Experimental investigation of axial-null and axial-peak illumination schemes in microwave imaging

The performance of the recently proposed axial-null illumination scheme for microwave imaging has been experimentally investigated in comparison with the conventional axial-peak illumination. The axial-null scheme is implemented as an array of four simultaneously transmitting X-band waveguides physically oriented to produce zero field along the array axis. Two independent direct inversion algorithms - scattered-power mapping and microwave holography - are used for processing the respective data. It is shown that axial-null illumination provides reconstruction of better quality in comparison with the axial-peak illumination.