Bessel beam generation with a RLSA antenna for non-contact detection of buried objects

To detect buried objects at a not well-defined distance of several meters from the radar system it is preferable to maintain the beam confined in a small spot of a few centimeters for a wide range. To this purpose a pseudo-Bessel beam having a propagation distance of several hundreds of wavelengths can be suitably used. This paper shows how this beam can be conveniently obtained in the microwave band by using a Radial Line Slot Array (RLSA). To assure the required aperture field distribution, the antenna design has been achieved by making use of a holographic approach and by employing an ad hoc optimization tool that provides directly the final antenna slot layout. Simulated and measured antenna characteristics show that high efficiency and polarization purity can be obtained by such a flat antenna, also achieving both manufacturing and setup simplicity.