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34 DESIGN007 MAGAZINE I FEBRUARY 2020 to the dielectric losses; the higher the loss tan- gent, the more pronounced slope you see. The inductance curve slopes down because of the finite size and thickness of the DUT. At low frequencies, the current path is determined by resistive losses; as a result, the current spreads out utilizing a bigger part of the structure. At high frequencies, the current path is dictat- ed by the path inductance, and inductance is smaller in smaller loops, so if the current has the opportunity to rearrange itself as frequen- cy changes, it will flow in smaller loops as fre- quency goes up. Co-planar fixtures are very convenient and universal, but they come with some limitations. Similar to the solder-wick fixture, the co-pla- nar trace represents not only a convenient way to attach a DUT, but it also creates a sneaky path between the two VNA ports, which lim- its the lowest impedance we can measure this way. Second, being generic, chances are that these fixtures will not match the geometry of our final usage of the component in our de- sign. However, this only has an impact on the inductance; the capacitance and ESR still can be assessed with high confidence. DESIGN007 References 1. Keysight SMD component fixture 16034E. 2. I. Novak, "Solder-wick trick characterizes bypass caps," EDN, May 9, 2018. 3. Picotest DTBK01 decoupling test board kit. 4. I. Novak, "Make simple fixtures from SMA connec- tors," EDN, August 27, 2018. 5. SV1AFN RF experimenter's PCB panel of eight pieces. 6. I. Novak, "Why 2-port low-impedance measurements still matter," Signal Integrity Journal, January 16, 2020. 7. Picotest common-mode transformer J2102B. 8. Picotest PDN cable PDNCBL0P5M. 9. I. Novak, "Quiet Power: How to Read the ESR Curve," The PCB Design Magazine, November 2012. Istvan Novak is the principal signal and power integrity engineer at Sam- tec with over 30 years of experience in high-speed digital, RF, and ana- log circuit and system design. He is a Life Fellow of the IEEE, author of two books on power integrity, and an instructor of signal and power integrity courses. He also provides a website that focuses on SI and PI techniques. To read past columns or contact Novak, click here. The Bartolomeo research platform, developed by Air- bus for the International Space Station (ISS), has been de- livered to the Kennedy Space Center in Florida, USA. The move marks a further step toward something never before seen in space. With its planned launch in March, the Euro- pean-built Bartolomeo is set to become the first commer- cial research platform to be attached to the ISS. Bartolomeo is funded by Airbus and will be operated with the support of the European Space Agency (ESA). The platform can host up to 12 different payload slots, also providing them with a power supply and data transmis- sion back to Earth. With Bartolomeo, Airbus is offering fast and cost-effi- cient access to research in space, which can also be used by private data service providers. The platform's unique vantage point 400 kilometers above the Earth offers un- obstructed views of our planet. Not only does this provide opportunities for Earth observation, but also for carrying out measurements related to environmental and climate research—for example, the concentration of nitrogen ox- ide or CO 2 in the Earth's atmosphere. Bartolomeo will now be subject to further inspections at the Kennedy Space Center before being integrated into a Dragon space transporter. The launch is currently scheduled for March 2, 2020. (Source: Airbus) Bartolomeo Starts Its Journey to the International Space Station

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