Abstract

Airborne radomes are critical for protecting the antenna from the environment. However, the presence of radomes can affect the performance of the antenna systems and therefore it is essential to consider the radome while designing the antenna system. A well-designed radome is transparent to the electromagnetic waves within the operating frequency band of the antenna while satisfying the structural and aerodynamic requirements. In this paper, a multidisciplinary design optimization workflow is proposed for designing airborne radomes. The electromagnetic performance and the mechanical response of the radome are considered simultaneously while optimizing the material properties and geometrical parameters of the radome wall structure. Aerodynamic forces on the radome surface are extracted from a steady-state Reynolds-Averaged Navier-Stokes computational fluid dynamics analysis and mapped onto the structural simulation in a one-way coupling. The structural integrity of the radome is simulated by applying the aerodynamic pressure from the CFD analysis as a static load in a linear static analysis as well as a buckling analysis. Additionally, an explicit bird strike analysis is performed using the smoothed particle hydrodynamics (SPH) method in order to prevent structure failure in an event of a bird strike. A hybrid simulation approach is utilized in order to model the electromagnetic interaction between the antenna system and the radome based on a 3D full-wave analysis technique as well as Physical Optics. To validate the design approach a multi-layered sandwich radome protecting a weather radar antenna operating at X-band (9.3 GHz) is studied. The antenna and the radome are situated at the nose of a regional jet type commercial aircraft. A slotted waveguide antenna array is used to achieve the scanning behaviour. The aerodynamic forces on the radome surface were computed at typical cruise flight conditions to provide the input for calculating the resulting stress under the aerodynamic loading. The thickness and the stacking sequences of the different layers of the radome are optimized with the objective to maximize the transmission coefficient subjected to the constraining buckling safety factor. Additionally, the maximum structural damage in the event of a high velocity bird impact is simulated to ensure that no loss of structural integrity of the radome occurs with the optimal design parameters. The lighting protection strips on the radome have also been included in the study to investigate the impact of the solid and segmented strips on the radiation performance of the antenna. The model based engineering approach offers an efficient workflow to automate the multiphysics analysis of the radome resulting in optimal designs for electromagnetic and mechanical performance of radomes. This approach enables early stage design validation of radomes and accurate prediction of antenna behaviour with the radome, thus reducing the amount for physical prototyping and therefore design costs.