Synthesis of phase-only thinned concentric elliptical antenna arrays based on the topology optimization continuous 0–1 differentiation

This paper proposes a gradient-based optimization method for pattern synthesis of phase-only thinned concentric elliptical antenna arrays (CEAAs) with the tangent interpolation function of continuous 0–1 differentiation in topology optimization. The optimization model is reasonably constructed and actualized by simultaneously optimizing the presence or absence of metal materials and the excitation phase within each array element. In order to facilitate solving the optimization problem using the gradient-based algorithms and performing the CEAA pattern synthesis, the tangent interpolation function of metal material with a pseudo-resistance is introduced to realize the continuous 0–1 differentiation of each array element. The design objective is to maximize the difference between the radiation energies of the main-beam direction and the peak sidelobe level with the constraints on the total number of remaining elements. For ensuring that the mutual coupling between the elements is accurately considered, the full-wave method of moments (MoM) is integrated into the optimization method to synthesize the array radiation pattern. Typical examples are provided to verify the effectiveness of the proposed method. Compared with the uniform array and the reference CEAA, the proposed method not only achieves the sidelobe suppression and aperture reduction but also significantly decreases the total number of array elements.