Thought Leader Thursday: The Role of Electromagnetic Simulations versus Measurements

Modern technologies are changing our lifestyles at a faster pace than ever. In today’s world, the importance of electronics, and wireless communications in particular, has became evident in everything we do. For instance, consider the systems coexisting in your car, navigation, crash and emergency, remote keyless entry and keyless go, tire pressure monitoring, Bluetooth, and more using advanced antenna systems. Other examples include mobile communication and navigation, internet of things (IoT), and even healthcare applications like magnetic resonance imaging (MRI).

Typical automotive keyless entry system scenario (from R. El-Makhour et al., VTC 2013).

Typical automotive keyless entry system scenario (from R. El-Makhour et al., VTC 2013).

Designing all these systems from an electromagnetic perspective requires two different focus areas:

  • Functional design—ensuring that the antenna systems meet the required specifications in terms of radiation patterns with respect to the environment, input impedance, specific near field distribution (MRI systems), bandwidth, and more.
  • Aspects of electromagnetic compatibility (EMC)— since these systems must operate alongside each other in a confined environment this is crucial. Unwanted radiation and coupling into other devices or cables can result in potential malfunctioning of systems, interference as well as human exposure to radiation.
EMC Immunity Test.

EMC Immunity Test.

In order to study the electromagnetic properties of a device or system, one must carefully consider functional design, EMC compliance, and interoperability issues. To a large extent, this is typically done by relying on prototype measurements, or the final product. While the role of electromagnetic simulations has increased over the past two decades, and gained more popularity and acceptance, its usage levels lag behind other engineering disciplines. Why? Are Maxwell’s equations that govern electromagnetic phenomena much more complicated? Are the software tools not mature enough? Are the problems too complex for simulations? Is it just simply too difficult to access the right simulation models?

Well, design engineers do not have to worry about Maxwell’s equations; this is taken care of by the software development teams behind electromagnetic simulation packages. For many years, general-purpose codes like FEKO have been available by offering multiple numerical methods nicely integrated in one user interface. The biggest challenge for electromagnetic simulations is that the world is quite complicated, and it’s often impossible to map this complexity one-to-one into a computer model. Thus, if certain electromagnetic effects must be analyzed using say a fully equipped car model, performing measurements on the final product is definitely the best approach.

Coupling of lightning currents into cables.

Coupling of lightning currents into cables.

However, the good news is that modeling this complexity is not always required. Even if assumptions regarding unknown material parameters must be made, extracting the relevant parts into a computer model for a specific analysis is sufficient in most cases. If in doubt, the accuracy of the computer model can be assessed by using measurements for one specific configuration, and then moving forward with the design and optimization by using numerical modeling without constantly building a new prototype. As a result, computer simulation can nicely complement measurements for a rapid design cycle!

One argument I have heard very often in the world of EMC is that most standards are written with measurements in mind, such as prescribing in detail of a specific measurement setup to assess compliance. Arguably, with the computer power and optimized numerical codes available these days, it is very well feasible to model not only the testing device, but to also include the measurement setup in the computer model! Or even going one step further by using numerical modeling to design and verify the measurement environment, shown below.

Modeling the quite zone (QZ) in an anechoic chamber.

Modeling the quite zone (QZ) in an anechoic chamber.

In summary, the power of rapid designs lies in the synergy of electromagnetic simulations and measurements. While numerical modeling of electromagnetic phenomena lags behind other engineering disciplines in acceptance and adaptation, it is maturing quickly due to ease of use, intuitive simulation codes, and powerful hardware solutions. For complex real-world problems, simulations should be seen as a complement to measurements, not as a replacement.

Ulrich Jakobus

Ulrich Jakobus

Vice President - EM Solutions at Altair
Ulrich joined Altair in 2014 with the acquisition of the South African based company EM Software & Systems where FEKO was developed originally, and is now the Vice President of EM Solutions at Altair. He has a strong focus in the development of the electromagnetic field solver package FEKO for the past 25 years. He graduated from the University of Stuttgart, Germany, in Radio Frequency Engineering with a concentration in Computational Electromagnetics.
Ulrich Jakobus
Ulrich Jakobus

About Ulrich Jakobus

Ulrich joined Altair in 2014 with the acquisition of the South African based company EM Software & Systems where FEKO was developed originally, and is now the Vice President of EM Solutions at Altair. He has a strong focus in the development of the electromagnetic field solver package FEKO for the past 25 years. He graduated from the University of Stuttgart, Germany, in Radio Frequency Engineering with a concentration in Computational Electromagnetics.