Height above average terrain

The Effective Antenna Height (short: Effective height, in English: Effective Antenna Height) is the height of the antenna center above mean ground level between 3 km and 15 km in the data required for calculation of wave propagation azimuthal direction.

The HAAT (English, Abbreviation for: height above average terrain ) is the height of the antenna center above mean ground level between 3 km and 16 km in the azimuthal also needed to calculate the wave propagation direction.

Effective height

The effective height of wave propagation models such as ITU -R P.370 and ITU -R P.1546 needed to calculate the field strength in the VHF range. It is an important parameter in the coordination of radio frequencies to transmitter sites and is defined in various international agreements for frequency coordination. Among other transmitter parameters, the effective height of the transmitting antenna is usually given by 36 values ​​for azimuths from 0 ° to 350 ° in 10 ° increments. Sometimes the maximum effective height of the transmit antenna is referred to. This is the maximum of the above 36 values.

HAAT

The HAAT is a similar parameter which e.g. is used in North America for frequency coordination of radio stations. It differs mainly by the averaging of the terrain data to 16 km instead of only up to 15 km at the effective height.

In North America (especially in the U.S.) the HAAT a transmitter has an impact eg on its performance class. For this, the HAAT values ​​for azimuths from 0 ° to 315 ° in 45 ° increments are determined and formed the arithmetic mean. Special attention should be doing azimuths that cross large bodies of water or cross the border of the USA.