This invention relates to methods and apparatus for measuring physical properties using microwave cavity sensors. In operation, a number of microwave cavity sensors are interrogated by a remote wireless unit in order to determine the current resonant frequency for the sensor. The current values for various parameters measured by the sensors, such as temperature, stress/stain, or the like, are determined by comparing the current resonant frequency to a first resonant frequency of the sensor, and thus, detect any change in the value of the selected parameter. In particular, the present invention is directed toward extending the range over which such measurements may be performed, using these types of sensors.