General Paraboloid Of Revolution Research Articles

RF Field Build-Up inside a Manned Space Vehicle Using Novel Ray-Tracing Algorithm

The radio-frequency (RF) field mapping and its analysis inside a space vehicle cabin, although of immense importance, represent a complex problem due to their inherent concavity. Further hybrid surface modeling required for such concave enclosures leads to ray proliferation, thereby making the problem computationally intractable. In this paper, space vehicle is modeled as a double-curvatured general paraboloid of revolution (GPOR) frustum, whose aft section is matched to an end-capped right circular cylinder. A 3D ray-tracing package is developed which involves a uniform ray-launching scheme, an intelligent scheme for ray bunching, and an adaptive reception algorithm for obtaining ray-path details inside the concave space vehicle. Due to nonavailability of image method for concave curvatured surfaces, the proposed ray-tracing method is validated with respect to the RF field build-up inside a closed lossy cuboid using image method. The RF field build-up within the space vehicle is determined using the details of ray paths and the material parameters. The results for RF field build-up inside a metal-backed dielectric space vehicle are compared with those of highly metallic one for parallel and perpendicular polarizations. The convergence of RF field within the vehicle is analyzed with respect to the propagation time and the number of bounces a ray undergoes before reaching the receiving point.

Investigation of the mutual coupling between apertures on doubly curved convex surfaces: theory and measurements

A hybrid method of high-frequency approximation (UTD) and method of moments is used to calculate the mutual coupling between circular apertures on a doubly curved surface. This requires that the geodesics on doubly curved surfaces be found. To represent the aperture fields, a single waveguide mode approximation is used. In order to verify the theoretical results, a general paraboloid of revolution with circular waveguide-fed apertures was built at Ericsson Microwave Systems AB, Molndal, Sweden. This has given a possibility to verify the theoretical model for a general doubly curved surface against measurements. To the authors' knowledge, no such verification is available in the literature. It was found that measured and theoretical results in terms of mutual coupling agree very well for copolar coupling. As expected, the mutual coupling results are very dependent on the polarization. In fact, the definition of polarization directions and the need for polarization control are important issues for doubly curved conformal array antennas.

Surface-ray tracing on hybrid surfaces of revolution for UTD mutual coupling analysis

An angle invariance property based on Hertz's principle of particle dynamics is employed to facilitate the surface-ray tracing on nondevelopable hybrid quadric surfaces of revolution (h-QUASOR's). This property, when used in conjunction with a geodesic constant method, yields analytical expressions for all the ray-parameters required in the UTD formulation. Differential geometrical considerations require that some of the ray-parameters (defined heuristically in the UTD for the canonical convex surfaces) be modified before the UTD can be applied to such hybrid surfaces. Mutual coupling results for finite-dimensional slots have been presented as an example on a satellite launch vehicle modeled by general paraboloid of revolution and right circular cylinder. >

A novel ray tracing on general paraboloids of revolution for UTD applications

Analytical expressions have been obtained for the ray-geometry parameters on the general paraboloid of revolution (GPOR) using a novel technique known as the geodesic constant method. These ray parameters are in a one-parameter form and can be readily employed in high-frequency EM antenna scattering problems. As an example, the uniform theory of diffraction (UTD) mutual admittance results are presented for two antennas located on the GPOR arbitrarily, in three dimensions. >

Ray analysis of mutual coupling between antennas on a general paraboloid of revolution (GPOR)

A methodology has been presented for the first time for computing geometric parameters of a GPOR, necessary for applying high-frequency techniques to antenna analysis. The analytical expressions for the geometric parameters derived here could be readily applied to mutual coupling problems.