A practical method of measuring the scattering characteristics of the pyramidal absorber

The direct spatial standing-wave measurement method for the oblique incident case is investigated and extended to the method for measuring the scattering characteristics of the absorber. This method is used to measure the reflection coefficient from an absorber with an oblique incident wave. Here, the standing-wave ratio (or the scattering coefficient) and the scattering angle of the wave with the maximum intensity of all the waves are measured at the front surface of the sample. It is found that the measurement error of the standing-wave ratio around 1.1 (scattering coefficient, 0.04762) is less than + or - 20 percent in terms of the scattering coefficient for the incident angles ranging from 0 deg to 80 deg. The error in the scattering angle does not exceed 6 deg for the 0 deg scattered wave and is less than + or - 3 deg for all other scattering angles. It is pointed out that for a pyramidal absorber, measurements of the scattering characteristics can be made quickly over a wide range of frequencies and incident angles.