In this paper the performance of basic elements, such as monopoles, apertures, and microstrip patches, when mounted on finite ground planes, ground-based vehicles and airborne platforms are modeled and simulated using high-frequency asymptotic methods [GTD/UTD] and full-wave methods [IE/MoM, FDTD and FEM]. While GTD/UTD shed more physical inside into the modeling, they generally are limited by the geometry of structures, constituent parameters, and small electrical size. On the other hand, full-wave simulators, such as IE/MoM, FDTD and FEM, (and commercial software such as WIPL-D, FEKO, HFSS and Xfdtd) are more versatile although usually they are limited by physical interpretation and large electrical size. The basic antenna radiation characteristic examined and simulated in this paper is the amplitude pattern formation and its distortion due to reflections, edge diffractions and rotor blade rotation. Typical amplitude patterns of radiators mounted on complex structures and airframes will be presented. In some cases simulated data is compared with measurements on scaled-models.