A novel leaky-wave antenna combining an image NRD guide and a strip circuit

This letter presents a novel leaky-wave antenna which combines an image NRD (nonradiative dielectric) guide and a printed strip circuit. The proposed structure allows for an easier, cheaper and more flexible tapering mechanism than all previous leaky-wave antennas in NRD technology. The working mechanism is explained, and two different tapering strip-circuit topologies are proposed. Cosine tapered illuminations are designed using a two-dimensional leaky-mode analysis technique. Simulations with high-frequency structure simulator (HFSS) three-dimensional analysis are presented for validation purposes. Also, the influence of the feeding transitions for each printed-circuit design is studied. Results show the feasibility of one of the proposed designs, leading to a tapered radiation pattern with sidelobes level below -20 dB.