Evaluation of the influence of directivity factor of directive elements of conformal antenna arrays on the performances of Azimuth-elevation DOA estimation

The article discusses the functioning of the radio direction-finding methods in the system of circular antenna arrays formed of the designed radiators, the directional factor of which is not equal to 1. The accuracy of determining the angular coordinates with the direction-finding method with superresolution MUSIC is estimated there. Direction-of-arrival (DOA) estimation of signal sources takes a great interest in such tasks as radars, sonar and wireless communications. DOA-estimation is crucial for radar technologies to detect and divide several signal sources, while in wireless communication systems information about signal coordinates allows spatial multiplexing to increase the number of simultaneously working users [1]. This article focuses on determining the effect of the characteristics of the antenna elements to the achievable accuracy in the evaluation of the angular coordinates of radio sources. While equidistant linear antenna arrays received most of the attention in the literature on the beamforming and direction-finding, uniform circular antenna arrays (CAR) are an attractive alternative because they are capable of producing more uniform characteristics in all viewing angles. Most of the references on adaptive antennas considering the topics on direction-of-arrival estimation and beamforming assume that either isotropic antenna elements or omnidirectional antennas are used. In this kind of antenna elements the gain is equal in all directions (for example: half-wavelength dipoles) [2-6]. Therefore, the research of the impact of such characteristics of the antenna elements as a directivity factor on the DOA-estimation performances is of great importance.