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Implementation of the multifilament current method (MFCM) to analyze the scattering from homogeneous anisotropic cylinders is introduced. The ${z}$ -directed electric and magnetic line sources are used to associate with TM and TE polarizations, respectively. The radiation fields of a line source in unbounded space occupied with an anisotropic material are derived in detail. With the help of the derived fields, the application of the MFCM is expanded to anisotropic materials. The scattering field is then obtained in terms of these line sources. Monostatic and bistatic scattering widths of cylinders with and without sharp edge are investigated under different incident wave polarizations and material characteristics. Apart from homogeneous anisotropic cylinders, the scattering from an anisotropic shell-coated PEC cylinder is also straightforwardly analyzed without additional considerations in the formulation. The oscillation phenomenon of filament currents in representing the scattered fields and the ill-conditioned issue of the constructed matrix are also discussed in detail. Numerical results obtained with this proposed scheme are also in good agreement with published ones, whereas the proposed technique has its merits on simplicity and conciseness in comparison to the existing numerical methods. [ABSTRACT FROM AUTHOR]

We propose a wideband theory for adjoint variable sensitivity analysis of problems with non-dispersive anisotropic materials. The method is developed based on the transmission line modeling (TLM) technique. The anisotropic material property can be the full tensors of permittivity, permeability, electrical conductivity, magnetic resistivity, magnetoelectric coupling, or electromagnetic coupling. The tensors are assumed constant and may contain non-diagonal elements. Our algorithm estimates the gradient of the desired response with respect to all the designable parameters using at most one extra simulation, regardless of the number of parameters. The theory has been implemented in an algorithm for 2-D and 3-D structures. Our estimated sensitivities match well the computationally expensive central finite difference approximations. [ABSTRACT FROM PUBLISHER]

The purpose of this communication is to present the design of an artificially anisotropic antenna substrate (AAAS) for the generation of circular polarization (CP) for a linearly polarized antenna. The AAAS can be manufactured by assembling thin sheets with certain relative permittivities for the host or environment \varepsilon e and inclusion \varepsilon i materials as a stack. Using two different stacking materials enables the generation of different effective permittivities $\varepsilon _{{{x{'}}}}$ and $\varepsilon _{{{y{'}}}}$ for the wave components propagating in-between an antenna and a ground. The idea is to modify the antenna polarization by exploiting reflections from a ground in a way that CP operation is obtained. By properly designing the AAAS, the radiator shape can be maintained simple. The operation of AAAS is demonstrated for substrates made of homogeneous anisotropic and thin sheets. It is shown that by using sufficient high inclusion permittivity (e.g., \varepsilon _{i} = 15 ), the AAAS is observed to even show axial ratio <2 dB with over 25 dBi higher right-hand CP gain than left-hand CP in the main beam of the antenna. A prototype with available low-lossy materials is manufactured and successful correlation with theory and simulation results is observed. [ABSTRACT FROM PUBLISHER]

We present the potential use of reinforced continuous carbon fiber composite (RCCFC) material to build reconfigurable transmitter/receiver communication systems. The frequency agile characteristic is obtained by the rotation of the antennas on the ground plane which is made of anisotropic RCCFC material. The current distribution on the RCCFC composite ground plane can be controlled by exciting the desirable modes and eliminating the unwanted ones. Probe-fed rectangular microstrip-patch antennas are fabricated and the reconfigurable characteristics are investigated both numerically and experimentally. [ABSTRACT FROM PUBLISHER]