Methods for determining the phase difference of the output signals for the receiving elements of a phased antenna array in a radiophoton circuit with parallel and series pairwise connection of electro-optical modulators

Obtaining accurate phase values of the output signals for the receiving elements of a phased array antenna is one of the crucial issues relating to radio-photon technologies in radar and radio communication. The paper considers measuring the phase difference of the output signals for the receiving elements of a phased array antenna using electro-optical Mach–Zehnder modulators as part of a radio-photonic device. The dependences of the output signals of the optical signal receivers and the phase difference of the output signals for the receiving elements of the phased antenna array in the radio-photonic scheme are formalized for different variants of the connection of electro-optical Mach–Zehnder modulators. The authors propose the methods for determining the phase difference of the output signals for the receiving elements of a phased array antenna based on parallel and series connection of electro-optical Mach–Zehnder modulators into radio-photonic devices. A comparative assessment of the proposed methods is carried out. It is shown that the method based on the determination of the phase difference with the parallel connection of electro-optical modulators produces 1.58 times less error than the method with the series connection. The description of the radio-photonic scheme of the phase direction finder is presented. The proposed scheme provides high accuracy in measuring the phase difference of the output signals for individual receiving elements of a phased array antenna. The results of the work can be applied by specialists in the field of advanced radar and radio communication systems.