# tirempl

Path loss using Terrain Integrated Rough Earth Model (TIREM)

## Syntax

``pl = tirempl(r,z,f)``
``pl = tirempl(r,z,f,Name,Value)``
``[pl,output] = tirempl(___)``

## Description

example

````pl = tirempl(r,z,f)` returns the path loss in dB for a signal with frequency `f` when it is propagated over terrain. You can specify terrain using numeric vectors for distance `r` and elevation `z` along the great circle path between the transmitter and the receiver. The Terrain Integrated Rough Earth Model™ (TIREM™) model combines physics with empirical data to provide path loss estimates. The TIREM model is valid from 1 MHz to 1000 GHz. Note`tirempl` requires access to the external TIREM library. Use `tiremSetup` to set up access. ```
````pl = tirempl(r,z,f,Name,Value)` returns the path loss in dB with additional options specified by name-value pairs.```
````[pl,output] = tirempl(___)` returns the path loss, `pl`, and the output structure containing the information on the TIREM analysis.```

## Examples

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Calculate the path loss over flat terrain. Define the terrain profile for distances up to 10 km with step size of 100 m.

```freq = 28e9; r = 0:100:10000; z = zeros(1,numel(r)); Lterrain1 = tirempl(r,z,freq,... 'TransmitterAntennaHeight',5, ... 'ReceiverAntennaHeight',5)```
```Lterrain1 = 142.6089 ```

## Input Arguments

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Distances along the great circle path between the transmitter and the receiver, specified as a numeric vector with each value in meters. The number of distance values must be equal to the number of elevation values.

Data Types: `double`

Elevation values corresponding to the distance values along the great circle path between the transmitter and the receiver, specified as a numeric vector with each value in meters. The number of elevation values must be equal to the number of distance values.

Data Types: `double`

Frequency of the propagated signal, specified as a scalar or numeric vector with each element unit in Hz.

Data Types: `double`

### Name-Value Arguments

Specify optional pairs of arguments as `Name1=Value1,...,NameN=ValueN`, where `Name` is the argument name and `Value` is the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

Before R2021a, use commas to separate each name and value, and enclose `Name` in quotes.

Example: `'TransmitterAntennaHeight',50`

Transmitter antenna height above the ground, specified as a numeric scalar in the range of 0 to 30000. The height is measured from ground elevation to the center of the antenna.

Data Types: `double`

Receiver antenna height above the ground, specified as a numeric scalar in the range of 0 to 30000. The height is measured from ground elevation to the center of the antenna.

Data Types: `double`

Polarization of the transmitter and the receiver antennas, specified as `'horizontal'` or `'vertical'`.

Data Types: `string` | `char`

Conductivity of the ground, specified as a numeric scalar in the range of 0.00005 to 100 in Siemens per meter. This value is used to calculate the path loss due to ground reflection. The default value corresponds to the average ground conductivity.

Data Types: `double`

Relative permittivity of the ground, specified as a numeric scalar in the range of 1 to100. Relative permittivity is the ratio of absolute material permittivity to the permittivity of vacuum. This value is used to calculate the path loss due to ground reflection. The default value corresponds to the average ground permittivity.

Data Types: `double`

Atmospheric refractivity near the ground, specified as a numeric scalar in N-units in the range of 250 to 400. This value is used to calculate the path loss due to atmospheric refraction and tropospheric scatter. The default value corresponds to average atmospheric conditions.

Data Types: `double`

Absolute air humidity near the ground, specified as a numeric scalar in g/m^3 in the range of 50 to 110. This value is used 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`

## Output Arguments

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Path loss, returned as a scalar or 1-by-N vector with each element unit in decibels. N is the number of frequencies defined in the input `f`.

Path loss is calculated from free-space loss, terrain diffraction, ground reflection, refraction through the atmosphere, tropospheric scatter, and atmospheric absorption.

Information of TIREM analysis, returned as a structure. Each field of the structure represents an output from TIREM analysis.

## Version History

Introduced in R2019a