Revision of the license rule of radio stations operated in test facilities such as anechoic chamber was made so that no license was required as a extremely low power radio station under the conditions as follows;

1) Test facilities comply with the Notification 173 of the Ministry of Internal Affairs and Communications 2006, which have attenuation of electromagnetic wave more than 40dB.

2) The level of electromagnetic wave from test facility that is attenuated by Test facilities shall be less than the level specified by the Regulations for Enforcement of Radio Act.

However, the measuring method to distinguish a extremely low power radio station in these cases had not been established, then, this technical report is settled to present an actual and effective measuring method to judge if it is a extremely low power radio station or not.

This report specifies two kinds of measuring method for electromagnetic wave.

One is the direct measuring method outside of the test facility. The other is the indirect method by calculation on the base of facility’s performance.