A.N. Gribanov, E.V. Ilyin, A.E. Zaikin, A.P. Volkov

This article displays possibilities of radiating systems\' electromagnetic modeling using finite-difference time-domain method (FDTD) and finite elements method (FEM). Electromagnetic characteristics were calculated for plane PAAs, both infinite and finite, of 77 to 3535 radiators. Test models of metallic waveguide PAAs with square and rectangular cross-sections were studied (fig. 2, 3), as well as PAAs with microstrip patch radiators (fig. 4-7). Both rectangular and hexagonal grids were implemented. The results are compared to existing publications. Model of infinite-size PAA is convenient for element\'s partial radiation pattern calculation. This gives power radiation pattern which has gives no information about its vector nature. In FEM, scanning is made by setting periodical boundaries of Floquet cell. This cell may has a shape of rectangle or parallelogram (for PAA with hexagonal grid). So FEM-based software is appropriate for model\'s initial geometric and electromagnetic parameters selection. This is useful also for model parameter\'s optimization and testing FDTD-based software\'s accuracy. Finite PAA\'s model allows radiator\'s vector partial radiation pattern calculation, i.e. it gives more information comparing to power pattern. Assuming that infinite PAA\'s radiator\'s partial pattern is very similar to that of quite large but finite PAA\'s central radiator, the last gives necessary information for any-size \"large\" PAA\'s model forming. FDTD-based software and available 24-Gbyte RAM PCs allows studying PAA models ranging from 1010 to 4040 elements in ultra-wide frequency band. Vector partial radiation pattern is calculated following its definition as PAA\'s pattern with central radiator being excited while all the last radiators are matched-loaded. Analytics of PAA scan blindness is numerically tested in waveguide and microstrip patch PAA\'s. Good tolerance is seen. Effects of grating lobes arrival and surface waves excitation in dielectric substrate are primary focused on. Expressions (2)?(4) are given that allows partial radiation pattern falls prediction with acceptable accuracy. Two approaches of scan blindness elimination are studied. The one is the rational choice of radiator\'s and PAA grid\'s parameters. The second approach is applicable to microstrip patch PAA and is based on using high-impedance electromagnetic surface (fig. 9-12).