Impedance analysers ought to be simpler

November 16, 2016 // By Julien Happich
After a long career as an electronic designer at Philips, spending over 25 years designing analogue circuits, Wil Dijkman took his retirement as an opportunity to design yet new products, this time under his own name. On the electronica Fast Forward start-up platform, Dijkman was presenting a novel impedance analyser he started developing in 2012.

"Today's impedance analysers are very expensive, in the tens of thousands of euros, and often built as large complicated instruments", Dijkman pitches, "If you take a look at the HP4194A designed in the 70s and still in use today, it is massive with 60 buttons on its interface, you would almost get frightened by it and don't know where to start."   

The impedance analyser characterizing a coil.

In comparison, Dijkman's hand-made units retail for just under 2300 euros and are simpler to use, with 11 soft buttons for easy access to measurement, monitoring parameters such as |Z|, Φ, L, C, Rs, Rp, D, Q and X in real time and in different readout combinations. This allows engineers to identify subtle differences between different brands and types of capacitors and inductors, or to map the parasitics of high frequency transformers, or simply to determine with precision the characteristic impedance of coaxial cables or unshielded twisted pair (UTP) lines.

While offering performance comparable to much more expensive instruments from the competition, the low-cost USB impedance analyser is portable too, measuring only Size 250x250x50mm. This makes it suitable for small labs or education where it can characterize analogue filters, coils and transformers, Elcaps (value and ESR).

For now, the retired engineer is accepting orders in small numbers. Dijkman is open to licensing his know-how to larger T&M vendors, although he says his instrument operates on the principles described in the "Impedance Measurement Handbook" published by Hewlett-Packard, Agilent and Keysight, freely available online, and he struggles to understand why T&M vendors do not offer cheaper and more user-friendly impedance analysers.