Annular reconfigurable metasurface for omnidirectional dual-pol leaky-wave antennas

A printed annular reconfigurable metasurface (ARM) comprised of concentric ring slots etched in a metal screen loaded by stubs and varactor diodes is proposed to realize two-dimensional leaky-wave antennas (LWAs) operating on a pair of azimuthally independent TM and TE cylindrical leaky modes. The metasurface, used as a superstrate for a grounded dielectric slab, is designed to achieve wavenumber equalization of the two modes. These are excited independently by means of a vertical coaxial probe and a horizontal microstrip loop, thus allowing for radiation of an omnidirectional conical beam with reconfigurable beam angle and polarization. Theoretical and numerical investigations are presented, including an ad-hoc moment-method approach for the calculation of the antenna far-field patterns.