QSW will evaluate the toolset developed within the FITS project by using it to parallelise an Alenia Spazio application: `RIVIA'.
RIVIA is a Fortran 77 code which analyses the radiation patterns of complex antenna systems by means of techniques based on physical optics (PO). Every system can be decomposed into a number of radiant sources and radiant surfaces. The PO technique is based on the calculus of the equivalent currents induced in the system under observation and the subsequent numerical integration to evaluate the irradiated electromagnetic field.
Metal, dielectric and dicroic surfaces can be described analytically or numerically. The multiple interactions among reflectors, blocking effects, single effects of illumination and radiation can be accurately evaluated. Each reflector can be evaluated more than once, allowing the estimate of second-order effects such as `back scattering'. The analysis of dicroic surfaces is done taking into account their actual width.
Numerical outputs are available at each step of the analysis, concerning each reflector under different illumination situations. It is possible to perform a phase or amplitude correction of the irradiated field when such a field is calculated on a sphere having a limited radius.
The RIVIA code spends a large proportion of its CPU time numerically integrating complex functions on predefined surfaces. Modern antennas have various characteristics that increase the computation time: high frequencies, surface dimensions that are large compared with the wavelength, and many surfaces within a single system.
Due to the fact that the integral is a linear operator, a well-suited parallelisation of the code should greatly reduce its computation time by, e.g., computing integrals in parallel.