Comtest Engineering

Did you know that amplifiers for reverberation testing chambers can be scaleable? Picking the proper amplifier is a major factor in the total costs of a new chamber. That is one of the reasons we teamed up with Rohde & Schwarz, the global market leader in EMC and immunity test solutions, including solid-state RF Microwave amplifiers in various frequency bands/bandwidth combinations and power classes.   Their EMC Solution Specialist in Denmark, Martin Randrup Villadsen, explains the benefits of our cooperation for clients. “All information Comtest feeds us in the design phase helps us predict and calculate a suitable amplifier. They are very accurate in their designs, which makes Rohde & Schwarz more competitive in our price proposals.”   Dimitrios Barakos, Reverberation Specialist at Comtest Engineering, confirms: “When you buy a chamber for a specific test, you need to know the range. For reverberation, the definition of the electric field is important. Sometimes, a more expensive chamber than the competition offers could save much money on the amplifier price. These elements, room and amplifier, influence each other in performance and price.”   Martin: “Clients should also try to think scaleable for future use. I know it’s complicated sometimes, but thinking ahead might save you the burden of building a higher room or replacing your amplifier. Some companies offer confusing ‘upgrades’ where they replace the amplifier with a new one at a discount. We have developed amplifiers with flexible modules, which can be truly upgraded. Nobody likes extra costs, so it’s better to think long-term, and together with Comtest, we can help you with that.”   In the photo, an example of an excellent combination for radiated immunity is the R&S®BBA300 Broadband amplifier, which provides linear high power over ultra-wide frequency ranges, combined with the Comtest Z-fold stirrer for our LUF-200.   Do you want to know if your reverberation chamber is scaleable and futureproof? Contact one of our technical consultants, Hanneke Mertens - van Veen, Marc Le Roy, or Uliana Trucchi.

At our table during the 7th Annual IEEE Long Island MTTS/APS Symposium in Long Island (NY), we will demonstrate the new Javelin Tip closed-cell absorber family we developed with our sister company, Dutch Microwave Absorber Solutions (DMAS).   These absorbers are free from dust, glue, and chemicals and are a futureproof solution for dirty, old-fashioned absorbers. Many test chamber engineers suffer from particles leaking from old absorbers. These particles not only cause a dirty working environment with the occasional smudgy lab coat, but they also contain hazardous chemicals.   Come to our table on May 16 and ask our representative, Russell C. Pepe, RCDD, from Advanced Technical Marketing, for one of the 15 exclusive Comtest hand gels to keep your hands clean until we help you upgrade your chamber into a safe and clean workplace.   The Long Island RF/Microwave Symposium & Exhibits is the area's premier annual event, bringing together the Microwave, Millimeter Wave, and RF community. This event is free for attendees, but they must register (see link in comments) for admission to the exhibit floor, technical lectures, complimentary lunch, networking event, and complimentary dinner.   The IEEE is organising the event, which will take place on Thursday, May 16, 2024, from 10:00 AM to 8:00 PM. The venue is the Radisson Hotel, 110 Vanderbilt Motor Pkwy, Hauppauge, Long Island.

It is not easy to replace soldered finger-stocks in the doorframe of your test chamber. That's why we switched already in 1999 to screw clampings. Our colleague Gerco van Diemen explains why you will benefit from this. "Clampings hold the finger-stocks in place. Finger-stocks are the copper clamps that ensure that the door of a test chamber is completely sealed and no RF leakage occurs. They are a vulnerable part of a chamber's Faraday cage construction. Traditionally, these are soldered, but we have developed a way where using screws has the same protective effect."   Why would you want to replace the finger-stocks? Gerco: "Opening and closing the doors regularly makes them dirty, and dirt reduces the insulation performance. This is why we advise our customers to have the doors cleaned by us every two years. But sometimes, typically after >20 years of usage, the finger-stocks are worn out from heavy use and must be replaced before the shielding starts to suffer. Removing soldered finger stocks is very laborious, and we want to take our customers' chambers out of production for maintenance as short as possible."   Are you unsure if dirty or worn finger stocks are compromising the performance of your test chamber? If so, contact one of our technical consultants for advice. Hanneke Mertens - van Veen, Uliana Trucchi or Marc Le Roy will be happy to help.

Comtest Engineering and Rohde & Schwarz are collaborating to offer optimised reverb test system solutions for all relevant compliance standards such as IEC 61000-4-21, ISO 11451-5, ISO 11452-11, MIL-STD-461G, RTCA/DO-160G, EUROCAE/ED-14 and various automotive OEM standards.   Why? Real-world electromagnetic environments are changing, driven by highly integrated electronic products with multiple, widespread interference sources. Conventional two-dimensional illumination techniques cannot fully address such complex test scenarios. Therefore, demand for EMC tests in Reverberation Chambers (RVC) is growing.   Rohde & Schwarz’s Product Manager Jens Medler says, “RVC is also in discussion for CISPR 32 emission measurements above 1 GHz. Our fully compliant EMI test receivers, broadband amplifiers, R&S ELEKTRA automation software and other system components enable immunity and emission testing in RVC chambers.”   Bas de Groot, Owner of Comtest Engineering, explains, “A reverb room is equipped with an integrated mode stirrer system that turns stepwise during testing. The benefits of mode-stirred RVC chambers are high repeatability, testing heavy and large EUTs, and better representation of real-life environments.”   Comtest offers worry-free EMC test chamber solutions. Rohde & Schwarz offers industry-leading EMC test solutions for everything from debugging to full compliance.

In our booth at the AMTA - Antenna Measurement Techniques Association 2024 Regional Meeting in Dayton/Fairborn (Ohio), we will demonstrate the new Javelin Tip closed-cell absorber family we developed with our sister company, Dutch Microwave Absorber Solutions (DMAS). These absorbers are free from dust, glue, and chemicals and are a futureproof solution for dirty, old-fashioned absorbers. Many test chamber engineers suffer from particles leaking from old absorbers. These particles not only cause a dirty working environment with the occasional smudgy lab coat, but they also contain hazardous chemicals.    Come to our table on April 23 and ask our representatives, Tony Oliverio and Jerry Yocum, from Eqs Systems LLC, for one of the 50 exclusive Comtest hand gels to keep your hands clean until we help you upgrade your chamber into a safe and clean workplace.

What are the design criteria for CISPR25 towards absorber lining as per the latest standard version? CISPR 25 was initially published in 1995. The 5th edition, published in 2021, significantly expanded the category of receivers by including new technologies such as Wi-Fi, V2X, navigation, and more.   The standard has extended to upper frequencies from 2,5 to 5,925 GHz to keep up with technological advancements and improve overall quality. Another critical change in edition 5 is section 4.3.4, which describes that the performance of the absorption material shall be greater than or equal to 6dB from 70MHz – 5,925GHz. This is a significant change compared to edition 4, where the upper frequency was 2.5GHz.   Partial absorber lining Why is this important? Many automotive component test chambers are built with a so-called partial absorber lining, which means all walls and ceilings are covered with ferrite tiles. Still, roughly half of these surfaces are also covered with hybrid absorbers. The absorbers are typically installed around the test table in a ‘horse-shoe’ layout on the walls and ceiling. Moving the 6dB reflectivity requirement from 2.5 to 5,925 GHz means that surfaces covered with ferrite tiles only, the other half of the chamber, no longer comply with this section of CISPR25 ed.5.   Testing and upgrading If you already have a chamber, we can upgrade it by installing hybrid absorbers to cover the walls and ceiling completely. Additionally, if you need to have your chamber (also called ALSE) validated according to Annex I (long wire test method), we can perform that test for you. Comtest Engineering has the necessary equipment and skilled test engineers to conduct the test and demonstrate compliance.   One example of this proactive approach was with our client, Marjan Mak, from SIQ Ljubljana in Slovenia – the leading EMC laboratory in the region. “When we purchased a new chamber from Comtest last year, they informed me about the new CISPR25 requirements and offered an alternative design that met all the new requirements. As a top compliant EMC service provider, it is essential to be fully compliant ourselves. Meanwhile, the Comtest team upgraded our existing chamber to make it future-proof and 100% compliant.”   If you're a professional unsure about the adequacy of your materials, we're happy to offer a quick consultation and provide you with the necessary CISPR25 validation test via one of our technical consultants, Marc Le Roy, Hanneke Mertens - van Veen or Uliana Trucchi.

This is our new colleague, Elyan Burnett. He challenged us by asking if we could create a job for him where he could combine his theoretical knowledge with engineering in our workshop. “Elyan finished studying Mechanical Engineering at the mboRijnland last summer. In his third year, Elyan did an internship in our company, and we asked him to come back as soon as he got his diploma,” says his manager, André Oostdam. “Internships are a way to solve the recruitment challenges our sector faces.”   But how did a guy with a desk job end up in the workshop? Elyan: “The education had a huge emphasis on the theoretical part of the job, such as technical drawing, calculations, parts lists, and quotations; it’s great, but I love to use my hands as well. Besides, having ADHD doesn’t help sitting at a desk all day. When I discussed this, André said they were open to creating the first office/workshop job at Comtest for me. How great is that?”   Students interested in internships at Comtest Engineering can send their request to André Oostdam.

This is the first 4,0 by 4,2 metres sliding door our specialists welded on our new welding tables. Why is that such a big deal? We asked the man on the right, Gerco van Diemen. “Before we acquired these welding tables from Bernd Siegmund GmbH, we used assembly carts to lay the parts that had to be welded. First, we had to place the underframe and level it by hand. After that, we put the tubes for the doorframe. Finally, we had to narrow down the frames." "All in all, it took a lot of time. These new tables are already levelled, and with the many connection holes, the tightening is way easier than before. For a large door like the one in the photo, the tables are connected, allowing us to level up to 4 meters. I’m happy; it makes our work easier, 40% faster and more precise.”

Improper grounding of RF-shielded rooms happens more often than you would think. In this article, we interviewed our former colleague Jan Kappert about 'clean grounds', TEMPEST requirements, and Faraday cages. It’s better to be safe than sorry, so contact one of our technical consultants, Hanneke Mertens - van Veen, Uliana Trucchi or Marc Le Roy, for more information on proper grounding.    

Is it possible to build nine RF-shielded test rooms over three floors in a building full of columns? Read how our designer, Britt Lise Links, made a Tetris-like solution for our client, Volkswagen Infotainment GmbH. “There are many challenges in this project. First, I had to fit six new shield rooms on the second floor of this building, keeping doors away from the many columns and enough space to move between the different rooms. For this project, all test rooms must be wheelchair accessible, so the standard 50mm door threshold is not an option. Each shield room must have a window to keep a visual connection with the inside. These RF-shielded windows are covered with a thin maze of copper to maintain the Faraday cage, so visibility is reasonable.” Britt made this layout together with Volkswagen’s project manager, Ingmar Litter. He recalls the initial puzzle: “We made the first layout. Britt had some good ideas, such as rotating one of the chambers on the second floor to increase the space between the chambers and keeping the sliding doors from the pillars. I enjoyed our cooperation, and we are almost done with the project. Comtest built seven rooms in three weeks at the end of last year. The chamber on the third floor will be ready in a few weeks, so we at Volkswagen Infotainment are ready to use our well-needed extra testing capacity.” In the photo from left to right: Bas de Groot (Comtest), Ingmar Litter and Sebastian Simon Kowalski (Volkswagen Infotainment).