Optimization of planar periodic leaky-wave antennas by selective surface-wave suppression

Planar periodic `bull-eye´ leaky-wave antennas are investigated for two-sided frequency beam scanning and broadside radiation at microwave and millimeter-wave frequencies. In particular, the ground plane and the radial configuration of the structures are optimized to support leakage of the fundamental TM mode of the guiding structure in a regime without any other modes, either bound or radiating, while also taking into consideration the TM and TE fields generated by the practical slot source integrated into the bottom ground plane. These design approaches can improve beam scanning quality, reduce reflection losses, minimize cross-polarization levels, and increase antenna gain. In addition, full-wave simulations and antenna measurements are in agreement with the developed Method of Moments dispersion analysis where continuous wide-angle beam scanning is observed over a large radiating bandwidth.