Ultra-wideband antenna array based on orbital angular momentum

In this work, an antenna array able to generate orbital angular momentum (OAM) electromagnetic waves with ultra-wideband (UWB) characteristics is proposed. In particular the proposed array antenna is based on cavity back UWB antennas. In particular each array element is backed with a surface impedance waveguide SIW to improve the performances and reduce the single element dimensions. The array elements are a circularly arranged and the correct phase shift, mandatory to obtain a suitable OAM wave, have been obtained with reconfigurable reflection type phase shifters based on two quadrature hybrids and commercial pin diodes. The phase shifters are driven by mean of a suitable micro-controller. A proof of concept prototype has been designed fabricated and experimentally assessed. The obtained results were quite promising.