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In this communication, a parabolic shaped complementary cloak is proposed which makes the object invisible by reducing its scattering under different incidence angles of electromagnetic wave. The proposed design is based on transforming a line segment into an enclosed space that is surrounded by the core region. The enclosed space is symmetrically divided into two regions, namely, cloaked region and complementary region. The shifted parabolic coordinate system introduced in the present work enhances the area of cloaked region and provides diagonally anisotropic but optimized homogeneous material properties in the core region. The cloaked region is mapped onto the complementary region using a simple one directional folding transformation, which yields homogeneous and isotropic material properties in the complementary region and also eases the creation of antiobject. Numerical results confirm the cloaking effect of the proposed approximate complementary cloak. The metamaterial unit cell designs are also presented for realizing the proposed material properties of core and complementary regions. [ABSTRACT FROM AUTHOR]

In this paper, the B-scan technique is applied to a reverberation chamber (RC) for the first time to characterize the time-domain behavior of the chamber. Based on B-scan measurement results, three things are studied in this paper. 1) The statistical behavior of the fields in the time domain is investigated, and it is found that the received power of the impulse response follows chi-square distribution with one degree of freedom. 2) The stirrer efficiency is quantified based on the equivalent total scattering cross section (TSCS) of stirrers, and this definition is not sensitive to the antenna position and load in the RC. It is shown that the stirrer efficiency defined in this paper provides, for the first time, a quantitative way to evaluate the stirrer design and the chamber performance. 3) A time-gating technique is proposed which provides an alternative method to eliminate the early time response and obtain the chamber transfer function of the RC accurately. This could be potentially used to increase the stirrer efficiency without changing the stirrers physically. It is demonstrated that the B-scan technique is a very useful approach for the study and evaluation of an RC. [ABSTRACT FROM PUBLISHER]

The cloaking efficiency of a finite-size cylindrical transmission-line cloak operating in the X-band is verified with bistatic free space measurements. The cloak is designed and optimized with numerical full-wave simulations. The reduction of the total scattering width of a metal object, enabled by the cloak, is clearly observed from the bistatic free space measurements. The numerical and experimental results are compared resulting in good agreement with each other. [ABSTRACT FROM PUBLISHER]

A recent approach to physical bounds on antennas of arbitrary shape is numerically illustrated. In particular, physical bounds for antennas circumscribed by the rectangular parallelepiped, finite cylinders, and planar rectangles are presented. The bounds are verified against numerical results or various small antennas with excellent agreement. [ABSTRACT FROM AUTHOR]