Radiation power measuring method and radiation power measuring apparatus

Abstract

Provided is a technique capable of accurately calculating the radiation power of an object to be measured using a spheroidal coupler even when there is a non-negligible loss in a measurement system. A phase rotating unit including a variable phase shifter, a two-branch circuit, and a reflective element that is connected to one of the branched outputs of the two-branch circuit is inserted between a receiving antenna and a power measuring device. The maximum value and the minimum value of power measured by a power measuring device when the variable phase shifter changes a phase are calculated. An output reflection coefficient of a coupler is calculated from the ratio of the maximum value to the minimum value, and an input reflection coefficient of an object to be measured which is approximate to the output reflection coefficient is estimated. In addition, an input reflection coefficient of a reference antenna which is used instead of the object to be measured is estimated in the same way. The total radiated power of the object to be measured is calculated on the basis of the estimated input reflection coefficients and the reception power when the power measuring device directly measures the output of the receiving antenna.