Research on a High-Gain Interferometer Direction-Finding Method

Traditional interferometer direction-finding has been widely used in various fields. Its disadvantage is that it has high requirements for the signal amplitude of a single channel. Usually, the peak value of a single-channel signal after detection is processed. If the target signal amplitude is small or submerged by noise, the direction-finding error will increase or even direction-finding will be impossible. This paper proposes to combine beamforming with interferometer direction-finding. Subarrays are formed by multiple antennas, and the center of gravity positions of multiple array elements are taken as the positions of the synthesized virtual array elements. The synthesized multiple virtual array elements form a virtual array with a new configuration. The equiphase surface of the virtual array based on the beam pointing direction is formed through coordinate transformation. Interferometer directionfinding is performed in the coordinate system formed by the equiphase surface and the beam pointing direction. The direction-finding expression of a 16 -element uniform circular array interferometer is derived, which can be extended to symmetrically distributed virtual array elements. After measuring the angle of the target deviating from the axial direction (beam pointing angle) in the equiphase surface coordinate system, the precise position of the target in the original coordinate system is obtained through inverse coordinate transformation. Simulation results verify that this method can improve the passive direction-finding sensitivity and direction-finding accuracy.