ITU-R P.528-4 PDF

This Recommendation contains a method for predicting basic transmission loss in the frequency range 125 MHz to 15.5 GHz for aeronautical and satellite services. It provides a step-by-step method to compute the basic transmission loss. The only data needed for this method are the distance between antennas, the heights of the antennas above mean sea level, the frequency, and the time percentage.

This Recommendation, also, gives the calculations for the expected protection ratio or wanted-to-unwanted signal ratio exceeded at the receiver for at least 95% of the time, R (0.95). This calculation requires the following additional data for both the wanted and unwanted signals: the transmitted power, the gain of transmitting antenna, and the gain of receiving antenna.

The ITU Radiocommunication Assembly,

considering

a) that there is a need to give guidance to engineers in the planning of radio services in the VHF, UHF, and SHF bands;

b) that the propagation model given in Annex 2 is based on a considerable amount of experimental data (see Annex 1);

c) that the aeronautical service often provides a safety of life function and therefore requires a higher standard of availability than many other services;

d) that a time availability of 0.95 should be used to obtain more reliable service,

recommends

1 that the integral software in this Recommendation should be used to generate basic transmission loss values and curves for terminal heights, frequencies, and time percentages likely to be encountered in the aeronautical services;

2 that the following Notes should be regarded as part of this Recommendation.

NOTE 1 – It should be emphasized that the generated values are based on data obtained mainly for a continental temperate climate.

NOTE 2 – The method gives basic transmission loss, that is, the loss between ideal loss-free isotropic antennas. Where surface reflection multipath at the ground station or the facility has been mitigated using counterpoises or a directional vertical radiation pattern suitable antenna radiation patterns should be included within the analysis.