At 224Gbps data rates, test fixtures and PCB materials must improve. Using a target of 67GHz for high-quality s-parameter measurements, various PCB materials and test fixtures are evaluated. The evaluations include low-loss dielectrics, smooth PCB copper, and 1.85mm co-ax fixtures. These are combined to make PCB trace measurements, plus co-ax and twinax cable measurements. De-embedding techniques are used to extract loss per length values for simple trace and twinax structures. Results are analyzed for measurement quality and suitability for 224Gbps component verification.