To address the issues of limited degrees-of-freedom for interference suppression and inter-element mutual coupling in a uniform linear array

this paper proposes an adaptive beam forming method for unmanned aerial vehicle (UAV) navigation based on maximum inter-element spacing constraint (MISC) coarray interpolation. This method aims to increase the number of degrees-of-freedom for interference suppression and reduce the mutual coupling effects between antenna elements. The MISC array covariance matrix is vectorized

and a difference coarray is constructed. Due to the presence of holes in the difference coarray

it is interpolated to form a virtual uniform linear array. An optimization problem based on atomic norm minimization is formulated and transformed into a convex optimization problem. By solving this problem

the signal vector of the interpolated virtual uniform linear array (IVULA) can be recovered. The IVULA signal covariance matrix has a Toeplitz structure

and by exploiting the subspace rotation-invariant property

the directions of all signals can be computed. The covariance fitting method is employed to estimate the powers of all signals. The interference plus noise covariance matrix of the MISC array is reconstructed

the steering vector of the desired signal is predicted

determining the beam forming weight vector for the UAV navigation receiver. Simulation experiments demonstrate that the proposed method is suitable for MISC arrays

outputs higher signal-plus-interference-to-noise ratios than current methods

and exhibits good robustness to model errors.