Separarea efectului curenților de mod comun de pe cablurile de alimentare ale antenelor din câmpul total radiat / Discrimination of common mode currents effect on antenna feeders from the total radiated field

In order to obtain accurate measurements on antenna radiation, it is very important to study the contribution of the feeder to the total radiated field. In this thesis, we proposed to apply a set of methods in order to discriminate the radiation generated by the common mode currents flowing on the surface of the feed cable, from the antenna radiation. Methods for assessment and reduction of the common mode currents on antenna feeders, are also developed in this work. Regarding the principle underlying such a discrimination, two directions are approached: one that exploits a possible orthogonal polarization of the two sources, and another that allows the discrimination of the two effects due to the variability of the common mode currents with the distance. The studies covered both the situation in which the common mode currents occur when feeding a symmetric antenna through an asymmetric line, and also when feeding a monopole antenna on a small ground plane. We also proposed two different approaches for our method, depending on the number of the symmetry degree of the antenna under test.