| 摘要 |
<p>The invention relates to a method for determining the reflection coefficient of electromagnetic materials, screens or absorbents, with a view to electromagnetically characterizing new materials, determining the screening efficiency or reflection and absorption coefficients of electromagnetic materials, screens or absorbents. According to the invention, the method consists in that the electromagnetic reflection of materials is determined based on the index (m) of the modulation generated by some perfect electric conductor elements (1.2), rotating about their own symmetry axes, on the variable fixed incident field emitted by a transmitting antenna (2.2), where the elements (1.2) form together a variable screen (2.4) placed in front of a sample (2.5) to be tested which is periodically obturated and exposed thereby, the said index (m) being determined from the reflection - depending on the characteristics of the tested sample (2.5) - received by a receiving antenna (2.7), or by a compensating method, when the incident electromagnetic field emitted by the transmitting antenna (2.2), reflected by the screen system (2.4) and the sample (2.5) and received by the receiving antenna (2.7), becomes, by reflection, a constant amplitude field by controlling the emission modulation index (m), synchronized with the rotation of the variable screen (2.4), this way the field reflected by the test zone being identified and the contribution of the other electromagnetic fields being eliminated to allow determinations in an electromagnetically non-controlled medium or in situ for screen/absorbent samples of various materials and dimensions, within a broad frequency range.</p> |
