NON-INVASIVE MICROWAVE RADIOMETRIC SYSTEM FOR INTRACRANIAL APPLICATIONS: A STUDY USING THE CONFORMAL L-NOTCH MICROSTRIP PATCH ANTENNA

Temperature variations in tissues inside the body have been measured using microwave radiometry for more than three decades in a variety of passive body monitoring applications. In this paper we study a non-invasive prototype system for passive intracranial monitoring using microwave radiometry. It comprises one or two (two-element array) L-notch microstrip patch antennas in conjunction with a sensitive multiband receiver for detection. The particular design characteristics of the antenna are its conformality and a special L cut on its upper left edge, features that make it suitable for human biomedical applications and lead to its multiband operation in the frequency range of 2-3 GHz. The theoretical electromagnetic study indicates that the radiometric contact system in question operates well at two frequencies, with satisfying detection depths and adequate portability (small dimensions). In order to verify the findings of these simulations, experimental measurements with phantoms and various setups were carried out, resulting in the definition of the actual temperature detection level and the spatial resolution of the system. Theoretical and experimental results conclude that with the appropriate combination of conformal patch antennas and microwave receiver it is possible to monitor areas of interest inside human head models with a variety of temperature resolutions and detection depths.