Resonantly loaded apertures for high-resolution near field surface imaging

A novel type of microwave probes based on the loaded aperture geometry has been proposed and experimentally evaluated for dielectrics characterization and high-resolution near field imaging. Experimental results demonstrate the possibility of very accurate microwave spectroscopic characterization of thin lossy dielectric samples and biological materials containing water. High resolution images of the subwavelength lossy dielectric strips and wet and dry leaves have been obtained with amplitude contrast around 10-20dB and spatial resolution better than one tenth of a wavelength in the near field zone. A microwave imaging scenario for the early-stage skin cancer identification based on the artificial dielectric model has also been explored. This model study shows that the typical resolution of an artificial malignant tumour with a characteristic size of one tenth of a wavelength can be discriminated with at least 6dB amplitude and 50 degrees phase contrast from the artificial healthy skin and with more than 3dB contrast from a benign lesion of the same size. It has also been demonstrated that the proposed device can efficiently deliver microwave energy to very small, subwavelength, focal areas which is highly sought in the microwave hyperthermia applications.