INSTRUMENT PORT SEAL FOR RF MEASUREMENT

摘要

An apparatus includes a blade clearance detection system. A probe is configured to communication detection frequencies from and gather reflected signals for the blade tip detection system. The probe has an end supported relative to the casing. A material provides a reference point. The blade tip clearance detection system is configured to generate a first detection frequency configured to pass through the material to detect the position of a target structure, generate a second detection frequency configured to reflect from and detect the reference point, and determine a position of a surface approximate to the target structure based upon the reference point.