TIREM

TIREM propagation model

Description

Model the behavior of electromagnetic radiation from a point of transmission as it travels over irregular terrain, including buildings, by using the Terrain Integrated Rough Earth Model™ (TIREM™) model. Represent the TIREM model by using a TIREM object.

The TIREM model:

• Is valid from 1 MHz to 1000 GHz.

• Calculates path loss from free-space loss, terrain and obstacle diffraction, ground reflection, atmospheric refraction, and tropospheric scatter.

• Provides path loss estimates by combining physics with empirical data statistics.

To predict path loss in scenes that feature buildings, such as urban environments, consider using a ray tracing propagation model. For more information about ray tracing models, see RayTracing.

TIREM objects require access to an external TIREM library. For more information, see Access TIREM Software.

Creation

Create a TIREM object by using the propagationModel function.

Properties

AntennaPolarization — Polarization of transmitter and receiver antennas

"horizontal" (default) | "vertical"

Polarization of transmitter and receiver antennas, specified as "horizontal" or "vertical". The object assumes both antennas have the same polarization. The model uses this value to calculate path loss due to ground reflection.

Data Types: char | string

GroundConductivity — Conductivity of ground, in S/m

0.005 (default) | numeric scalar in the range [0.0005, 100]

Conductivity of the ground, in S/m, specified as a numeric scalar in the range [0.0005, 100]. The model uses this value to calculate path loss due to ground reflection. The default value corresponds to average ground.

Data Types: double

GroundPermittivity — Relative permittivity of ground

15 (default) | numeric scalar in the range [1, 100]

Relative permittivity of the ground, specified as a numeric scalar in the range [1, 100]. Relative permittivity is expressed as a ratio of absolute material permittivity to the permittivity of vacuum. The model uses this value to calculate the path loss due to ground reflection. The default value corresponds to average ground.

Data Types: double

AtmosphericRefractivity — Atmospheric refractivity near ground, in N-units

301 (default) | numeric scalar in the range [250, 400]

Atmospheric refractivity near the ground, in N-units, specified as a numeric scalar in the range [250, 400]. The model uses this value to calculate the path loss due to refraction through the atmosphere and tropospheric scatter. The default value corresponds to average atmospheric conditions.

Data Types: double

Humidity — Absolute air humidity near ground, in g/m³

9 (default) | numeric scalar in the range [0, 110]

Absolute air humidity near the ground, g/m³, specified as a numeric scalar in the range [0, 110]. You can use this value to calculate path loss due to atmospheric absorption. The default value corresponds to the absolute humidity of air at 15 degrees Celsius and 70 percent relative humidity.

Data Types: double

Object Functions

pathloss	Path loss of radio wave propagation
add	Add propagation models

Examples

Model Coverage Using TIREM™

Display the coverage area for a transmitter using the TIREM model.

pm = propagationModel("tirem");
tx = txsite("Name","Apple Hill","Latitude",42.3001,"Longitude",-71.3604);
coverage(tx,pm)

More About

N-Units

The refractive index of air, n, is related to the dielectric constants of the gas constituents of an air mixture. The numerical value of n is only slightly larger than 1. To make the calculation more convenient, you can use N units, which are given by the formula: $$N=(n-1)\times {10}^6$$.

References

[1] Seybold, John S. Introduction to RF Propagation. Hoboken, N.J: Wiley, 2005.

Version History

Introduced in R2017b