Atmospheric Attenuation Data
Attenuation data for each frequency is obtained using a combination of prediction models as recommended by ITU[1].
Free space path loss is based on [1][source code]
Rain attenuation is obtained from [2][source code]
Gaseous absorption is based on [3][source code]
Cloud attenuation is obtained from [4][source code]
For the sake of conciseness, only the results at 76 and 86 GHz are listed below. Attenuation at other frequencies can be calculated using the MATLAB code above.
Frequency: 76 GHz
Table 1. Simulated free space path loss, gaseous absorption, and rain attenuation at the selected Earth stations at 76 GHz
|
Earth Station |
Free Space Path Loss (dB) |
Gaseous Absorption (dB) |
Rain Attenuation(dB) |
| Georgia Tech | 223.9 | 3.7 | 99.4 |
| Virginia Tech | 224.7 | 4.1 | 78.4 |
| New Mexico Tech | 223.5 | 3.6 | 29.7 |
Table 2. Attenuation due to each of the main four types of clouds at 76 GHz
|
Cloud Type |
Attenuation (dB) |
| Cumulonimbus | 12.7 |
| Cumulus | 5.1 |
| Nimbostratus | 3.4 |
| Stratus | 1.0 |
The rain attenuation percentage in the three regions where our Earth stations are located were simulated using the models developed in MATLAB. Figure 1 contains the simulation results at 76 GHz.
Figure 1. Rain attenuation versus percentage of time
Frequency: 86 GHz
Table 3. Simulated free space path loss, gaseous absorption, and rain attenuation at the selected Earth stations at 86 GHz
|
Earth Station |
Free Space Path Loss (dB) |
Gaseous Absorption (dB) |
Rain Attenuation(dB) |
| Georgia Tech | 224.9 | 4.1 | 97 |
| Virginia Tech | 225.7 | 4.4 | 77.3 |
| New Mexico Tech | 224.5 | 3.9 | 30.1 |
Table 4. Attenuation due to each of the main four types of clouds at 86 GHz
|
Cloud Type |
Attenuation (dB) |
| Cumulonimbus | 14.3 |
| Cumulus | 5.7 |
| Nimbostratus | 3.8 |
| Stratus | 1.1 |
The rain attenuation percentage in the three regions where our Earth stations are located were simulated using the models developed in MATLAB. Figure 2 contains the simulation results at 86 GHz.
Figure 2. Rain Path Attenuation versus percentage of time
References:
[1] P.618 : Propagation data and prediction methods required for the design of Earth-space telecommunication systems. http://www.itu.int/rec/R-REC-P.618-10-200910-I/en.
[2] Dissanayake, A. , Clarksburg, MD, Allnutt, J. , Haidara, F., ”A prediction model that combines rain attenuation and other propagation impairments along Earth-satellite paths”, IEEE Transactions on Antennas and Propagation, Oct 1997.
[3] P.676 : Attenuation by atmospheric gases. http://www.itu.int/rec/R-REC-P.676/en.
[4] Stutzman, W. L., and W. K. Dishman (1982), A simple model for the estimation of rain-induced attenuation along earth-space paths at millimeter wavelengths, Radio Sci., 17(6), 1465–1476.