MAKE EMC VISIBLE

Question:

How many frequency sectors and radio services share the frequency range from
9 kHz to 6 GHz in Germany?

CHECK YOUR ANSWER

Before things get technical, here are the procedures that must be followed:

Companies must comply with the Radio Equipment Directive when selling their radio products on the European Market. This is illustrated on the left side.

Anyone who wants to become a radio amateur must take exams at the BNetzA in Germany and must adhere to rules when setting up their station and communicating. See the picture on the right.

The following applies to both: Everyone is fully responsible for their actions and must follow the rules. Otherwise radio communication would not be possible!

Let's look at a practical example. The EMC measurement on the left looks extremely good, but unfortunately the limit is exceeded at 144 MHz. That's just a frequency for a HW-developer, but it interferes with the 2 m radio amateur band and is a violation of compliance. Measurements clearly showed the source of the interference, which is shown here in color. This is the internally PLL of the microcontroller. Changing capacitors will not be helpful. Only changing the software setting, the problem could be resolved - at the expense of a slower internal timing.

This is a nice example to realize how important it is to "MAKE EMC VISIBLE" for purposeful solving EMC-problems!

Let's take a look at the frequency behavior of a plug-in mikrocontroller board that is build into a software defined radio.

The questions would rise "How does it interact with the main PCB and which frequencies will be generated?"

Each circuitry such as the DC/DC-converter, the internal activity of the microcontroller and the data flow between the memory modules provides its frequency contribution.

By measuring the electromagnetic fields and displaying them in colored areas, a well-founded statement about the EMC behavior can be made.

Here the concept of "MAKE EMC VISIBLE" becomes clear!

Radio amateurs are familar with antennas. Some even build some of them themselves. Horizontal and vertical antenna patterns are also nothing new for them. But things get really interesting with 3D representations. These have to be simulated or measured. See the picture on the left.

Printed circuit boards (PCBs) also represent antennas, even if the developers or project managers do not want to admit it!

A well-thought-out PCB design is characterized not only by the inclusion of Signal-Integrity, but also by focusing of the Power-Integrity.

The electromagnetic energy generated on the PCB must be guided clearly and unavoidable radiation must be minimized!

Maxwell's equations describe the behavior of electric and magnetic fields, how they are generated by charges and currents and how they influence each other. Highly interesting, often demonized in electrical engineering lectures and completely neglected in the PCB- design process.

Without this, and without the implementation in practice, the understanding and rise of radio technology would not have been possible.

Not everything that looks like a classical antenna on the roof of the house is an antenna. A single wire can be used as a multiband-antenna. The length depends on the frequencies to be used. Structures can also radiate. The example shows a patch antenna, without which we couldn't use satellite navigation.

And PCBs? Just because they don't look like "classical antennas", does that mean they don't receive or radiate electromagnetical signals? Of course they do!

Every trace and every structure on the PCB must be considered as an antenna. Impedance matching for traces is essential. Furthermore, the power supply layers must also be examined and optimized for their frequency response.

Another thought: Excellent Wi-Fi antennas can be made extremely cheaply from traces of a PCB. Here, the antenna behavior of a trace is explicitly desired!

Anyone who has ever built a house knows what I am talking about. The same applies for PCBs! Like the floors of a house, the different layer must be selected wisely.

The goal of an EMC-compliant PCB-design is "first time right". Impossible? Not if you have experience!

Measuring and visualizing electromagnetic fields is very helpful in this regard. Interfering frequencies can be detected and improvements can be made.

If you need further information how to "MAKE EMC VISIBLE", please contact me!

Here is a list of different articles for the area of electronic development and amateur radio. These are written in German. At the moment I enjoy writing articles for the DARC magazine CQ DL. The list will be expanded in the coming years – perhaps with an article in English!

• "EMV sichtbar machen; Teil 1 bis 3", CQ DL, 02-04/2026
• "Funkgeschichte auf 62,5 MHz: Amateurfunk im Wandel der Zeit", CQ DL, 07/2021
• "Kabellose Freiheit im Maschinenbau: Autarker Funk-Sensor nutzt Enocean-Technologie", Perpetuum, 10/2007
• "Wireless Transmission System BWT", Perpetuum 02/2005
• "Design störfester Sensoren", EMC-Kompendium, 2003
• "Wahlspruch: Wer nicht wagt, der nicht gewinnt", VDI-Nachrichten, 2001
• "Ableitwiderstand und Ableitdämpfung von Kabeldurchführungen", EMC-Kompendium, 2000
• "Burst-Nahfeldtests", EMC-Kompendium, 1999
• "Entstörung von Mikroprozessorplatinen", EMC-Kompendium, 1998
• "Neue D/A-Wandler für genaue Signalsynthese", Systeme, 1997

I am happy when I pass on knowledge and the participants can put it into practice. I was able to implement this in many events, such as the EMC trade fair in Stuttgart, workshops in STEM (MINT) topics like electronics and robotics at VDI Tecstatt, and lectures in the amateur radio sector.

Practical examples and demonstrators provide participants with understandable insights into the world of EMC-compliant electronic design.

Contact me, if you are interested in a workshop.

Important: The placement is carried out in accordance with the Code of Business Conduct (CoBC).