This article aimed to optimize radar cross section (RCS) of the nose of flying objects using a new shaping method. In this method, parameters related to the scatterer shape can continuously change. Thus, precise optimization can be carried out. The nose of flying objects with desired size and sharpness was defined by mathematical formula with two parameters. The physical optics method was also applied to calculate RCS. Design curves were calculated by changing sharpness and size criteria of the nose of flying objects. Effects of changing frequency, angle of observation, and angle of incidence on RCS curves were also investigated.

We have previously shown that a new class of Negative Refractive Index (NRI) metamaterials can be constructed by periodically loading a host transmission line medium with inductors and capacitors in a dual (high-pass) configuration. A small planar NRI lens interfaced with a Positive Refractive Index (PRI) parallel-plate waveguide recently succeeded in demonstrating focusing of cylindrical waves. In this paper, we present theoretical and experimental data describing the focusing and dispersion characteristics of a significantly improved device that exhibits minimal edge effects, a larger NRI region permitting precise extraction of dispersion data, and a PRI region consisting of a microstrip grid, over which the fields may be observed. The experimentally obtained dispersion data exhibits excellent agreement with the theory predicted by periodic analysis, and depicts an extremely broadband region from 960MHz to 2.5GHz over which the refractive index remains negative. At the frequency at which the theory predicts a relative refractive index of -1, the measured field distribution shows a focal spot with a maximum beam width under one-half of a guide wavelength. These results are compared with field distributions obtained through mathematical simulations based on the plane-wave expansion technique, and exhibit a qualitative correspondence. The success of this experiment attests to the repeatability of the original experiment and affirms the viability of the transmission line approach to the design of NRI metamaterials.

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The metamaterial considered is a planar wire-grid network loaded with closely spaced, orthogonal capacitors and inductors, positioned over a ground plane and parallel to it. Excited by a single-frequency point source, this metamaterial exhibits conical high-field regions called "resonance cones" which extend outward from the source in directions predetermined by the load reactances, thus carrying RF power to specific points on the resistively terminated network edges. When two such metamaterials are interfaced, the cones traversing the interface can exhibit negative refraction as well as subwavelength focusing, phenomena supported by physical experiments and corresponding moment-method simulations. Poynting vector calculations based on the simulation data reveal power flow that follows the cones smoothly from the source and across the refraction interface. Electromagnetic field and Poynting vector calculations both exhibit potentially significant differences depending on whether they are done at the ground plane level or at the level of the anisotropic grid.

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