ITU-R P618-12 Rain Model
An ITU rain model based on the most recent revision of ITU recommendation ITU-R P618. This model supersedes all previous releases of the rain model.
| Parameter | Description |
|---|---|
| Surface Temperature | The surface temperature used by the model. |
| Enable Cross Polarization Loss |
Models depolarization of a communications link due to rain. This option is available only for releases 10 and 12 of the P618 model. |
Tropospheric Scintillation
| Parameter | Description |
|---|---|
| Compute Deep Fade | Select to model strong destructive interference. |
| Surface Temperature | Enter the surface temperature value. |
| Tropo Fade Outage | Enter the Tropospheric Fade Outage as a percentage. STK will compute the loss in dB that will occur for the percentage time not exceeding the specified limit. |
| Percent Time Refractivity Gradient < -100 N | The percentage of time that the reflectivity gradient in the lowest 100 meters of the atmosphere is less than -100 N units/km. |
| Fade depths for the average year | Computes the fade depth exceeded for a percentage of time over an average year. For example, fade depth will exceed the computed value for the climate of an average year as a percentage of the time over the year. |
| Fade depths for the average annual worst month | Computes the fade depth exceeded for a percentage of time for the month with the worst climate over a year. Fade depth will exceed the computed value for a percentage of time over the worst month of the year. |
The Tropospheric Scintillation model is based on modeling RF energy in a beam with a certain beam width. Since Dipole antennas are omni-directional and do not provide a beam width, a standard dish antenna with 1.0 meter diameter and 70% efficiency is assumed for computing scintillation loss only. This does not impact link budget computations, which are still carried out for a dipole antenna selected as the system model.
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