IEC IEEE 62704-3 pdf free download

IEC IEEE 62704-3 pdf free download.Determining the peak spatial-average specific absorption rate (SAR) in the human body from wireless communications devices, 30 MHz to 6 GHz – Part 3: Specific requirements for using the finite difference time domain (FDTD) method for SAR calculations of mobile phones.
It is most important that the components present in the DUT model are assigned the correct material dielectric parameters. After import of the CAD file into the FDTD simulation tool, the correct material shall be assigned to each object to be meshed. The components and dielectric properties should be verified by a CAD engineer familiar with the physical and mechanical construction of the mobile phone.
Prior to meshing, the cell size requirements shall be established. This can be done in several ways, including automatic mesh generation, by a CAD object or group of objects, or manually. In order to provide an accurate mesh that will require minimal computer memory and run times, it is common practice to use a graded mesh, also called non-uniform mesh [4]. A graded mesh allows the FDTD mesh cell sizes to vary with position in one dimension. This approach allows smaller cells to be used where needed in order to accurately describe small but important CAD objects. A typical application for smaller mesh cells is in the antenna region which usually consists of slots.
While the above basic approach is a good start, there are exceptions that shall be considered. For example, the CAD objects may not have continuous surfaces. This can happen when the surface of the object is formed by the combination of separate facets and these facets may not join precisely at their intersections, leaving unintended gaps. This problem can be mitigated by ‘healing” the object manually to close the gaps (the healing feature is usually available in most commercially available FDTD simulation tools to fix connection problems among CAD objects to be fixed). However, for CAD objects with large gaps it may be impossible to develop an accurate FDTD mesh without manual intervention.
It is recommended that the larger metallic components or parts should be made into separate objects for which specific grid settings can be applied. In particular, the antenna model shall be a separate object so that this structure can be meshed as accurately as possible. The metallic parts of the model shall be aligned and connected so that artificial floating of electrically connected objects does not occur. Usually the printed circuit board (PCB) is not well represented in the CAD model. It is typically modelled as a few thin metallic layers interleaved with dielectric material [5]. However, it is acceptable to model the PCB as one thick solid metallic object. It is important to note that if the PCB is not correctly modelled, it will be seen as an invalid CAD model according to 7.4.
In order to optimize the computational resources, the components in the DUT model, for instance components located inside shielded cans, that are not expected to have noticeable impact to SAR distributions may be removed [6]. Consequently, such metallic components shall be given meshing priority over a component of lesser impact on SAR distribution. Components with the same material dielectric property that are in physical contact shall be united to form one solid. As a minimum requirement, essential parts such as antenna, chassis, PCB, display or screen, battery, other relatively large metallic components and the dielectric material supporting the antenna shall be modelled accurately. The meshing order of the objects or groups of objects shall be specified so that objects that touch, or perhaps even overlap, are correctly represented in the FDTD model.
Once the meshing has been completed, the resulting FDTD model of the handset shall be viewed and verified for accuracy. Critical areas such as the antenna region and other conductive components shall be carefully examined since the most important objects of the DUT model are the metallic components because they have the biggest impact on the SAR distribution.IEC IEEE 62704-3  pdf download.