A17.1.1 Note on using propagation models

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ITU-R P.452: ITU-R P.452-16 ITU-R P.452-14 (superseded)	‎A17.7 A17.6 (superseded)	about 0.7 GHz to 50 GHz	up to a distance limit of 10 000 km	Prediction method for the evaluation of interference between stations on the surface of the Earth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ITU-R P.1546: ITU-R P.1546-6 ITU-R P.1546-5 (superseded) ITU-R P.1546-4 (superseded) ITU-R P.1546-1 (obsolete)	A17.11 A17.10 (superseded) A17.9 (superseded) A17.8 (obsolete)	30 MHz – 4 GHz	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	600 MHz - 2 GHz	>0 – 1 000 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
ITU-R Rec. P. 1411	‎A17.12	300 MHz – 3 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 – 1 800 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