In this article particularities of implementing integrated antennas for RFID systems are discussed including the choice of antenna type along with basics for finding the optimal frequency considering the mutual coupling of reader's and tag's antennas. Testing approaches for measuring the integrated antenna's parameters and modulation-depth measurement method allow evaluating the influence of factors degrading antenna performance such as technological metallization, slotting, packaging etc. Obtained results show an efficiency of integrated antenna of up to 20% without the package, an optimal frequency range of 4 -6 GHz and the possibility to operate with signals using FSK, BPSK and amplitude modulation methods.