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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 spring 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 an inclination of the antennas within the arc at 30°. 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.