Mutual coupling compensation applied to a uniform circular array

In this paper, two approaches for compensation of mutual coupling and phase shifts in a passive radar system based on a circular array are compared. The first method is based on the measurement of the antenna scattering parameters and of further relative phase and amplitude variations between the channels introduced by the receiver analog front-end and by the analog-to-digital converter. The second method derives a total coupling matrix, which contains both the antenna and the front-end contributions, by measuring the signals transmitted from known positions. The two procedures have been applied to an FM-based passive radar that uses an 8-element circular array. It appears that for the considered geometry the antenna mutual coupling does not significantly affect the radiation pattern, while the major contribution is due to phase shifts introduced by the receiver front-end.