The paper deals with the measurement of individual components or circuits embedded in more complex radio frequency (RF) or microwave printed circuit boards (PCBs). Since no standard RF measurement enables the direct parallel connection of an analyzer to the boards being tested, individual components are often measured by destructively cutting manufactured boards and by attaching the RF connectors to the concerned parts. This article shows that this problem, thanks to suitable calibration standards that have been designed and manufactured, can be solved by vector measurements and a TRL calibration process. The measurements also work when the boards to be measured include frequency conversion. The applicability of the developed method has been verified by practical measurements and its accuracy influenced by variations of the parameters of the surrounding circuits has been investigated by an uncertainty analysis.