Periodic SIW Leaky-Wave Antenna With Large Circularly Polarized Beam Scanning Range

d In this letter, we propose and demonstrate a periodic leaky-wave antenna (P-LWA) by loading transverse slot pairs (TSPs) and longitudinal slots (LSs) along substrate integrated waveguide. The proposed P-LWA is able to yield a circularly polarized beam, which scans continuously from backward, through broadside, and to forward. Furthermore, it is shown that a large circularly polarized beam scanning range requires maximally coinciding radiation patterns of TSPs and LSs. Hence, within the design and optimization of the proposed P-LWA, the radiation pattern of the TSP should be adjusted to match the radiation pattern of the LS. A resulting large circularly polarized beam scanning range from -40 degrees to 25 degrees has been predicted by simulations and experimentally verified. This circularly polarized beam scanning range turns out to be larger than inmost of the previously reported works.