Low-cost 0603 SMD Impedance Measurement Fixture

For microwave designs and when designing for electromagnetic compatibility (EMC), we need competent models of passive surface mount devices (SMDs), that is: resistors, capacitors and inductors. Such models are not always available or trustworthy, so we sometimes need to measure the impedance of these components ourselves. Appropriate measurement equipment exists, but often exceeds the available budget. In this paper, we design and build a low-cost test fixture that allows to measure the impedance of a 0603 SMD with a vector network analyser (VNA) or impedance analyser. Different fixture compensation methods are compared; a Short-Open-Load (SOL) calibration seems to be reliable up to about 12 GHz. The impedance precision depends on the used analyser.