Status on Meta-Horn Development - Theory and Experiments

Hybrid-mode (HM) horn antennas with internal metamaterial wall liners, here denoted meta-horns and meta-liners, respectively, were first proposed in [1]. A soft meta-horn comprises a low index meta-liner with a given permittivity and thickness (see Figure 1b) that supports a balanced hybrid mode at the design frequency. These soft horns offer considerably larger bandwidth than the widely used corrugated horn due to evanescent propagation of the EM fields normal to the meta-liner. A hard meta-horn has a dielectric liner on top of a low index meta-liner as shown in Figure 2b. These horns also offer considerably larger bandwidth and comparable aperture efficiency when compared with other hard horns, which also is due to evanescent EM propagation normal to the meta-liner. Modeling and analysis of these meta-horns based on a cylindrical model as well as full-wave MoM analysis (WIPL-D) were reported in [1-4]. When compared with dielcore horns (Figures 1a and 2a) [4] both the soft and hard meta-horns exhibit comparable bandwidth performance without the disadvantages of insertion loss in the dielectric core, dielectric-air mismatch and additional weight. Full-wave analysis of both horns have shown that the desired frequency dispersion matches the Drude model, indicating that these low index meta-liners can be implemented with large bandwidth.