A system and method is disclosed for measuring the dimensions of physical objects. The systems and methods include a measuring instrument of significant length comprising an array of patch antennas arranged along the length of an elongate substrate such that the antenna array expands and contracts with the substrate. The system also includes a diagnostic computing device for measuring the array's electrical properties including resonance frequency and changes in said properties relative to reference electrical properties that correspond to a reference length of the array and substrate. Accordingly, based on the measured changes in electrical properties and the reference length, the diagnostic system can calculate the current length of the measuring instrument. Accordingly, the disclosed systems and methods can provide self-calibrating measuring systems and measuring systems capable of being deployed onto a structure for periodically calibrating the structure's dimensions as it expands or contracts during operation.