Tuesday, January 23, 2018

CST Filter Design Technology: a Powerful Toolkit for Microwave Engineers


In recent years, CST's filter design and analysis technology have continually improved, resulting in exciting new tools that facilitate design, analysis, and optimization. We spoke to one of CST’s resident filter experts, Dr. Theunis Beukman about the latest solvers and features that make CST STUDIO SUITE® such an excellent tool for designers.

If you want to learn more, our Filter Design Workshop is fast approaching and registration is open! The workshop will take place on February 27th outside Washington D.C. and will no doubt benefit filter designers of all levels and areas of focus. We also recommend checking out our 2017 eSeminar, "Overview of CST Filter Design Technology" you can watch on-demand.

What new features for filter design and tuning has CST recently introduced?
Fields in a multimode cavity filter
simulated in CST STUDIO SUITE® 

Over the past two years, in particular, we introduced many new features for filter design and tuning. A vital contribution in this regard came with CST Filter Designer 3D. This tool provides the capability for synthesizing a coupling matrix based on the user’s input of specifications –including arbitrarily placed transmission zeros for bandpass, bandstop or diplexer filters. CST Filter Designer 3D is much more than just a synthesis tool. It also has a unique feature that allows you to extract the coupling matrix from the S-parameters of your EM simulation model, which provides insight into the operation of this 3D model without having to dissect or analyze it using surrogate circuits. Another great feature is our moving mesh technology that helps overcome “mesh noise,” which is a common simulation issue. Moving mesh enables us to tune up very sensitive filters that can have fractional bandwidths of 1% and below.

How does CST’s new coupling matrix based optimization improve the filter design 
workflow?

I think any person who has tried to tune up a filter knows the cumbersome workflow and time-consuming routines they have to endure (perhaps with a minimal number of exceptions). What we’ve done is taken the new capabilities of CST Filter Designer 3D and implemented an optimizer dedicated for coupled-resonator filters. Our software eliminates that time-consuming effort when tuning and provides an efficient solution that is far more capable than brute-force optimization.

Besides EM, what multiphysics effects do filter designers also need to watch out for?

When it comes to transmitter systems, front-end filters typically need to be able to handle high input power. This can lead to various unwanted effects that require advanced simulation during the design phase. A very capable tool in our arsenal is SPARK3D, which uses advanced algorithms to calculate possible RF breakdown either in a vacuum or in gas – perhaps better known as multipaction and corona discharge. Another potentially harmful effect is heating due to power dissipation in a device or adjacent components. This can lead to substantial detuning of the filter structure and therefore requires both thermal and mechanical simulation which are available in CST STUDIO SUITE® 2018. At the workshop, we will have two dedicated sessions for these topics.

Speaking of the workshop, could you give us an overview of what will be covered? Who should be sure to attend and why?

This workshop is a fantastic resource for all filter designers, regardless of whether you are currently using CST STUDIO SUITE® or you’re just curious about the topic of filter simulation. This workshop will provide you with a solid overview of the complete set of simulation solutions that can be applied in practical filter design.

The program will include topics like synthesis, the realization of distributed models, tuning based on the coupling matrix and multiphysics analyses. There will be a focus on bandpass filter design, though we will also touch on other types such as lowpass/highpass and multiplexer filters. We will showcase the different tools that are applicable in each stage of the design workflow and highlight the underlying technologies that make it possible.

Register here for the CST Filter Design Workshop.


Dr. Theunis Beukman is an application engineer at CST - Computer Simulation Technology in Darmstadt, Germany. He received his MScEng (cum laude) and Ph.D. degrees in Electrical and Electronic Engineering from the University of Stellenbosch, South Africa, in 2011 and 2015 respectively. During his Masters, Dr. Beukman worked on tunable wideband filters for the Square Kilometre Array (SKA) project and spent several months as a visiting researcher with the filter group at Heriot-Watt University.

Friday, January 19, 2018

Top 5 Webinars of 2017



Webinars are one of our most popular content mediums, every year CST presents two webinar series' and many individual webinars on hot topics from across the industries that we serve. We crunched the numbers, and these webinars were the most watched this year. They represent some of the most innovative new technologies from CubeSats to wireless charging.

1. Automotive Radar Simulation

This webinar shows how CST STUDIO SUITE can be used to perform and study all of the design stages of automotive radars, starting from the basic element which is the antenna, through its integration inside a radome, to actually placing and calibrating the whole package inside the car, using CST Complete Technology’s versatility and solver diversity.

2. Cubesat Antenna Design

This webinar reviews modern trends of antennas on small satellites. It presents a basic design scenario and how software tools such as Antenna Magus and CST STUDIO SUITE can be used to
address the challenges it presents.

3. Inductive Wireless Charging for Automotive Applications

This webinar focuses on workflows and best practices to predict the performance of individual coils as well as inductively coupled systems in the automotive environment. In particular, the accurate loss prediction in litz wires and ferrite materials is of great importance is discussed in detail. 

4. CST STUDIO SUITE 2018 Technology Highlights

The CST STUDIO SUITE 2018 release contains many new features and improvements for solving Maxwell’s equations and related problems. This webinar highlights some of the best of those improvements and new features, including classical EM-simulations, workflows, multiphysics, coupled simulations, among many others.

5. Antenna Design for a Home Multimedia Device 

This webinar covers the simulation techniques and tools that allow new antenna concepts for Internet of Things devices to be developed and tested quickly at a very early design stage, leading to a better connected device and a reduced overall device design time.

We look forward to another year of great webinars as we at CST explore and explain the latest technological advancements through electromagnetic simulation. Keep an eye out for the "Getting Ahead With..." our tutorial-style webinar series which will be announced soon.

Wednesday, January 10, 2018

Top 5 CST Articles of 2017


Every year, thousands of visitors check out the technical content in CST's large library. With articles and webinars that cover all of the markets and industries that we serve, it's always fascinating to see what was most interesting to our followers.

1. A Dielectric Lens Antenna with Enhanced Aperture Efficiency for Industrial Radar Application 

One application of RADAR (RAdio Detection And Ranging) is to measure the distance to a moving or fixed object using an electromagnetic wave. The distance of the object is determined by the time difference between the transmitted and reflected wave. This article describes such a distance measurement using a RADAR system for measuring the tank filling level in an industrial storage tank.


2. Microstrip Patch Array Design


This article explains the design process for a planar microstrip patch array for WLAN frequencies using the circuit and full-wave 3D solvers and optimization tools in CST STUDIO SUITE®. 

3. Five-Section Microstrip Hairpin-Filter


This practical article covers the step-by-step simulation of a Five-Section Microstrip Hairpin-Filter.

4. Optimization of Torque in a Permanent Magnet Synchronous Motor (PMSM) for Traction Applications

This article summarizes the simulation and optimization of a 200 Hz, 8-Pole Permanent Magnet Synchronous Motor (PMSM) typically used for traction applications in automotive and transportation systems.


5. RFID Reader-Coil, 13.56 MHz


This article details the simulation of a specific  RFID Reader-Coil using CST's frequency domain solver. 

Mesh details of the tetrahedral Mesh used for the Frequency-Domain Solver in CST MWS. 

Tuesday, January 2, 2018

CST Lab: Improving Design with Measurement and Simulation


“Why don’t my simulation results agree with the measurement?” This is the question I sometimes heard from our customers and which inspired us to start CST Lab, which is a project that promotes the combination of simulation and measurement to fix the perennial problem of mismatched results. CST Lab was officially started two years ago, and for the past 5 years we have been working in this space through our joint workshops with Rohde & Schwarz, one of the global leaders in measurement instruments and techniques. These workshops were very well received since the content went well beyond a typical product presentation. The workshops examine critical points in the design process and include hands-on learning for both measurement and simulation portions.
Recently, we introduced a two-day vector network analyzer (VNA) training course, which covers the fundamentals of microwave measurement and the obtained measured data are used during the second day for the material characterization and component modeling.

Providing customers with comprehensive technical support

CST Lab’s objective is to provide our customers with broader, application-based technical support where we deal with the overall design process instead of limiting the support to the simulation portion only.  
CST Lab at European Microwave Week 2017
CST Lab supports our customers who can benefit from our extensive knowledge concerning measurement and its interpretation. The approach is beneficial to all engineers who need to reduce the length of the design cycle making the design process more robust and reliable.  

Benefits of combining simulation and measurement

There are many benefits of combining simulation and measurement during the design stage. Each of the domains is suitable for different tasks. For instance, simulation allows us to do what-if analysis without the expensive and lengthy manufacturing process. We can employ an automatic optimization engine to improve the device parameters. Also, simulation provides an inside view of EM field visualization, which provides a better understanding of the physical mechanisms.
On the other hand, material properties, which are the critical input information for 3D EM simulation, need to be determined using the measurement of a simple, well-defined sample. Measurement is usually very fast, providing the results in real-time. Also, the measurement contains all the physical effects of the device under test (DUT).  So if we combine both domains, we can always be sure we have used the best-suited tool for the particular task.

Common misconceptions

There are a few common misconceptions or mistakes that we encounter and correct when we are working with users or giving workshops on simulation and measurement. The most common mistake is that people simulate something different than what is measured. A typical case is a microwave circuit or antenna that includes an adapter is measured, but because the engineer assumes the adapter behaves ideally, it is not included in the 3D model. However, if we look closer and measure its S-parameters, the results show that the troublemaker is in fact, the adapter. The adapter in this example can be replaced with any other piece of structure that is present in the experiment, but it is missing in the virtual model. Sometimes, a very tiny detail might cause a significant discrepancy, and it can be challenging to reveal this.
If we look at electromagnetic compatibility (EMC), we can find an example of a typical misconception. A standard initial request of a potential customer dealing with an EMC issue is: “Please put all the system including all the nonlinear circuits and mechanical parts into the 3D EM simulator and show us the agreement of emissions to our measurement”. This is a very inefficient approach since it would require a lot of time to transfer all the complexity of the device to the virtual model including, possibly, the effects of the environment where the device being tested was measured. Regardless, this approach won’t help to solve the EMC issue if the aim is just to replicate the measurement with the simulation. Instead, we recommend capturing only the most relevant portion for the principal study and finding the emission sources utilizing field visualization. As soon as we understand the how the emissions are generated, we can take action to suppress them. Typically that can be achieved just by modifying the PCB layout. Then, we may add a bit more complexity in the final step before applying changes to the physical sample to complete the verification loop.

The future of CST Lab

Our efforts with CST Lab are well received, and our customers actively cooperate since they see the benefits of combining measurement and simulation.
During the last three years, we have developed several novel workflows that speed up the design process and which enable our customers to create much more robust virtual models with an accuracy we haven’t seen before. Besides the development of further new approaches, the most critical task and challenge for the future will be the transfer of this knowledge to technical practice.   In fact, CST recently jointly presented a course from the well-respected European School of Antennas titled “Combination of Measurement and Simulation.” This is a wonderful example of companies and academia coming together to promote this approach to design.

Want to learn more? Check out these webinars in our archive and sign up with MyCST to be notified of upcoming training, workshops and other CST Lab related events.

Related webinars:


Dr. Vratislav Sokol
Senior Application Engineer




Vratislav Sokol received his M.Sc. and Ph.D. degrees in radioelectronics from the Czech Technical University in Prague in 2000 and 2004, respectively. He was a post-doctoral research associate with Cork Institute of Technology in Ireland where he dealt with an ultra-wideband transceiver. His activities are focused on microwave circuit design and modeling using electromagnetic field simulators and precise microwave measurement and calibration. He has been with CST since 2006 as an application engineer.