SEAMCAT has the means to use built-in models but also the means of programming user-defined propagation models. The plugin concept was chosen to avoid the inherent format limitations of the earlier versions of SEAMCAT interface and make the plugin model to work as fast as any built-in model.
To aid in the selection process, Table 77 provides an indication of the application ranges and typical areas of suitability of the built-in propagation models in SEAMCAT
Table 77: Application ranges and typical areas for the various propagation models implemented in SEAMCAT
Model | Annex | Frequency range | Distance range | Typical application area |
Free space loss | A17.2 | LOS-limited | Fixed links and other systems/paths where direct-LoS could be assumed | |
Extended Hata | A17.3 | 30 MHz - 3 GHz | Up to 40 km | Mobile services and other services working in non-LoS/cluttered environment . Note that in theory, the model can go up to 100 km since the curvature of the earth is included, but in practice it is recommended to use it up to 40 km. |
Extended Hata-SRD | A17.4 | 30 MHz - 3 GHz | Up to 300 m | Short range links under direct-LOS assumption, important: antenna heights up to 3 m |
Spherical diffraction (ITU-R P.452) | A17.5 | Above 3 GHz | Up to and beyond radio horizon | Interference on terrestrial paths in predominantly open (e.g. rural) areas |
ITU-R P.452:
| A17.6 | about 0.7 GHz to 50 GHz | up to a distance limit of 10 000 km | Prediction method for the evaluation of interference between stations on the surface of the Earth at frequencies above about 0.1 GHz, accounting for both clear-air and hydrometeor scattering interference mechanisms. |
ITU-R P.1546:
ITU-R P.1546-1 (obsolete) |
A17.10 A17.9 (superseded) A17.7 (obsolete) | 30 MHz – 3 GHz |
<1 000 km | Broadcasting and other terrestrial services, typically considered in cases with high mounted transmitter antenna (e.g. above 50-60 m).
Note that ITU-R P.1546-5 is also valid for short horizontal distances smaller than 1 km.
Note that Rec. ITU-R P.1546-4 proposes a solution where values of distances less than 1 km may occur and where short-range propagation model is not practicable and a simple means is required to converge towards free-space field strengths for arbitrarily short distances (see section 14 of ITU-R Rec. P.1546-4). |
JTG5-6 | A17.9 | 30 MHz - 3 GHz | >0 – 1000 km | similar to ITU-R P.1546-4 but covering the distances below 1 km |
Longley Rice (ITM) | A17.10 | 20 MHz – 40 GHz | 1 – 2 000 km | Antenna height from 5 cm to 3 km and surface refraction from 250 to 400 N |
IEEE 802.11 Model C | A17.11 |
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ITU-R Rec. P. 1411 | A17.12 | 300 MHz – 100 GHz | < 3 km | § 4.3 of the recommendation; for propagation between terminals located from below roof-top height to near street level |
ITU-R Rec. P. 528 | A17.13 | 125 MHz – 15.5 GHz | > 0 – 1800 km | ground-air, ground-satellite, air-air, air-satellite, and satellite-satellite links |
Propagation plug-in | A17.1.4 | model specific | model specific | model specific |