half of 2015. Rogers intends to finance the transaction through a combination of cash and borrowings under an existing bank credit facility.

RogersCorporation logoBruce Hoechner, President and Chief Executive Officer of Rogers said, “This transaction is truly a unique strategic fit for both Rogers and Arlon. We are energized by the opportunity to serve our customers with our complementary capabilities and technologies in circuit materials and engineered silicones and to enhance value for our shareholders. We look forward to closing this acquisition as another significant milestone in Rogers’ growth as a premier global engineered materials solutions company.”

arlon_logoArlon: A Strong, Strategic Fit

The proposed acquisition of Arlon is consistent with Rogers’ strategy as it adds complementary solutions to its Printed Circuit Materials and High Performance Foams business segments and expands Rogers’ capabilities to serve a broader range of markets and application areas.

Arlon’s circuit materials product family positions Rogers for additional growth in the rapidly expanding telecommunications infrastructure sector, as well as in the automotive, aerospace and defense sectors. Arlon produces its circuit materials in Bear, Delaware; Rancho Cucamonga, California; and Suzhou, China.

The engineered silicones product family of Arlon will further diversify the Company’s solutions and market opportunities in sealing and insulation applications. Arlon will bring new capabilities in precision-calendered silicones, silicone-coated fabrics and specialty extruded silicone tapes. Used primarily for electrical insulation, these materials serve a wide range of high reliability applications across many market segments, including aviation, rail, power generation, semiconductor, foodservice, medical and general industrial. This product family is primarily manufactured in Bear, Delaware.

Revenue and operating income for the Arlon segment of Handy & Harman Ltd. were $100.4 million and $16.7 million, respectively, for the trailing twelve months ended September 30, 2014 (compiled based on amounts reported by Handy & Harman Ltd. in Forms 10-K and 10-Q filed with the Securities and Exchange Commission).

Press Release: Rogers Corporation Signs Definitive Agreement to Acquire Arlon, LLC

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Congratulations to the ROG Blog team on their 50th post! This post authored by John Coonrod originally appeared on the ROG Blog hosted by Microwave Journal.

This ROG Blog series on printed-circuit-board (PCB) materials has reached the half-century mark, already covering a wide range of topics on circuit materials with this, the 50th ROG Blog. For example, this series has recommended materials for amplifiers, for antennas, for filters, and for different types of transmission lines. It has even detailed the effects of different PCB material thicknesses on circuit performance, and described the influence of conductor roughness on circuit performance.

While it would be difficult to pick out the top 10 Blogs from the first 49 Blogs appearing since August 2010, at least 10 of these ROG Blogs deserve mention for how they have attempted to help readers with their different uses of PCB materials.

From the very first ROG Blog, in August 2010, which compared low-cost FR-4 circuit substrates with higher-frequency PCB materials such as the Rogers substrates, to the latest ROG Blogs, which examine circuit material requirements for emerging millimeter-wave wireless applications through 300 GHz and higher, the ROG Blogs have attempted to provide clear and honest information on the use of circuit materials. The next 50 ROG Blogs will pursue the same ambitious goals, in hopes of providing readers with greater benefits for their uses of high-performance circuit materials.

While it would be difficult to name the “Top Ten” ROG Blogs from the series so far (see the list below), it is not surprising to find that one of the most popular (in terms of viewers/readers) would be one that also refers to something for free: the January 2011 ROG Blog on Rogers’ free transmission-line modeling tool, the MWI-2010 Microwave Impedance Calculator. This easy-to-use modeling tool, which has also been reviewed in many of the leading RF/microwave trade publications, calculates key parameters for most common microwave transmission lines, including microstrip, stripline, and coplanar-waveguide transmission lines. The executable (.exe) file is available for free download from the Rogers’ website and runs on Windows-based personal computers (PCs), including those with Windows XP, Windows Vista, and Windows 7 operating systems. The free software is even backed by a 22-page operator’s manual in PDF file format, also available for free from the Rogers website.

In many ways, the ROG Blog series is like a book on circuit materials, unfolding online before its readers, with each Blog adding a new chapter to the book. Each chapter shares what Rogers’ engineers have learned over the years about making and using circuit materials, and this first set of 50 Blogs has covered some areas of interest to a large number of readers. In line with the ROG Blog on free software, the ROG Blog “Comparing RF Circuit Material Processing Costs & Performance” also offers advice meant to help readers save money without sacrificing their performance goals. Although first appearing on “April Fool’s Day” (April 1) in 2011, this ROG Blog takes a serious look at the total costs of circuit materials, and how some circuit materials may have lower material costs than other materials, but pay for it later with higher processing costs and lower yields. It also explains how some performance parameters, such as passive intermodulation (PIM) in wireless circuits and signal integrity in digital circuits, require a careful consideration of tradeoffs in material and processing costs when choosing a circuit material.

These first 50 ROG Blogs have drawn readers for familiar themes as well as for some not-so-familiar topics. For example, the ROG Blog appearing on November 19, 2010, “What Is Outgassing and When Does It Matter,” addresses a subject that may be unknown to some readers but quite significant to others. Outgassing, which refers to the release of gas inside a solid such as a circuit material, especially when it is placed in a vacuum, can greatly impact the performance of circuits used in satellite-communications systems in space, or in medical electronics systems. This ROG Blog introduced many readers to a material term known as total mass loss (TML), and how the parameter could be used to help guide the selection of a circuit material for space-based or other applications where outgassing was a critical concern.

On the other hand, some of the more popular ROG Blogs covered the roles that circuit materials play in the design of some basic RF/microwave components, such as amplifiers, couplers, and filters, and how the choice of a circuit material can affect transmission-line losses in high-frequency circuits. One of the more popular ROG Blogs, “When Digital Signals Reach Microwave Frequencies,” covered an area of  interest to many microwave circuit designers, how to deal with digital circuits operating at microwave frequencies. This ROG Blog, appearing on February 23, 2011, reviews some of the important concerns for selecting a circuit material when circuits cross over from the digital area into the microwave realm. These high-speed digital signals will behave much like analog microwave signals, affected by PCB loss and even conductor surface roughness. To guide those in need of circuit materials for high-speed digital designs or even multilayer circuits that may combine fast digital and microwave circuits, this ROG Blog points out how different circuit material characteristics, such as dielectric constant and even coefficient of thermal expansion (CTE), can impact high-speed digital circuit performance.

At times, readers of the ROG Blog series shared their areas of interest and applications for circuit materials, and these applications are many and diverse, from lower-frequency analog and power circuits to high-speed digital and even microwave/millimeter-wave circuits. The ROG Blog series is written to serve its readers with new information on circuit materials as that information is needed, much like new chapters to an on-going, online book about circuit materials. Do you have a suggestion for future ROG blogs? We’d love to get your input. Let us know what you are interested in reading about.

Top 10 Popular ROG Blogs (based on reader feedback)

  1. Transmission-Line Modeling Tool: Free Downloadable Software” (1/27/11)
  2. What Is Outgassing And When Does It Matter” (11/19/10)
  3. Comparing RF Circuit Material Processing Costs & Performance” (4/1/11)
  4. Controlling Conductor Losses In Coplanar Transmission Lines” (3/14/11)
  5. When Digital Signals Reach Microwave Frequencies” (2/23/11)
  6. Do You Have An Award Winning Application?” (11/11/11)
  7. The Role of PCB Materials In Impedance Matching” (12/3/12)
  8. Choose Circuit Materials For Bandpass Filters” (1/16/13)
  9. Make Waveguide In Planar PCB Form” (10/18/12)
  10. Celebrating ROG Award Contest Winners at IMS 2012” (7/17/12)

Do you have a design or fabrication question? John Coonrod and Joe Davis are available to help. Log in to the Rogers Technology Support Hub and “Ask an Engineer” today.

At the IPC Conference in February, John Coonrod sat down with Mark Thompson, Guest Editor at I-Connect007 to talk about thermal management scenarios that have come up through various customer situations.

“A circuit is heating up more than it should, why”?

By digging into the details, John identified several scenarios and wrote about them in a paper and presented this paper at IPC.  A couple scenarios include:

  • Thermal heat being generated  not due to power going through the circuit but because a hot chip is sitting on the circuit
  • RF power heating the trace and going through the circuit

Watch the video on Rogers’ Technology Support Hub (below) to hear more or download the paper/presentation John gave at IPC (requires registration):

Already a member of the Technology Support Hub, click here

Become a member of the Technology Support Hub, click here


This post authored by John Coonrod originally appeared on the ROG Blog hosted by Microwave Journal.

The use of circuit defects is a growing trend in high-frequency circuit design

Successful microstrip circuit design requires a great many factors to fall neatly into place, not to mention high consistency and performance from the printed-circuit-board (PCB) material. Maintaining tight microstrip circuit tolerances helps ensure predictable impedances from those transmission lines, assuming a consistent relative dielectric constant across the PCB. With so many challenges in designing and fabricating high-performance microstrip circuits, why would so many RF and microwave circuit designers currently be interested in adding “defects” to their circuits? As strange as it may sound, the use of circuit defects is a growing trend in high-frequency circuit design, especially for passive circuits such as filters. More precisely, the trend is in the increased use of defected ground structures (DGSs) and defected microstrip structures (DMSs) to alter the responses of microstrip circuit designs.

What are DGS and DMS forms?

Just what are these DGS and DMS forms, and does incorporating them into a high-frequency circuit change the way the PCB material should be specified? Although both types of structures are referred to as “defects,” they are well planned and calculated, essentially resonant gaps or slots that are placed in a PCB’s ground plane or transmission lines, respectively, to achieve modifications in impedance. By inserting a gap in the ground plane underneath a narrow microstrip transmission line, for example, a much higher impedance can be achieved than with a traditional microstrip transmission line having the same dimensions. Impedance transitions are useful in a number of different RF/microwave circuit designs, including lowpass filters which can be formed with a cascade of high- and low-impedance sections.

A DGS allows a circuit designer to insert a transmission zero or notch anywhere in the transfer function of a microstrip transmission line. This type of added attenuation can sharpen the rolloff of a bandpass filter or deepen the stopband attenuation of a lowpass filter. Designers have employed this phenomenon in both active and passive circuits. In active circuits, DGS circuit elements have helped improve the efficiency of power amplifiers. In passive circuits, they are often used to fine-tune a filter’s response or improve the performance of a patch antenna. Even simple DGS and DMS forms can help extend a filter’s stopband by adding attenuation at the resonant frequencies represented by the physical gaps in the PCB’s ground plane or microstrip transmission lines. In recent years, designers have become quite creative in exploring the possibilities of DGS and DMS forms and shapes in high-frequency circuits, eschewing simple slots or gaps in a ground plane, for example, for dumb-bell shapes and meander lines in an attempt to achieve higher-impedance transitions in smaller PCB areas.

DGS and DMS circuit elements must be treated with care

As part of distributed circuit design, DGS and DMS forms are treated as distributed circuit elements, more or less as inductors. They can replace a conventional distributed transmission-line inductor while possibly minimizing circuit loss. In terms of practical PCB fabrication, however, DGS and DMS circuit elements must be treated with care. While they can be used to add selective notches in a circuit’s frequency response, they will not improve passband insertion loss, which will largely be a function of the PCB’s material parameters and the transmission-line characteristics. The best way to achieve low passband insertion loss in a filter is still by choosing a low-loss laminate, such as RO4000® or RO3000® circuit materials, which are available with a wide range of dielectric constants and dissipation factors as low as 0.0013 at 10 GHz. In addition, by using circuit materials with a high relative dielectric constant, such as RO3010™  or RT/duroid® 6010.2LM laminates, both with dielectric-constant value of 10.2 at 10 GHz, the benefits of DGS and DMS circuit elements can be readily applied to edge-coupled filter designs.

DGS and DMS circuit elements can increase the size of a circuit, especially when these structures are fabricated as more element forms, such as meander lines. A DGS essentially acts like a resonant circuit in parallel with the transmission line above it, and the dimensions of the DGS and its position relative to the transmission line will determine the impact of the DGS on the circuit’s response. The precision with which the DGS or DMS form can be fabricated can also affect the circuit’s response. If the DGS is thought of as an equivalent circuit element, such as an inductor, in a distributed circuit design, then the value of that inductor will change according to the dimensional tolerances of the DGS and its alignment to the transmission line. Even the consistency of the PCB’s dielectric constant can play a role in the inductance of a DGS within a circuit. When applying these types of “defects” to a high-frequency circuit, they should be designed well within microstrip fabrication tolerances and taking into account the consistency of the PCB material’s relative dielectric constant.

How do you integrate DGS and DMS into practical RF/microwave circuit designs?

If DGS and DMS circuit elements are so finicky, how is it possible to integrate them into practical RF/microwave circuit designs? For the most part, both types of structures are modeled by means of electromagnetic (EM) simulation software, based on a number of different analytical methods, such as the method of moments (MoM) or the finite-element method (FEM). Through EM simulation, it is possible to estimate the effects of DGS and DMS placement, dimensional tolerances, and even how using circuit laminates with different values of permittivity affect expected performance. However, it is only fair to note that DGS elements can act as radiators as well as resonators. A slot in a laminate’s ground plane essentially forms a slot antenna. Fortunately, most of the incident energy of a DGS slot at its resonant frequency is reflected back into the circuit’s transmission lines, although depending upon the circuit topology, some of this energy can be coupled into different circuit features. Such coupling effects are difficult to model in a practical EM simulation.

This post has only touched upon some of the unconventional structures being used by RF/microwave circuit designers in search of improved performance at higher frequencies. A future post by John will return to this topic with a closer look at some of the other stripline and microstrip circuit structures that are finding application in high-frequency circuits, including torroidal inductor structures using holes in the ground plane, substrate integrated waveguide (SIW), and split-ring resonators as used in terahertz-frequency metamaterials. And for those involved in automotive electronics, John’s next post will explore the role of PCB materials in helping automotive manufacturers meet their performance and cost budgets for automotive electronic systems.

Do you have a design or fabrication question? John Coonrod and Joe Davis are available to help. Log in to the Rogers Technology Support Hub and “Ask an Engineer” today.

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