The so-called Okumura-Hata curve is an approximation of radio wave propagation characteristics based on aggregated data obtained in actual tests of propagation characteristics between a base station and mobile stations in various areas, such as open land, suburbs, a medium city, and a large city.  The electric field intensity for each area is calculated by applying a correction value to the standard field intensity, which is that of an urban area in quasi-smooth terrain.

Although the testing was carried out some time ago, the results are still being used as important basic data for radio wave propagation characteristics.  However, since the method of classifying the areas such as urban and suburban is not always clear, differences in the calculated values may arise according to which type of area the local system is assumed to be located.  In addition, the data for propagation characteristics is for when the base station antenna is higher than the surrounding buildings, and there are slight differences from the environment of use of specific low power radio equipment.  Therefore prudence is required in judging the validity of the calculation result.
 

< Formula >

Approximation conditions

Frequency: 150MHz - 1500MHz

Communication range: 1Km - 20Km

Base station antenna height: 30m - 200m

Mobile station antenna height: 1m - 10m

Approximation

Here A and B are the same for each area.  a(hm) and C have different values for each area.
Furthermore, in large cities, the a(hm) value differs according to whether the working frequency is above or below 400 MHz.

Parameters

< Common to all areas >




<Open land >




< Suburbs >

< Medium city >



<Large city >

*Please use the results of the calculation as a reference value.