Near field focusing for security applications: design and optimization of RLSA antennas

The possibility of generating a pseudo-Bessel beam with a propagation distance of several hundreds of wavelengths in microwave and millimeter frequency band by using a Radial Line Slot Array (RLSA) is discussed. The antenna design has been obtained by making use of a holographic approach to assure the required aperture field distribution and by employing an ad hoc optimization tool to control the antenna slot layout. The predicted and measured antenna behaviors show that high efficiency and polarization purity can be obtained by such a compact and flat antenna, achieving at the same time both manufacturing and set-up simplicity.