Các bản vẽ kỹ thuật để chế tạo là sản phẩm cuối cùng của khâu thiết kế. Chúng phải thỏa mãn hai mục đích: bao gồm đầy đủ tất cả các thông tin cần thiết để chế tạo và cũng còn là một tiêu chí kiểm soát kỹ thuật đối với các mức độ sửa chữa. Trước cuối thế kỷ 20, rất nhiều bản vẽ kỹ thuật được thực hiện bằng tay với sự trợ giúp của bảng vẽ cơ khí. Sự ra đời của máy tính với giao diện người dùng đồ họa đã có thể giúp thực hiện. | Planar Antennas For Satellite Communications 381 Studio for the FDTD method. After a careful analysis comparing results with measurement of 4 common planar antennas their conclusion is as follows Classical patch antennas could be predicted by every simulation program with a deviation not beyond . The simulation based on MoM was inherently faster and are more attractive in price. On the other hand the FEM and FDTD are inherently able to analyze much more general structures but require the inversion of much larger but sparse matrices requiring higher memory resources. Although the calculation times were not that different at the time of experiment they presented a reference in which it seems that dedicated inversion techniques for MoM solvers are nowadays fully in development opening the possibility that better times can be obtained for differential equations solvers. Proper mesh generation and a correct feeding model are two crucial issues predetermining the successful simulation in the software packages reviewed. In general a very neat adaptive mesh refinement implemented in Ansoft s HFSS and as an option in CST s MWS allows better handling of a design with difficult electromagnetic coupling between its different parts. Such characteristics pertain to applications in mobile gadgets such as the GSM antennas. Having no mesh refinement option MoM-based programs require more careful consideration of the initial meshing. MoM solvers can provide an improvement in simulation results and time using so called edge-meshing features while avoiding excessive meshing on the bulk of the metal structure. However the study concludes that the meshing schemes in all solvers are adequate. Some designs such as the GSM and UWB antennas require finite substrate effects to be taken into account such as diffraction from substrate edges. MoM based solvers show better convergence when a dielectric substrate is infinite but the trend toward miniaturizing antennas diminishes the advantage
