No abstract

No abstract

No abstract

No abstract

Abstract-A full-wave analysis for determining the resonant frequency, quality factor and far-zone radiation patterns of a circular disk and annular ring microstrip patches, printed on a uniaxial anisotropic substrate is presented. Green's functions of the structure are determined in Hankel transform domain (HTD) using Hertz potential vectors. Galerkin's method, together with parsval's relation in Hankel transform domain is then applied to compute the resonant frequency and quality factor. The far-zone radiation patterns are expressed in terms of Hankel transforms of the tangential fields on the substrate. Wave equation is solved in cylindrical coordinates for the structure to estimate the basis function. The numerical results show that there are substantial deviations in calculated resonant frequency and quality factor when substrate dielectric anisotropy is considered. Furthermore, significant variations are seen in the radiation patterns of the structures due to substrate anisotropy. The variations of resonant frequency, quality factor and radiation patterns of the structure, with respect to anisotropy ratio of the substrate, for several values of substrate thickness and patch radius are presented.

A semicircle arc projection is introduced to miniaturize the patch in circular patch microstrip antennas. The idea has been inspired from the effectiveness of a cuboid ridge in size reduction of a rectangular patch microstrip antenna. A prototype of the proposed antenna together with a prototype of a conventional circular patch antenna has been fabricated and measured. The two antennas are compared, and the results are presented and discussed. A parametric study is also carried out on the characteristics of the arc projection.

An effective approach to reduce the patch size in rectangular patch microstrip antennas is presented. The proposed approach is based on inductively loading the patch using a cuboid ridge. A theoretical background of the approach using the transmission line model has been provided. A prototype of the proposed antenna is fabricated and measured. The results, advantages and limitations of the proposed approach are presented and discussed.

A Jaumann absorber with its metal backing replaced with a combined low-pass and polarizer FSS is investigated with respect to its absorption and its polarization-dependent low-frequency transparency properties. This structure is applied to an idealized curved wing-front end, and its monostatic radar cross-section is determined. The FSS-Jaumann structure preserves an absorption similar to the planar Jaumann absorber in the higher frequency interval and enables a partial transparency in the TEzpolarization at 1 GHz. In addition, once the structure is applied to the wing-front end, a significant reduction in two-dimensional radar cross-section for both the TMzand TEzpolarization over 2–16 GHz is observed. A sensitivity analysis shows that the resistivity of the inner resistive layer has a large impact on the 1 GHz transmission.