A simplified FEM calculation for 3D-field distribution from transmitter and presentation on geographic digital map

The conventional 2D-finite element method (2D-FEM) has been widely used in calculating the field distributions of transmitter within simple geographic structures (perfectly flat, perpendicular objects of infinite length). In practice, the geographic model of any region always consists of mountains, rivers or buildings, which require a general 3D-FEM calculation. The paper presents a simplified process for the 3D-calculations by exploiting the cylindrical structure of region, if ever, or decomposing its height into layers of truncated-prism elements. The calculation processes are still unchanged but the above tactics enable an efficient gain in microprocessor using time, especially for the 2nd-order finite elements. Moreover, these field distributions can be presented onto a digital GIS-based map, which helps to estimate the "dead zone" of fields within a real geographic region in transmitter design. Some modelized results are presented to illustrate these calculations