SoftWright - Longley-Rice (aka ITM) Propagation Module
From TAP Software
The Longley Rice (aka Irregular Terrain Model) Propagation module is the most flexible and popular TAP propagation module. It is valid for a wide frequency range from approximately 30 MHz to 30 GHz. The Longley-Rice model is an implementation of many of the equations presented in the NTIA Tech Note 101. In addition to expected parameters such as frequency, effective radiated power (ERP), antenna pattern and antenna heights a number of other parameters unique to Longley-Rice are employed. These include such things as climate and soil conditions, ground conductivity and dielectric constant.
The TAP program includes default values and suggested typical values, but allows the user to modify these constants when in possession of more accurate information. The program automatically calculates path elevations, effective antenna heights, horizon distances and terrain irregularity. Field intensity values are calculated at specified radial, tile or individual locations using basic median field and adjustments based on the Longley-Rice model.