Measurement Technique for Evaluating Radio Frequency Absorption

This paper presents aspects regarding the measurement technique in order to implement the recommendations for evaluating the absorption of radio-frequency (RF) signals, according to IEEE Std. 1128-1998(R2012). To characterize the absorption properties of materials used in the field of signal absorption, the standard recommends several test methods, opting for the arch method. A type of RF absorber with pyramidal geometry was tested, the measurements being carried out in the frequency range 3 - 5 GHz, with horn antennas. A measurement without absorbents was first performed to determine the reference level. The reflection coefficients of the material were then measured for a positioning of the antennas at an angle of 30° inside the arc. The results obtained, which are tabulated, for different frequencies, indicate the level of absorption (loss) in the RF absorbing material. A procedure for measuring a basic property of RF absorbers is therefore proposed.